Attorney Docket No.9833.6700.WO BASE STATION ANTENNAS HAVING AT LEAST ONE GRID REFLECTOR AND RELATED DEVICES RELATED APPLICATIONS [0001] This patent application claims the benefit of and priority to U.S. Provisional Application Serial Number 63/377,636, filed September 29, 2022, the contents of which are hereby incorporated by reference as if recited in full herein. BACKGROUND [0001] The present invention generally relates to radio communications and, more particularly, to base station antennas for cellular communications systems. [0002] Cellular communications systems are well known in the art. In a cellular communications system, a geographic area is divided into a series of regions that are referred to as "cells" which are served by respective base stations. The base station may include one or more antennas that are configured to provide two-way radio frequency ("RF") communications with mobile subscribers that are within the cell served by the base station. In many cases, each cell is divided into "sectors." In one common configuration, a hexagonally shaped cell is divided into three 120º sectors in the azimuth plane, and each sector is served by one or more base station antennas that have an azimuth Half Power Beamwidth (HPBW) of approximately 65°. Typically, the base station antennas are mounted on a tower or other raised structure, with the radiation patterns (also referred to herein as "antenna beams") that are generated by the base station antennas directed outwardly. Base station antennas are often implemented as linear or planar phased arrays of radiating elements. [0003] In order to accommodate the increasing volume of cellular communications, cellular operators have added cellular service in a variety of new frequency bands. In order to increase capacity without further increasing the number of base station antennas, multi-band base station antennas have been introduced which include multiple linear arrays of radiating elements. Additionally, base station antennas are now being deployed that include "beamforming" arrays of radiating elements that include multiple columns of radiating elements. The radios for these beamforming arrays may be integrated into the antenna so that the antenna may perform active beamforming (i.e., the shapes of the antenna beams generated by the antenna may be adaptively changed to improve the performance of the antenna). These beamforming arrays typically operate in higher frequency bands, such as various portions of the 3.3-5.8 GHz frequency band. Antennas having integrated radios that can adjust the Attorney Docket No.9833.6700.WO amplitude and/or phase of the sub-components of an RF signal that are transmitted through individual radiating elements or small groups thereof are referred to as "active antennas." Active antennas can generate narrowed beamwidth, high gain, antenna beams and can steer the generated antenna beams in different directions by changing the amplitudes and/or phases of the sub-components of RF signals that are transmitted through the antenna. [0004] With the development of wireless communication technology, an integrated base station antenna including a passive module and an active antenna module with an active antenna has emerged. The passive module may include one or more passive arrays of radiating elements that are configured to generate relatively static antenna beams, such as antenna beams that are configured to cover a 120 degree sector (in the azimuth plane) of a base station antenna. The passive arrays may comprise arrays that operate under second generation (2G), third generation (3G) or fourth generation (4G) cellular standards. These passive arrays are not configured to perform active beamforming operations, although they typically have remote electronic tilt (RET) capabilities which allows the shape of the antenna beam to be changed via electromechanical means in order to change the coverage area of the antenna beam. The active antenna module may include one or more arrays of radiating elements that operate under fifth generation (or later) cellular standards. These arrays typically have individual amplitude and phase control over subsets of the radiating elements therein and perform active beamforming. [0005] FIGS.1 and 2 illustrate an example of a prior art base station antenna 10 that includes a pair of beamforming arrays and associated beamforming radios. The base station antenna 10 is typically mounted with the longitudinal axis L of the antenna 10 extending along a vertical axis (e.g., the longitudinal axis L may be generally perpendicular to a plane defined by the horizon) when the antenna 10 is mounted for normal operation. The front surface of the antenna 10 is mounted opposite the tower or other mounting structure, pointing toward the coverage area for the antenna 10. The antenna 10 includes a radome 11 and a top end cap 20. The antenna 10 also includes a bottom end cap 30 which includes a plurality of connectors 40 mounted therein. As shown, the radome 11, top cap 20 and bottom cap 30 define an external housing 10h for the antenna 10. An antenna assembly is contained within the housing 10h. [0006] FIG.2 illustrates that the antenna 10 can include one or more radios 50 that are mounted to the housing 10h. As the radios 50 may generate significant amounts of heat, it may be appropriate to vent heat from the active antenna in order to prevent the radios 50 from overheating. Accordingly, each radio 50 can include a (die cast) heat sink 54 that is shown mounted on the rear surface of the radio 50. The heat sinks 54 are thermally conductive and include a plurality of fins 54f. Heat generated in the radios 50 passes to the heat sink 54 and Attorney Docket No.9833.6700.WO spreads to the fins 54f. As shown in FIG.2, the fins 54f are external to the antenna housing 10h. This allows the heat to pass from the fins 54f to the external environment. Further details of example conventional base station antennas can be found in co-pending WO2019/236203 and WO2020/072880, the contents of which are hereby incorporated by reference as if recited in full herein. SUMMARY [0007] Embodiments of the present invention are directed to base station antennas with at least one grid reflector configured to allow high band radiating elements to propagate electromagnetic waves therethrough and to reflect lower band signal from lower band radiating elements in front of the at least one grid reflector. The at least one grid reflector can have right and left sides that extend in a longitudinal direction and that project forward at an oblique angle relative to a primary, medially extending portion of the at least one grid reflector between the right and left sides. [0008] The at least one least one grid reflector with a respective array of unit cells. [0009] The unit cells can be defined by conductive patches. [00010] The unit cells can be defined by a pattern in sheet metal. [00011] Embodiments of the present invention are directed to a base station antenna that includes a first grid reflector defining a first frequency selective surface (FSS), a second grid reflector defining a second FSS residing behind the first grid reflector, and an active antenna residing behind the first and second grid reflectors. [00012] The first grid reflector can have a first primary surface and the second grid reflector can have a second primary surface. The first and second primary surfaces can be parallel to each other. [00013] The base station antenna can further include a first plurality of radiating elements residing in front of the first grid reflector and a second plurality of radiating elements residing behind the first gird reflector and behind the second grid reflector and each can have an array of unit cells, with array of unit cells of the first grid reflector provided in a different pattern than the array of unit cells of the second grid reflector. [00014] The first plurality of radiating elements can operate in a first frequency band and the second plurality of radiating elements can operate in a second frequency band. [00015] The first plurality of radiating elements can include low band radiating elements that are configured to operate in a first frequency band, and the second plurality of radiating elements can include higher band radiating elements that are configured to operate in a second Attorney Docket No.9833.6700.WO frequency band. The second frequency band can encompass higher frequencies than the first frequency band. [00016] The at least one grid reflector can be defined by a pattern of unit cells in sheet metal. [00017] The at least one grid reflector can include a pattern of unit cells provided by conductive patches in or on a dielectric substrate or provided as metallized pattern on a plastic or fiberglass substrate. [00018] The at least one grid reflector can be configured to allow RF energy in at least part of a 3.1-4.2 GHz frequency band to propagate therethrough. [00019] The at least one grid reflector can be configured to allow high-frequency electromagnetic waves within the range of 2300 MHz to 4000 MHz to pass through. [00020] Embodiments of the invention are directed toa base station antenna that includes a grid reflector having opposing right and left sides and a medial segment residing between the right and left sides. The right and left sides project forwardly at an oblique angle relative to the medial segment. [00021] The grid reflector can be provided as a first grid reflector and the base station antenna can further include a second grid reflector behind the first grid reflector. [00022] The second grid reflector can have opposing right and left sides and a medial segment residing between the right and left sides and the right and left sides can project forwardly at an oblique angle relative to the medial segment. [00023] The oblique angle of the right and left sides of the second grid reflector can be the same as the oblique angle of the right and left sides of the first grid reflector. [00024] At least the medial segments of the first and second grid reflectors can be parallel to each other and reside in front an active antenna unit. [00025] The first grid reflector can have a first array of unit cells and the second grid reflector can have a second array of unit cells that is arranged in a different pattern from the first array of unit cells. [00026] A center aperture of at least some aligned unit cells of the first and second grid reflectors can be aligned to define a continuous forward through space therebetween and toward a front radome of the base station antenna. [00027] The first array of unit cells can define a band pass filter for radiating elements residing behind the first and second grid reflectors. Attorney Docket No.9833.6700.WO [00028] The second array of unit cells define a band stop filter for radiating elements residing in front of the first grid reflector and also define a band pass filter for radiating elements residing in back of the second grid reflector. [00029] The first and second grid reflectors can be spaced apart from radiating elements behind the first and second grid reflectors a distance of one quarter of a wavelength of a center operating frequency of the radiating elements residing behind the first and second grid reflectors. [00030] The base station antenna can further include a first plurality of radiating elements residing in front of the first grid reflector and a second plurality of radiating elements residing behind the first grid reflector. [00031] The first plurality of radiating elements can operate in a first frequency band and the second plurality of radiating elements can operate in a second frequency band. The base station antenna can further include right and left side rails that extend in a longitudinal direction. The first grid reflector can be coupled to the right and left side rails and define a chamber therebetween and behind the first grid reflector. The second grid reflector can reside inside the chamber. [00032] The first plurality of radiating elements can be/include low band radiating elements that are configured to operate in a first frequency band. The second plurality of radiating elements can be/include higher band radiating elements that are configured to operate in a second frequency band, the second frequency band encompassing higher frequencies than the first frequency band. [00033] At least one of the first grid reflector and/or the second grid reflector can have an array of unit cells in sheet metal. [00034] At least one of the first grid reflector and/or the second grid reflector can have an array of unit cells provided by conductive patches in or on a dielectric substrate. [00035] At least one of the first grid reflector and/or the second grid reflector can have an array of unit cells provided by conductive patches on a non-conductive polymer and/or plastic substrate. [00036] The first grid reflector and the second grid reflector can be configured to allow RF energy in a defined frequency band to propagate therethrough. [00037] The second grid reflector can be attached to a radome. [00038] The radome can be a rear radome of the base station antenna. The second grid reflector can be attached to an internal facing surface of the rear radome. Attorney Docket No.9833.6700.WO [00039] The first grid reflector can have a plurality of apertures that are larger than apertures of unit cells of an array of unit cells defining a frequency selective surface. The plurality of larger apertures are aligned with feed stalks of respective radiating elements. The second grid reflector can have an array of unit cells defining a frequency selective surface but can be devoid of the plurality of larger apertures provided in the first grid reflector. [00040] The base station antenna can include a plurality of laterally extending struts that can be coupled to the first grid reflector and that are longitudinally spaced apart. [00041] The right and left sides and the medial segment can all include unit cells of an array of unit cells defining a frequency selective surface. [00042] The base station antenna can also include at least one matching layer in front of the grid reflector. [00043] The first and second grid reflectors can each have an array of unit cells. The array of unit cells of one or both of the first and second grid reflectors can be configured to absorb, block and/or reflect at least one of RF energy in a first frequency band and/or RF energy in a second frequency band, and pass RF energy in a third frequency band where the third frequency band encompasses frequencies between the first and second frequency bands. [00044] Yet other embodiments of the present invention are directed to a base station antenna that includes a front radome and first and second grid reflectors spaced apart in a front to back direction and each of the first and second grid reflectors having right and left sides that project forward at an oblique angle in a Z-dimension and that are positioned behind the front radome. [00045] The right and left sides of the first and second grid reflectors can define side walls and each of the side walls comprises unit cells of an array of unit cells. [00046] The right side and left sides reside on opposing sides of a laterally and longitudinally extending forward facing surface. [00047] The base station antenna can further include a first plurality of radiating elements residing behind the first and second grid reflectors, and a second plurality of radiating elements residing in front of the grid reflector. [00048] The first plurality of radiating elements can operate in a first frequency band and the second plurality of radiating elements operate in a second frequency band. [00049] The first plurality of radiating elements can have high band radiating elements that operate in at least part of a 3.1-4.2 GHz frequency band. The second plurality of radiating elements can have radiating elements that operate in at least part of a lower frequency band than the high band radiating elements. Attorney Docket No.9833.6700.WO [00050] The first and second grid reflectors can each have a respective pattern of unit cells in sheet metal. [00051] The first and second grid reflectors can have a respective pattern of unit cells provided by conductive patches in or on a dielectric substrate. [00052] The first and second grid reflectors can have a respective pattern of unit cells provided by conductive patches in or on a plastic and/or polymer substrate. [00053] The first and second grid reflectors can be configured to allow RF energy in at least part of a 3.1-4.2 GHz frequency band to propagate therethrough. [00054] The base station antenna can further include at least one matching layer positioned in front of the first grid reflector. [00055] The second plurality of radiating elements can be provided in an active antenna module. [00056] The first grid reflector can have a plurality of large apertures that are larger than unit cell apertures provided by unit cells of the array of unit cells. The large apertures can be aligned with feed stalks of respective radiating elements. [00057] The second grid reflector can have an array of unit cells with apertures but can be devoid of the large apertures aligned with the feed stalks arranged in the first grid reflector. [00058] The base station antenna can further include a primary reflector coupled to the first grid reflector. A plurality of laterally extending struts that can be coupled to the first grid reflector and can be longitudinally spaced apart. [00059] The first and second grid reflectors can each have an array of unit cells. Each unit cell can be defined by a metal perimeter surrounding a shaped aperture or apertures. The unit cell of the second grid reflector can have aperture(s) defining a greater surface area of a respective unit cell relative to the aperture(s) of a respective unit cell of the first grid reflector. [00060] A center aperture of at least some aligned unit cells of the first and second grid reflectors can be aligned to define a continuous forward through space therebetween and toward a front radome of the base station antenna. [00061] The base station antenna can further include at least one feed board with one or more cutouts that align with the forward through space of some of the unit cells. [00062] The base station antenna can also include: low band radiating elements projecting forward of the grid reflector; mid-band radiating elements projecting forward of the first grid reflector; a second grid behind the grid reflector configured as a band stop filter to block signal from the mid-band radiating elements; and a third grid behind the second grid configured as a band stop filter to block signal from the mid-band radiating elements. Attorney Docket No.9833.6700.WO [00063] The base station antenna can include feed networks for some radiating elements on a front primary surface of the grid reflector and feed networks for other radiating elements on a rear primary surface of the grid reflector. [00064] The feed networks on the front primary surface can include first feed networks arranged in horizontal and longitudinal linear segments arranged on the front primary surface of the grid reflector, and the feed networks on the rear primary surface can include second feed networks arranged in horizontal and linear segments arranged on the rear primary surface of the grid reflector. [00065] The first feed networks can couple to feed stalks of low band radiating elements. [00066] The second feed networks can couple to feed stalks of mid-band radiating elements that extend through apertures in the grid reflector. [00067] Other aspects are directed to a base station antenna that includes: a first grid layer defining a band pass filter configured to pass RF signal in a high frequency band from high band radiating elements behind the first grid reflector; a second grid layer behind the first grid layer configured as a band stop filter to block signal from mid-band radiating elements; and a third grid layer behind the second grid layer configured as a band stop filter to block signal from the mid-band radiating elements. [00068] The base station antenna can also include feed networks for some radiating elements on a front primary surface of the first grid layer and feed networks for other radiating elements on a rear primary surface of the first grid layer. [00069] The feed networks on the front primary surface can include first feed networks arranged in horizontal and longitudinal linear segments arranged on the front primary surface of the grid reflector and the feed networks on the rear primary surface can include second feed networks arranged in horizontal and linear segments arranged on the rear primary surface of the first grid layer. [00070] The first feed networks can couple to feed stalks of low band radiating elements. [00071] The second feed networks can couple to feed stalks of mid-band radiating elements that can extend through apertures in the grid reflector. [00072] The second grid layer can provide the band stop filter with a band stop frequency band in a range of 1.7-2.7 GHz and can have a first frequency at maximum rejection in a lower half of the band stop frequency band and the third grid layer can provide the band stop filter with a band stop frequency band in a range of 1.7-2.7 GHz and can have a second frequency at maximum rejection in a higher half of the band stop frequency band. Attorney Docket No.9833.6700.WO [00073] The second grid layer can provide the band stop filter with a band stop frequency band in a range of 1.7-2.7 GHz and the third grid layer can provides the band stop filter with a band stop frequency band in a range of 1.7-2.7 GHz and a frequency at maximum rejection for the band stop filters of the second and third grid layers are within 2 GHz to 2.25 GHz. [00074] Yet other aspects are directed to a base station antenna that includes: a grid reflector; a plurality of spaced apart feed networks on a front primary surface of the grid reflector; and a plurality of spaced apart feed networks on a rear primary surface of the first grid reflector. [00075] The feed networks on the front primary surface can include first feed networks arranged in horizontal and longitudinal linear segments on or in front of the front primary surface of the grid reflector and the feed networks on the rear primary surface can include second feed networks arranged in horizontal and linear segments on or behind the rear primary surface of the grid reflector. [00076] The first feed networks can couple to feed stalks of low band radiating elements. [00077] The second feed networks can couple to feed stalks of mid-band radiating elements that extend through apertures in the grid reflector. [00078] Additional aspects are directed to a base station antenna that includes: a first grid layer; a second grid layer behind the first grid layer; and a third grid layer behind the second grid layer. The first grid layer extends laterally and longitudinally a greater distance in than at least one of the second and third grid layers. [00079] The first grid layer, the second layer and the third grid layer can all reside (only) at a top to middle portion of the base station antenna (above the middle portion in a longitudinal direction). [00080] The first grid layer can be sheet metal with an array of unit cells and merges at a bottom portion into a primary reflector. [00081] The base station antenna can include a plurality of mid-band radiating elements residing in front of the first grid layer, aligned with the second grid layer and the third grid layer. [00082] The second and third grid layers can reside behind the first grid layer only across a lower portion (lower 20%-50%) of the first grid layer, behind mid-band radiating elements. [00083] The second and third grid layers can be provided as respective laterally spaced apart segments positioned at left and right segments of the base station antenna, behind the first grid reflector. Attorney Docket No.9833.6700.WO [00084] Yet other aspects of the present invention are directed to a base station antenna that includes a first grid reflector having a first array of unit cells and a second grid layer having a second array of unit cells and positioned behind the first grid reflector. The second array of unit cells has a different configuration than the first array of unit cells. The base station antenna also includes a plurality of linear arrays of radiating elements in front of the first array of unit cells. The first and second array of unit cells are configured to allow RF energy from radiating elements residing behind the second grid layer to propagate therethrough. The second array of unit cells is configured to block, reflect or absorb RF energy generated by the linear arrays of radiating elements in front of the first grid reflector. [00085] It should be noted that various aspects of the present disclosure described for one embodiment may be included in other different embodiments, even though specific description is not made for the other different embodiments. In other words, all the embodiments and/or features of any embodiment may be combined in any manner and/or combination, as long as they are not contradictory to each other. BRIEF DESCRIPTION OF THE DRAWINGS [00086] FIG.1 is a perspective view of a prior art base station antenna. [00087] FIG.2 is a back view of another prior art base station antenna. [00088] FIG.3A is a back perspective view of an example base station antenna coupled to an active antenna module according to embodiments of the present invention. [00089] FIG. 3B is a side, back perspective view of another example base station antenna coupled to an active antenna module according to embodiments of the present invention. [00090] FIG. 4 is a perspective view of an example primary reflector that can be provided in a base station antenna, such as the base station antenna shown in FIG.3A or FIG. 3B, according to embodiments of the present invention. [00091] FIG.5A is a front perspective view of a grid reflector for a base station antenna according to embodiments of the present invention. [00092] FIG.5B is a front view of the grid reflector shown in FIG.5A. [00093] FIG.6A is a front view of a section of a grid reflector according to embodiments of the present invention. [00094] FIG.6B is an enlarged front view of a unit cell of the grid reflector shown in FIG.6A. Attorney Docket No.9833.6700.WO [00095] FIG.7A is a front view of a section of another embodiment of a grid reflector according to embodiments of the present invention. [00096] FIG.7B is an enlarged front view of a unit cell of the grid reflector shown in FIG.7A. [00097] FIG.8A is a front view of a section of another embodiment of a grid reflector according to embodiments of the present invention. [00098] FIG.8B is an enlarged front view of a unit cell of the grid reflector shown in FIG.8A. [00099] FIG.9A is a front view of a section of another embodiment of a grid reflector of according to embodiments of the present invention. [000100] FIG.9B is an enlarged front view of a unit cell of the grid reflector shown in FIG.9A. [000101] FIG.10 is a front view of another embodiment of a grid reflector according to embodiments of the present invention. [000102] FIG.11 is a front view of another embodiment of a grid reflector according to embodiments of the present invention. [000103] FIG.12A is a front view of another embodiment of a grid reflector for a base station antenna according to embodiments of the present invention. [000104] FIG. 12B is a greatly enlarged front view of a unit cell of the grid reflector shown in FIG.12A. [000105] FIG.13A is a front view of an example grid reflector for a base station antenna according to embodiments of the present invention. [000106] FIG. 13B is a greatly enlarged front view of a unit cell of the grid reflector shown in FIG.13A. [000107] FIG.14A is a front view of an example grid reflector for a base station antenna according to embodiments of the present invention. [000108] FIG. 14B is a greatly enlarged front view of a unit cell of the grid reflector shown in FIG.14A. [000109] FIG.15A is a front view of an example grid reflector for a base station antenna according to embodiments of the present invention. [000110] FIG. 15B is a greatly enlarged front view of a unit cell of the grid reflector shown in FIG.15A. [000111] FIG.16A is a front view of an example grid reflector for a base station antenna according to embodiments of the present invention. Attorney Docket No.9833.6700.WO [000112] FIG. 16B is a greatly enlarged front view of a unit cell of the grid reflector shown in FIG.16A. [000113] FIG.17A is a front view of an example grid reflector for a base station antenna according to embodiments of the present invention. [000114] FIG. 17B is a greatly enlarged front view of a unit cell of the grid reflector shown in FIG.17A. [000115] FIG.18A is a front view of an example grid reflector for a base station antenna according to embodiments of the present invention. [000116] FIG. 18B is a greatly enlarged front view of a unit cell of the grid reflector shown in FIG.18A. [000117] FIGS.19A-19D are front views of additional embodiments of the grid reflector according to embodiments of the present invention. [000118] FIGS.20-22 are front views of yet additional embodiments of the grid reflector according to embodiments of the present invention. [000119] FIG.23A is a front, side perspective view of an antenna assembly and example grid reflector of a base station antenna according to embodiments of the present invention. [000120] FIG. 23B is an enlarged front, side perspective view of a top portion of the antenna assembly and grid reflector shown in FIG.23A. [000121] FIG.23C is a front schematic view of a reflector comprising first and second grid reflectors and a primary reflector according to embodiments of the present invention. [000122] FIG.24 is a front, side perspective view of a base station antenna with the front and rear radome omitted to illustrate placement of a mMIMO antenna array behind the grid reflector according to embodiments of the present invention. [000123] FIG. 25 is a partially exploded view of an example active antenna module according to embodiments of the present invention. [000124] FIGS.26A and 26B are simplified lateral section views of example base station antennas and cooperating active antenna modules according to embodiments of the present invention. [000125] FIG. 27 is an enlarged simplified, sectional view of an example base station antenna and cooperating active antenna module according to embodiments of the present invention. [000126] FIG.28A is a front view of a portion of a base station antenna, shown without the front radome, illustrating an example grid reflector (e.g., FSS) according to embodiments of the present invention. Attorney Docket No.9833.6700.WO [000127] FIG.28B is a rear view of the portion of the base station antenna shown in FIG. 28A, shown without the back radome according to embodiments of the present invention. [000128] FIG.28C is a simplified schematic lateral section view of a top portion of the base station antenna shown in FIGS. 28A, 28B, illustrating an example position of the FSS relative to the rear radome according to embodiments of the present invention. [000129] FIG.28D is a simplified schematic lateral section view of a top portion of the base station antenna shown in FIGS. 28A, 28B illustrating an alternate position of the FSS relative to the embodiment shown in FIG. 28C, according to embodiments of the present invention. [000130] FIG.28E is a rear view of base station antenna without a rear radome, showing the FSS and matching layers according to embodiments of the present invention. [000131] FIG.28F is a front perspective view of the base station antenna shown in FIG. 28E, shown without the front radome, according to embodiments of the present invention. [000132] FIG.28G is a simplified lateral section view of the base station antenna shown in FIGS.28E/28F according to embodiments of the present invention. [000133] FIG.29A is a front view of a portion of a base station antenna, shown without the front radome, illustrating another example FSS according to embodiments of the present invention. [000134] FIG.29B is a rear view of the portion of the base station antenna shown in FIG. 29A, shown without the back radome according to embodiments of the present invention. [000135] FIG.29C is a rear view of the portion of a base station antenna similar to that shown in FIG.29A, shown without the back radome according to embodiments of the present invention. [000136] FIG.29D is a front, perspective view of the base station antenna shown in FIG. 29C, shown without the front radome and without the side radomes, according to embodiments of the present invention. [000137] FIG.29E is a simplified lateral section view of the base station antenna shown in FIGS.29C/29D according to embodiments of the present invention. [000138] FIG.30 is a front, side perspective view of a portion of a base station antenna (shown without the radome) according to embodiments of the present invention. [000139] FIG.31 is a front, side perspective view of a portion of a base station antenna (shown without the radome) according to other embodiments of the present invention. [000140] FIG. 32 is a front view of a portion of a base station antenna (shown without the radome) according to yet other embodiments of the present invention. Attorney Docket No.9833.6700.WO [000141] FIG.33 is a rear view of the portion of the base station antenna shown in FIG. 32 according to embodiments of the present invention. [000142] FIG. 34 is a side, front perspective view of an example three-dimensional reflector configured for a base station antenna according to embodiments of the present invention. [000143] FIG.35 is an end view of the reflector shown in FIG.34. [000144] FIG. 36 is a simplified lateral sectional view of a base station antenna with a plurality of reflectors stacked in a front to back direction according to embodiments of the present invention. [000145] FIG. 37 is a simplified lateral sectional view of a base station antenna with a plurality of reflectors stacked in a front to back direction and with matching layers according to embodiments of the present invention. [000146] FIG. 38A is a front, side perspective view of another example reflector for a base station antenna according to embodiments of the present invention. [000147] FIG. 38B is a simplified end view of the reflector shown in FIG. 38A illustrating cooperating radiating elements according to embodiments of the present invention. [000148] FIG.39A is a front, side perspective view of a portion of a base station antenna, shown without the front radome, illustrating another example FSS configuration according to embodiments of the present invention. [000149] FIG.39B is a rear view of the portion of the base station antenna shown in FIG. 39A, shown without the back radome according to embodiments of the present invention. [000150] FIG.39C is a simplified lateral section view of the base station antenna shown in FIGS.39A/39B according to embodiments of the present invention. [000151] FIG.40 is a simplified lateral section view of a base station antenna illustrating a matching layer, adjacent the rear radome and in back of a reflector such as a FSS and/or grid reflector, according to embodiments of the present invention. [000152] FIGS.41A-41G are front, side, partially transparent views of portions of a base station antenna showing examples of stacked reflector configurations according to embodiments of the present invention. [000153] FIG.42 is a partially transparent simplified lateral section view of a portion of a base station antenna according to embodiments of the present invention. [000154] FIG. 43A is an enlarged side perspective view of the stacked grid reflectors shown in FIG.42. Attorney Docket No.9833.6700.WO [000155] FIG.43B is a top/bottom end view of the stacked grid reflectors shown in FIG. 43A. [000156] FIG. 44A is a top/bottom end view of another embodiment of a stacked grid reflector arrangement comprising more than two stacked grid reflectors according to embodiments of the present invention. [000157] FIG.44B is a side perspective view of the embodiment shown in FIG.44A. [000158] FIGS. 44C, 44D and 44E are schematic illustrations of a side portion of the first and second grid reflectors illustrating example configurations thereof according to embodiments of the present invention. [000159] FIG. 45 is a side perspective view of a portion of stacked grid reflectors according to embodiments of the present invention. [000160] FIG.46 is a front view of the portion of the first grid reflector shown in FIG. 45 and illustrating an example pattern of a respective array of unit cells configured to define a band pass or band stop filter according to embodiments of the present invention. [000161] FIG.47 is a front view of a portion of the second grid reflector shown in FIG. 45 and illustrating a respective example pattern of an array of unit cells configured to define a band stop or band pass filter using a different pattern from the first grid reflector according to embodiments of the present invention. [000162] FIG.48A is a partially transparent simplified lateral section view of a portion of a base station antenna according to embodiments of the present invention. [000163] FIG.48B is a simplified section view of another embodiment of a base station antenna according to embodiments of the present invention. [000164] FIG.49 is a side perspective view of an example base station antenna, shown without the radome, with a cooperating active antenna module according to embodiments of the present invention. [000165] FIG. 50 is a front view of a portion of a base station antenna, shown without the radome, according to embodiments of the present invention. [000166] FIG 51A is a side perspective view of a portion of a base station antenna (shown without the radome) with stacked grid reflectors according to embodiments of the present invention. [000167] FIG.51B is a side perspective view of a portion of a base station antenna with a first grid behind low band and mid band radiating elements and with first feed board networks for the low band radiating elements provided on a front surface of the first grid according to embodiments of the present invention. Attorney Docket No.9833.6700.WO [000168] FIG.51C is a rear view of the first grid shown in FIG.51B with second feed board networks for the mid-band radiating elements on a rear surface of the first grid according to embodiments of the present invention. [000169] FIG.52 is a front, side perspective view of the feed board shown in FIG.51A. [000170] FIG. 53 is a rear view of a portion of the reflector shown in FIG. 52 that is behind a portion of the feed board shown in FIG.52. [000171] FIG.54A is a simplified, cross-sectional schematic of a portion of a base station antenna according to embodiments of the present invention. [000172] FIG.54B is an end view thereof. [000173] FIG.55A is a simplified, cross-sectional schematic of a portion of a base station antenna according to additional embodiments of the present invention. [000174] FIG.55B is an end view thereof. [000175] FIG. 56 is a simplified schematic of a portion of a base station antenna with longitudinally extending rails according to embodiments of the present invention. [000176] FIG.57 is a front view of an example of a rail system for a base station antenna according to embodiments of the present invention. [000177] FIGS. 58 and 59 are schematic illustrations of a base station antenna having multiple (partial) grid layers at selected sub-segments of the base station antenna behind the first grid reflector according to embodiments of the present invention. DETAILED DESCRIPTION [000178] FIG.3A illustrates a base station antenna 100 according to certain embodiments of the present invention. In the description that follows, the base station antenna 100 will be described using terms that assume that the base station antenna 100 is mounted for use on a tower, pole or other mounting structure with the longitudinal axis L of the base station antenna 100 extending along a vertical axis and the front of the base station antenna 100 mounted opposite the tower, pole or other mounting structure pointing toward the target coverage area for the base station antenna 100 and the rear 100r of the base station antenna 100 facing the tower or other mounting structure. It will be appreciated that the base station antenna 100 may not always be mounted so that the longitudinal axis L thereof extends along a vertical axis. For example, the base station antenna 100 may be tilted slightly (e.g., less than 10º) with respect to the vertical axis so that the resultant antenna beams formed by the base station antenna 100 each have a small mechanical downtilt. Attorney Docket No.9833.6700.WO [000179] The base station antenna 100 can couple to or include at least one active antenna module 110. The term “active antenna module” is used interchangeably with “active antenna unit” and “AAU” and “active antenna” and refers to a cellular communications unit comprising radio circuitry and associated radiating elements. The radio circuitry is capable of electronically adjusting the amplitude and/or phase of the subcomponents of an RF signal that are output to different radiating elements of an array or groups thereof. The active antenna module 110 comprises the radio circuitry and the radiating elements (e.g., a multi-input-multi- output (mMIMO) beamforming antenna array) and may include other components such as filters, a calibration network, an antenna interface signal group (AISG) controller and the like. The active antenna module 110 can be provided as a single integrated unit or provided as a plurality of stackable units, including, for example, first and second sub-units such as a radio sub-unit (box) with the radio circuitry and an antenna sub-unit (box) with a multi-column array of radiating elements and the first and second sub-units stackably attach together in a front to back direction of the base station antenna 100, with the radiating elements 1195 of an antenna assembly 1190 (FIGS. 25, 26A, 26B) closer to the front radome 111f of the housing 100h/radome 111 of the base station antenna 100 than the radio circuitry unit 1120. In some embodiments, the radiating elements 1195 may comprise a separate sub-unit from the radio circuitry and the radiating element sub-unit may be mounted within the base station antenna 100 instead of being external to the base station antenna 100. [000180] As will be discussed further below, the base station antenna 100 includes an antenna assembly 190, which can be referred to as a “passive antenna assembly”. The term “passive antenna assembly” refers to an antenna assembly having arrays of radiating elements that are coupled to radios that are external to the antenna, typically remote radio heads that are mounted in close proximity to the base station antenna 100. The arrays of radiating elements included in the passive antenna assembly 190 (FIGS. 23A, 24) are configured to form static antenna beams (e.g., antenna beams that are each configured to cover a sector of a base station). The passive antenna assembly 190 can comprise a reflector 170, 214 with radiating elements projecting in front of the reflector and the radiating elements can include one or more linear arrays of low band radiating elements that operate in all or part of the 617-960 MHz frequency band and/or one or more linear arrays of mid-band radiating elements that operate in all or part of the 1427-2690 MHz frequency band. The passive antenna assembly 190 is mounted in the housing 100h of base station antenna 100 and one or more active antenna modules 110 can releasably (detachably) couple (e.g., directly or indirectly attach) to base station antenna 100. Attorney Docket No.9833.6700.WO [000181] The base station antenna 100 has a housing 100h. The housing 100h may be substantially rectangular with a flat rectangular cross-section. The housing 100h may be provided to define at least part of a radome 111 with at least the front side 111f configured as a dielectric cover that allows RF energy to pass through in certain frequency bands. The housing 100h may also be configured to that the rear 100r defines a rear side 111r radome opposite the front side radome 111f. Optionally, the housing 100h and/or the radome 111 can also comprise two (narrow) sidewalls 100s, 111s facing each other and extending rearwardly between the front side 111f and the rear side 111r. Typically, the top side 100t of the housing 100h may be sealed in a waterproof manner and may comprise an end cap 120 and the bottom 100b of the housing 100h may be sealed with a separate end cap 130. The front side 111f, the sidewalls 111s and typically at least part of the rear side 111r of the radome 111 are substantially transparent to radio frequency (RF) energy within the operating frequency bands of the base station antenna 100 and active antenna module 110. The radome 111 may be formed of, for example, fiberglass or plastic. [000182] Still referring to FIG.3A, in some embodiments, an active antenna module 110 can attach to the base station antenna 100 using a frame 112 and accessory mounting brackets 113, 114. The rear 111r of the housing 100h may be a flat surface extending along a common plane over an entire longitudinal extent thereof or along at least a portion of the longitudinal extent thereof. [000183] FIG. 3B illustrates that the rear surface 100r can comprise a recessed and/or stepped segment 102 facing the active antenna module 110. The stepped segment 102 resides closer to a front 100f of the housing than the back wall that is defined by a primary segment of the rear 100r of the housing 100h. The stepped segment 102 can have a lateral and longitudinal extent that is the same or greater than a lateral and longitudinal extent of the active antenna module 110. The rear surface 100r can also comprise a pair of spaced apart longitudinally extending rails 118 that engage an adapter mounting bracket 1118 on the active antenna module 110 to attach the active antenna module 110 to the base station antenna housing 100h. [000184] Referring again to FIG.3A, in another embodiment, the rear surface 100r can comprise a plurality of longitudinally spaced apart mounting structure brackets, shown as upper, medial, and lower brackets, 115, 116, 117, respectively, that extend rearwardly from the housing 100h. In some embodiments, the mounting structure brackets 115, 116, 117 may be configured to couple to one or more mounting structures such as, for example, a tower, pole or building (not shown). At least two of the mounting structure brackets 115, 116 can also be configured to attach to the frame 112 of the base station antenna arrangement, where used. The Attorney Docket No.9833.6700.WO frame 112 may extend over a sub-length of a longitudinal extent L of base station antenna 100, where the sub-length is shown in FIG. 3A as being at least a major portion thereof (at least 50% of a length thereof). The frame 112 can comprise a top 112t, a bottom 112b and two opposing long sides 112s that extend between the top 112t and the bottom 112b. The frame 112 can have an open center space 112c extending laterally between the sides 112s and longitudinally between the top 112t and bottom 112b. [000185] The frame 112, where used, may be configured so that a variety of different active antenna modules 110 can be mounted to the frame 112 using appropriate accessory mounting brackets 113, 114. As such, a variety of active antenna modules 110 may be interchangeably attached to the same base station antenna 100. While the frame 112 is shown by way of example, other mounting systems may be used. [000186] In some embodiments, a plurality of active antenna modules 110 may be concurrently attached to the same base station antenna 100 at different longitudinal locations using one or more frames 112. Such active antenna modules 110 may have different dimensions, for example, different lengths and/or different widths and/or different thicknesses. [000187] Turning now to FIG. 4, an example primary reflector 214 for a base station antenna 100 is shown. As shown, the primary reflector 214 has a first section 214 ₁ that extends a first longitudinal distance and that merges into a second section 214 ₂ with spaced apart right and left side segments 214s having a lateral extent d2 that is less than a lateral extent d1 of the first section 214 ₁ . An open medial region 14 can extend longitudinally and laterally about the second section 214 ₂ . The open medial region 14 can have a lateral extent d3 that is 60-95% of the lateral extent d1, in some embodiments. The first section 214 ₁ can have a longitudinal extent that is greater than the second section 214 ₂ , typically at least 20% greater, such as 30%-80% greater, in some embodiments. [000188] FIGS. 5A and 5B illustrate an example grid reflector 170 for base station antennas 100. The grid reflector 170 comprises a frequency selective surface and may interchangeably be referred to as a “frequency selective reflector”. The grid reflector 170 can extend part of or a full lateral extent of the base station antenna 100 and at least a part of a length of the base station antenna 100. [000189] In some embodiments, the grid reflector 170 can be electrically and/or mechanically coupled to the primary reflector 214. In some embodiments, the grid reflector 170 can be positioned to reside between the right and left sides 214s of the primary reflector in the open medial region 14 (FIG. 4). Attorney Docket No.9833.6700.WO [000190] The grid reflector 170 can be provided as a non-metallic substrate(s) with metal patches arranged to define an array of unit cells 171 (also interchangeably referred to as “pattern units”) or can be a metal grid and comprises an array of unit cells 171. [000191] The non-metallic substrate can be provided as a multiple-layer printed circuit board which can be rigid, semi-rigid or a flex circuit. The non-metallic substrate can be a plastic, polymer, co-polymer with a metallized surface(s) providing conductive patches. [000192] The grid reflector 170 can be provided as a sheet of metal, such as aluminum, with the grid shaped to form the array of unit cells 171 punched or laser formed through the sheet metal or otherwise formed. [000193] The grid reflector 170 provides a frequency selective surface and/or substrate that is configured to allow RF energy (electromagnetic waves) to pass through at one or more first defined frequency range and that is configured to reflect RF energy at a different second frequency band. The frequency selective surface and/or substrate may be interchangeably referred to as a “FSS” herein. The reflector 170 of the base station antenna 100, can reside behind at least some antenna elements (see radiating elements 222, FIGS.26A, 26B) and can selectively reject some frequency bands and permit other frequency bands to pass therethrough by including the frequency selective surface and/or substrate to operate as a type of “spatial filter”. See, e.g., Ben A. Munk, Frequency Selective Surfaces: Theory and Design, ISBN: 978-0-471-37047-5; DOI:10.1002/0471723770; April 2000, Copyright © 2000 John Wiley & Sons, Inc. the contents of which are hereby incorporated by reference as if recited in full herein. [000194] The frequency selective surface and/or substrate material of the grid reflector 170 can comprise one or more of a metamaterial, a suitable RF material or even air (although air may require a more complex assembly). The term “metamaterial” refers to composite electromagnetic (EM) materials. Metamaterials may comprise sub-wavelength periodic microstructures. [000195] The FSS material can be provided as one or more cooperating layers. The FSS material can include a substrate that has a dielectric constant in a range of about 2-4, such as about 3.7 and a thickness of about 5 mil and metal patterns formed on the dielectric substrate. The thickness can vary but thinner materials can provide lower loss. [000196] In some embodiments, the frequency selective substrate/surface of the grid reflector 170 can be configured to act like a High Pass Filter essentially allowing low band energy to completely reflect (the FSS can act like a sheet of metal) while allowing higher band energy, for example, about 3.5 GHz or greater, to completely pass through. Thus, the frequency selective substrate/surface is transparent or invisible to the higher band energy and a suitable Attorney Docket No.9833.6700.WO out of band rejection response from the FSS can be achieved. The FSS material may allow a reduction in filters or even eliminate filter requirements for looking back into the radio 1120 (FIGS.25, 26A). The grid reflector 170 can be configured to define a band pass filter for one or more defined frequency bands/range and/or a band stop filter for one or more defined different frequency ranges/bands. [000197] As discussed above, in some embodiments, the grid reflector 170 with the FSS may be implemented by forming the frequency selective surface on a printed circuit board, optionally a flex circuit board. In some embodiments, the grid reflector 170, for example, may be implemented as a multi-layer printed circuit board, one or more layers of which formed with a frequency selective surface configured such that electromagnetic waves within a predetermined frequency range cannot propagate through the grid reflector 170, and wherein one or more other predetermined frequency range associated with the one or more layers of the multi-layer printed circuit board is allowed to pass therethrough. [000198] Referring to FIGS. 5A and 5B, a grid (frequency selective) reflector 170 according to embodiments of the present disclosure is shown. The grid reflector 170 can be used in the base station antenna 10 shown in FIGS. 3A, 3B, for example. The grid reflector/frequency selective reflector 170 may include a main body 21 and a frequency selective section 22 provided in the main body 21. At least the main body 21 may be metallic (e.g., formed of aluminum). The frequency selective section 22 may be provided at a position of the frequency selective reflector 170 corresponding to the installation position of the active antenna module 110 of the base station antenna 100 and may be configured to allow electromagnetic waves within a predetermined frequency range (for example, high-frequency electromagnetic waves within the range of 2300 to 4200 MHz or a portion thereof) to pass. In this way, when the base station antenna 100 is assembled, the high-frequency electromagnetic waves emitted by the active antenna module 110 can pass through the frequency selective reflector 20 via the frequency selective section 22. [000199] The frequency selective section 22 may be composed of a plurality of pattern units or unit cells 171 that are periodically arranged in the transverse and longitudinal directions of the base station antenna. Each of the pattern units/unit cells 171 may have a predetermined pattern and may include a capacitor structure and an inductor structure connected in series with the capacitor structure. In addition, each of the pattern units 171 may be electrically connected to each other through the inductor structure. For example, the inductor structure in each pattern unit/unit cell 171 may be electrically connected to the inductor structure of an adjacent pattern unit. Attorney Docket No.9833.6700.WO [000200] The resonance frequency of the frequency selective section 22 may be configured by selecting or designing the pattern and size of the capacitor structure and the inductor structure of each pattern unit/unit cell 171, as well as the spacing and arrangement of a plurality of pattern units 171 such that the electromagnetic waves within a predetermined frequency range can pass through the frequency selective section 22. [000201] Referring to FIGS. 6A-11, example grid reflectors 170 are shown with embodiments of frequency selective sections and pattern units/unit cells 171 thereof according to different embodiments of the present disclosure are shown. [000202] FIG.6A shows a frequency selective section 221 with an array according to an embodiment of the present disclosure, and FIG. 6B shows a schematic view of a single unit cell 171 of the array with a pattern unit 2210 in the frequency selective section 221 shown in FIG. 6A. As shown in FIG. 6A and FIG. 6B, the pattern unit 2210 may be substantially square. The pattern unit 2210 may include a sheet structure 2211 and a plurality of linear structures 2212. The linear structures 2212 may extend outward from a concave portion 2213 of the sheet structure 2211. The sheet structure 2211 may have a substantially square shape with four concave openings 2213, with a linear structure protruding outwardly from each concave opening. The substantially square shape of the sheet structure 2211 allows the linear structures 2212 to electrically connect to the linear structures 2212 in adjacent pattern units. The sheet structure 2211 forms a capacitor structure, and the linear structure 2212 forms an inductor structure. [000203] Referring to FIG. 6A, a circuit in which a capacitor and an inductor are connected in series can be formed using the pattern unit/unit cell 171 shown in FIG.6B. The magnitude of the capacitance can be adjusted by adjusting the distance between adjacent pattern units (for example, the distance between adjacent sheet structures 2211) and the size (for example, area, side length, etc.) of the sheet structure 2211. In addition, the magnitude of the inductance can be adjusted by adjusting the size (for example, length, width, etc.) of the linear structure 2212. The resonance frequency of the frequency selective section 22 may be adjusted by adjusting various parameters of the pattern unit 2210 so as to allow electromagnetic waves within a predetermined frequency range to pass. In the example shown in FIG.6B, by increasing the "depth" of the concave portions 2213 the length of each linear structure 2212 may be increased, thereby increasing the inductance value of the pattern unit 2210. In addition, the concave portion 2213 and the gaps among the pattern units spaced apart from each other may run through the entire frequency selective section 22. Attorney Docket No.9833.6700.WO [000204] FIG.7A is a front view of a grid reflector 170 with a frequency selective section 222 according to another embodiment of the present disclosure. FIG.7B is a schematic front view of a single unit cell 171 showing pattern unit 2220 in the frequency selective section 222 shown in FIG. 7A. As shown in FIG. 7A and FIG. 7B, the pattern unit 2220 may be rectangular or substantially square, e.g., bounded by four sides of equal or about equal lengths. For the “substantially” square configuration, the lengths can vary in a range of about +/- 20% from one another. The pattern unit 2220 may include a sheet structure 2221 and a plurality of linear structures 2222. The linear structures 2222 may extend outwardly from respective concave portions 2223 of the sheet structure 2221. The sheet structure 2221 has a substantially square shape. The linear structures 222 are electrically connected to respective linear structures 2222 in an adjacent pattern unit 2220. The sheet structure 2221 forms a capacitor structure, and the linear structures 2222 form respective inductor structures. The concave portions 2223 are located at corners of the square. As such, the linear structures 2222 extend long the diagonal direction of the square, which is beneficial to increase the length of each linear structure 2222. In addition, in order to further increase the length of the linear structure 2222, each linear structure 2222 may also have a part 2224 that is parallel to a side of the square. The parallel part 2224 may significantly increase the length of the linear structure 2222, thereby increasing the inductance value of the pattern unit 2220. [000205] FIG.8A is a front view of a grid reflector 170 with a frequency selective section 223 and unit cells 171 according to another embodiment of the present disclosure. FIG.8B is a schematic front view of a single unit cell 171 showing pattern unit 2230 in the frequency selective section 223 shown in FIG.8A. As shown, the pattern unit 2230 may be substantially square or rectangular, similar to the perimeter discussed with respect to FIGS. 7A/7B. The pattern unit 2230 may include a sheet structure 2231 and a plurality of linear structures 2232, and each linear structure 2232 may extend outward from a respective concave portion 2233 of the sheet structure 2231. The sheet structure 2231 may have a substantially square shape. Each linear structure 2232 may be electrically connected to a respective linear structure 2232 in an adjacent pattern unit 2230. The sheet structure 2231 forms a capacitor structure, and the linear structures 2232 forms inductor structures. In addition, in order to increase the length of each linear structure 2232, the linear structure 2232 may also have parts 2234 and 2235 that extend parallel to a side of the substantially square-shaped sheet structure 2231. With the two parallel parts 2234 and 2235, the length of each linear structure 2232 can be increased to increase the inductance value of the pattern unit 2230. Attorney Docket No.9833.6700.WO [000206] FIG. 9A is a schematic front view of a grid reflector 170 with a frequency selective section 224 according to still further embodiments of the present disclosure. FIG.9B is a schematic front view of a single unit cell 171 with the pattern unit 2240 in the frequency selective section 224 shown in FIG. 9A. As shown in FIGS. 9A, 9B, the pattern unit 2240 may include a sheet structure 2241 and a plurality of linear structures 2242. The linear structures 2242 extend outwardly from the corresponding sides of the substantially square- shaped sheet structure 2241 so as to be electrically connected to the linear structures 2242 in adjacent pattern units 2240. The sheet structure 2241 forms a capacitor structure, and the linear structures 2242 form respective inductor structures. [000207] In some embodiments according to the present disclosure, one or more, even each, unit cell/pattern unit 171 may have a different size. FIG.10 is a schematic front view of a grid reflector 170 with a frequency selective section 225 according to an embodiment of the present disclosure, in which the area of the sheet structure 2251 in each pattern unit gradually decreases from left to right. Correspondingly, the length of the linear structure 2252 in each pattern unit gradually increases from left to right. Of course, the present disclosure is not limited thereto, and the area of the sheet structure 2251 in each pattern unit may also gradually increase from left to right and/or have other configurations. Correspondingly, the length of the linear structure 2252 in each pattern unit gradually decreases from left to right. In addition, the area of the sheet structure 2251 and the length of the linear structure 2252 in each pattern unit may also change in other ways, for example, may alternately increase and decrease, etc. By reasonably setting parameters such as the area of the sheet structure 2251 and the length of the linear structure 2252, it is possible to achieve the passage of electromagnetic waves within a predetermined frequency range by using the example embodiment of a frequency selective section 225 shown in FIG.10. [000208] In some embodiments according to the present disclosure, the grid reflector 170 can have a frequency selective section that may alternatively or also have a plurality of unit cells/pattern units 171 with different configurations. FIG.11 shows a grid reflector 170 with a frequency selective section 226 having pattern units/unit cells 171 of different configurations according to an embodiment of the present disclosure. As shown in FIG. 11, the frequency selective section 226 may include pattern units 2260 and 2270 with two different configurations. The pattern units 2260 and 2270 may be arranged alternately. It should be noted that FIG. 11 does not show the specific configurations of the pattern units 2260 and 2270. Those skilled in the art can design suitable configurations and parameters such as the spacing of the pattern units according to the teaching of the present disclosure such that the Attorney Docket No.9833.6700.WO frequency selective section 226 shown in FIG. 11 can allow electromagnetic waves within a predetermined frequency range to pass. For example, each unit cell 171 and/or pattern unit 2260 may have any of the pattern unit configurations discussed above and each pattern unit 2270 may have any of the pattern unit configurations discussed above. [000209] In addition, although the pattern units in the illustrated embodiments are rectangular or substantially square, the present disclosure is not limited thereto. The unit cells/pattern unit 171 may have various shapes, such as triangle, rectangle, rhombus, pentagon, hexagon, circle, oval, and the like and combinations of different shapes for different unit cells. [000210] In some embodiments according to the present disclosure, the frequency selective section may be configured as a slotted frequency selective section, which may be achieved by periodically opening slots of metal units on a metal plate and forming various pattern units periodically arranged as shown in FIGS.5A to 11, for example. To this end, in an embodiment according to the present disclosure, a slot may be formed by punching or laser direct structuring (LSD) at a corresponding position of the metallic main body 21 to form a frequency selective section. The main body 21 and the frequency selective section 22 may be integrally formed of a metal plate, thereby ensuring that the formed frequency selective reflector 20 has sufficient strength. In other embodiments, the main body 21 and the frequency selective section 22 may be formed as separate components and then coupled or fixed together in an appropriate manner to form the grid (frequency selective) reflector 170. In some embodiments, the main body 21 and the frequency selective section 22 may also be made of different materials. [000211] In some embodiments according to the present disclosure, the grid reflector 170 can comprise a patch type frequency selective section, which may be achieved by forming periodically arranged metal pattern units on a substrate. The plurality of metal pattern units may be formed on the substrate by a selective electroplating process or a metal ink transfer printing process. In some embodiments, the substrate may be formed of plastic, and the metal pattern unit may be formed of metal materials such as copper, aluminum, gold, and silver. In order to increase the strength of the frequency selective reflector 170, the substrate may be formed of high-strength plastic. [000212] Turning now to FIGS. 12A-22, the grid reflector 170 can be configured with the unit cells 171 having an open center interior 172 devoid of metal and each unit cell 171 can include a metal perimeter 173. The grid reflector 170 can be provided as a single layer of sheet metal providing the unit cells 171 with the open centers or interiors 172 devoid of metal. Attorney Docket No.9833.6700.WO [000213] In some embodiments, the open centers 172 can be open to atmosphere/local environmental conditions. In other embodiments, the grid reflector 170 comprises a dielectric cover 271 (FIG. 23C) extending over the unit cells 171. The dielectric cover 271 can comprise fiberglass, a printed circuit board, or a plastic, such as polymer or copolymer. The dielectric cover 271 may improve low and/or mid band reflection. The dielectric cover 271 (FIG. 23C) may be attached to the grid reflector 170 to extend over (in front of and/or behind) each unit cell 171. [000214] The grid reflector 170 is configured to allow RF energy (electromagnetic waves) to pass through at one or more first defined frequency range and is also configured to reflect RF energy at a different second frequency range/band. [000215] A pair 171p of neighboring unit cells 171 can share a metal (line) segment 174 defining part of each unit cells’ outer perimeter 173. As shown, one unit cell 171c can be surrounded by a plurality of neighboring unit cells 171n, each neighboring unit cell 171n (shown as four neighboring unit cells 171n in this embodiment) sharing a perimeter metal line segment 174 with the center cell 171c. [000216] Referring to FIGS. 13A and 13B, in this example, the grid reflector 170 comprises at least one shaped metal region 1173 positioned about the perimeter 173 of the respective unit cells 171’. A shared metal segment 174, which can be a line of metal, forming part of respective perimeters 173 of neighboring 171n unit cells 171, can merge into or extend across least one shaped metal segment 1173. The shaped metal region 1173 can extend beyond the shared metal segment 174 such that opposing inner free ends 1173e can project inwardly toward the center space 172 and terminate at a location laterally and/or longitudinally offset from a center of a respective unit cell 171’. [000217] FIGS.14A and 14B illustrate another example of a grid reflector 170. Similar to FIGS. 13A, 13B, the grid reflector 170 comprises at least one shaped metal region 1173 positioned about the perimeter 173 of the respective unit cells 171’’. The shaped metal region 1173 can have an open interior space 1173i rather than the closed shaped metal region shown in FIGS.13A/13B. The shaped metal region 1173 can have a perimeter 1173p surrounding an open interior space 1173i that is smaller than the open space 172 of the unit cells 171. The shaped metal region 1173 can have opposing first and second ends 1173e and first end 1173e extends into the first unit cell and the second end 1173e extends into the second unit cell. Grid reflectors 170 with shaped metal regions 1173 with open interior spaces 1173i can reduce a weight of the reflector while also providing increased current path. Attorney Docket No.9833.6700.WO [000218] Referring to FIGS.13A, 13B, 14A, 14B, the shared metal segment 174 of the metal perimeter line 173 shared by neighboring 171n unit cells 171 can attach to at least one shaped metal region 1173 (above and below or to the right and left side thereof) and a first part of the shaped metal region 1173 resides inside a first unit cell 171 of the pair 171p of neighboring unit cells and a second part of the shaped metal region 1173 resides inside a second unit cell 171 of the pair 171p of neighboring 171n unit cells 171. [000219] The shaped metal regions 1173 are shown as rectangles but other shapes may be used. The rectangles, where used, can be oriented such that two long sides extend laterally, and two long sides extend longitudinally, about a perimeter 173 of respective unit cells 171. [000220] In some embodiments, the unit cells 171 comprise perimeters 173 with corners 173c and the grid reflector 170 can be configured so that a shaped metal region 1173 extends along a sub-length of a shared metal segment 174 (of immediately adjacent, neighboring unit cells 171), shown as metal line segments, of the perimeter 173 between a pair of spaced apart corners 173c. [000221] Referring to FIGS. 13B and 14B, in some embodiments, the shaped metal regions 1173 are configured so that a first axis of symmetry A ₁ -A ₁ aligns with the shared metal line segment 174 of the metal perimeter 173. The shaped metal regions 1173 can also be configured so that a second axis of symmetry A2-A2, that is perpendicular to the first axis of symmetry A ₁ -A ₁ , aligns with a center point Cp of a respective unit cell 171. [000222] FIGS.15A, 15B, 16A, 16B illustrate additional examples of the grid reflector 170 with metal shaped regions 1173’ spaced apart about the perimeter 173 of the unit cells 171’’’, 171’’’’, respectively, and with the open center space 172 of the unit cells. In these embodiments, the shaped metal regions 1173’ have a circular outer perimeter 1173p when in the grid 170 and arcuate when shown with respect to a single unit cell 171’’’ (FIGS. 15B, 16B). FIGS.16A, 26B illustrate that the shaped metal regions 1173’ can have an open interior space 1173i. The open interior space 1173i can be circular as shown or have other shapes such as polygonal, oval, triangular and the like. As before a pair 171p of neighboring 171n cells 171’’’ (FIG. 15A) or 171’’’’ (FIG. 16A) share a metal line segment 174 forming part of a respective perimeter 173. [000223] FIGS.17A, 17B, 18A and 18B illustrate additional example grid reflectors 170. In these embodiments, the unit cells 171’’’’’ each have a hollow “X” shape defining an open space 172 with an open center point Cp and open angular spaces that cross the center point Cp to form the “hollow” X shape. The metal perimeter 173 can have an inner perimeter 173i that has a different shape than an outer perimeter 173o forming the metal perimeter 173. The inner Attorney Docket No.9833.6700.WO perimeter 173 is shaped to provide the angular spaces of the open center 172. The shaped metal region 1173’’ positioned about the perimeter 173 can comprise a triangular shape for a respective unit cell 171’’’’’ with a long side thereof that faces another long side of a neighboring triangular shape 1173’ in the grid reflector 170. The shaped metal regions 1173’ can define part of a perimeter segment 174 of neighboring unit cells 171’’’’’. FIGS.18A, 18B illustrate that the shaped metal region 1173’ can have an open or hollow interior space 1173i forming “diamond” shape two-dimensional cutouts in the grid reflector 170. [000224] FIGS. 19A-19D illustrate additional examples of grid reflectors 170 with different shapes of the open interior spaces 174 of respective unit cells 171, shown as circular, diamond and polygonal, such as octagonal and heptagon. [000225] The unit cells 171 of the grid reflectors 170 can have other shapes and may be symmetrical. [000226] In some embodiments, the unit cells 171 may have asymmetric configurations. [000227] The grid reflector 170 can be configured so that the array of unit cells 171 can be asymmetrical about one or more axis. [000228] The metal perimeters of respective unit cells 171 can be sufficiently narrow to accommodate the angle of incidence of RF energy from radiating elements behind the grid reflector while allowing the RF energy to propagate forward while concurrently reflecting RF energy from radiating elements in front of the grid reflector 170 as the RF energy from the radiating elements behind the grid reflector 170 may propagate forward in a number of angular directions. [000229] Referring to FIGS.20-22, the grid reflector 170 can be configured so that there are different densities of unit cells 171 at different locations. In some embodiments the grid reflector 170 can be configured so that unit cells 171 may be asymmetric about one or more axes to, for example, improve cross-polarization performance. The metal perimeters 173 can vary in width about a respective perimeter of a unit cell 171. [000230] FIG. 20 illustrates a greater density of unit cells 171 at left and right-side portions, 170r, 170l relative to a medial portion 170m. FIG.20 also illustrates that unit cells 171 located at a medial portion 170m of the grid reflector 170, can have a larger surface area, height and/or width, shown as a common height dimension and different width dimensions (and with larger center spaces 172) than unit cells 171 located at the left and right side portions 170r, 170l. [000231] FIG.21 illustrates a greater density of unit cells 171 at a medial portion 170m of the grid reflector 170 relative to the unit cells 171 at right and/or left side portions 170r, Attorney Docket No.9833.6700.WO 170l. FIG. 21 also illustrates that unit cells 171 located at right and left side portions 170r, 170l can have a larger surface area, height and/or width, shown as a common height and larger width (with larger center spaces 172) than unit cells 171 located at the medial portion 170m. [000232] FIG.22 illustrates a greater density of unit cells 171 at a medial portion 170m of the grid reflector 170 relative to the unit cells 171 at right 170r and/or left side 170l portions. FIG.22 also illustrates that unit cells 171 located at right and left side portions) 170r, 170l can have a larger surface area, height and width, (with larger center spaces 172) than unit cells 171 located at the medial portion 170m. [000233] The grid reflector 170 can be configured to merge into or attach to longitudinally extending right and left side 214s of (solid) surfaces of the primary reflector 214 at one or more locations, such as along longitudinally extending outer sides 170s (FIG. 15A). The grid reflector 170 can be configured to have different unit cell configurations and/or sizes at different locations. [000234] When configured to allow high-band energy to pass through the grid reflector 170, thick/wide grid perimeters 173 surrounding the open spaces 172 of the unit cells 171 should be avoided to reduce blockage at off-angle scans at high band. [000235] In some embodiments, the grid reflector 170 of the passive antenna assembly 190 can be configured to act like a High Pass Filter essentially allowing low band energy to completely reflect as the grid is formed by a sheet of metal while allowing higher band energy, for example, about 3.5 GHz or greater, to pass through, typically substantially completely pass through. Thus, the grid reflector 170 is transparent or invisible to the higher band energy and a suitable out of band rejection response can be achieved. [000236] Turning now to FIGS.23A, 23B and 24, an example passive antenna assembly 190 is shown. The grid reflector 170 can merge into the primary reflector 214 that extends longitudinally and laterally. The primary reflector 214 may have a longitudinal length that is greater than a longitudinal length of the grid reflector 170. The primary reflector 214 can have a solid reflection surface for antenna elements residing in front of the primary reflector 214 and may reside over operational components 314, such as filters, tilt adjusters and the like. [000237] The grid reflector 170 can reside a distance in a range of 1/8 wavelength to ¼ wavelength of an operating wavelength behind the low band dipoles 222, in some embodiments. The term "operating wavelength" refers to the wavelength corresponding to the center frequency of the operating frequency band of the radiating element, e.g., a low band radiating element 222. The grid reflector 170 can reside a distance in a range of 1/10 wavelength to 1/2 wavelength of an operating wavelength in front of the high band radiating Attorney Docket No.9833.6700.WO elements 1195, in some embodiments. By way of example, in some particular embodiments, the grid reflector 170 can reside a physical distance of 0.25 inches and 2 inches from a ground plane or reflector 1172 that is behind a mMIMO array of radiating elements 1195 of an active antenna module 110 (FIG.25, 26A, 26B). Other placement positions may be used. [000238] In some embodiments, the ground plane or reflector 1172 of the active antenna module 110 can be electrically coupled to the grid reflector 170 and/or primary reflector 214 of the base station antenna 100, such as galvanically and/or capacitively coupled. In other embodiments, the ground plane or reflector 1172 of the active antenna module 110 is not electrically coupled to the grid reflector 170 and/or primary reflector 214. [000239] Referring to FIG.23A, the grid reflector 170 can have a longitudinal extent “L” and a lateral extent “W”. The longitudinal extent L can extend a distance that is greater than the lateral extent W. The longitudinal extent L can be less than the lateral extent W. The grid reflector 170 has a front side 170f that faces the front side 100f of the housing 100h/radome 111f. [000240] The antenna assembly 190 comprises multiple arrays of radiating elements, typically provided in six columns, with radiating elements that extend forwardly from the front side 170f of the reflector 170, with some columns of radiating elements continuing to extend in front of the primary reflector 214. The arrays of radiating elements of the antenna assembly 190 may comprise radiating elements 222 that are configured to operate in a first frequency band and radiating elements 232 that are configured to operate in a second frequency band. Other arrays of radiating elements may comprise radiating elements that are configured to operate in either the second frequency band or in a third frequency band. The first, second and third frequency bands may be different frequency bands (although potentially overlapping). In some embodiments, low band antenna element 222 with dipole arms can reside in front of the grid reflector 170, typically along right and left side portions 170s of the grid reflector 170 and/or primary reflector sides 214s. [000241] FIG.23C illustrates that the grid reflector 170 can be provided as a reflector body or assembly with a first grid reflector 170 ₁ and a second grid reflector 170 ₂ that are longitudinally spaced apart, typically separated by a primary reflector 214 having a continuous surface devoid of the grid unit cells 171. [000242] As discussed above, FIG. 23C also illustrates that a dielectric cover 271 may be attached to the grid reflector 170 and extend across the unit cells 171. The dielectric cover 271 can have a dielectric constant that is at least 1 and may in a range of 1-6, in some embodiments, such as 1, 2, 3, 4, 5, 6 or any number in a range of 1-6, end points inclusive. Attorney Docket No.9833.6700.WO Dielectric material with higher value dielectric constants may be appropriate in some embodiments. [000243] The grid reflector 170 and the primary reflector 214 can be monolithically formed as a unitary (sheet) metal body in some embodiments. Alternatively, the grid reflector 170 and the primary reflector 214 can be provided as separate components that are directly or indirectly attached and electrically coupled together to provide a common electrical ground. The grid reflector 170 and the primary reflector 214 can both be sheet metal of the same or different thicknesses. [000244] In some embodiments, the grid reflector 170 can be provided by a different substrate than the primary reflector 214. In some embodiments, the grid reflector 170 can be provided as a printed circuit board with conductive patches forming the array of unit cells 171. The grid reflector 170 can be provided as a flex circuit board with conductive patches. The grid reflector 170 can be provided as a non-metallic substrate with metallized patches. [000245] Some of the radiating elements (discussed below) of the antenna 100 may be mounted to extend forwardly from the main reflector 214, and, if dipole-based radiating elements are used, the dipole radiators of these radiating elements may be mounted approximately ¼ of a wavelength of the operating frequency for each radiating element forwardly of the main reflector 214. The main reflector 214 may serve as a reflector and as a ground plane for the radiating elements of the base station antenna 100 that are mounted thereon. [000246] Still referring to FIGS.23A, 23B and 24, the passive antenna assembly 190 of the base station antenna 100 can include one or more arrays 220 of low-band radiating elements 222, one or more arrays 230 of first mid-band radiating elements 232, one or more arrays 240 of second mid-band radiating elements 242 and optionally one or more arrays 250 of high-band radiating elements 252. The radiating elements 222, 232, 242, 252, 1195 may each be dual- polarized radiating elements. Further details of radiating elements can be found in co-pending WO2019/236203 and WO2020/072880, the contents of which are hereby incorporated by reference as if recited in full herein. Some of the high band radiating elements, such as radiating elements 1195, can be provided as a mMIMO antenna array and may be provided in the active antenna module 110 rather than in the housing 100h of the base station antenna 100. [000247] The low-band radiating elements 222 can be mounted to extend forwardly from the main or primary reflector 214 and the grid reflector 170 and can be mounted in two columns to form two linear arrays 220 of low-band radiating elements 222. Each low-band linear array 220 may extend along substantially the full length of the antenna 100 in some embodiments. Attorney Docket No.9833.6700.WO [000248] The low-band radiating elements 222 may be configured to transmit and receive signals in a first frequency band. In some embodiments, the first frequency band may comprise the 617-960 MHz frequency range or a portion thereof (e.g., the 617-896 MHz frequency band, the 696-960 MHz frequency band, etc.). The low-band linear arrays 220 may or may not be used to transmit and receive signals in the same portion of the first frequency band. For example, in one embodiment, the low-band radiating elements 222 in a first linear array 220 may be used to transmit and receive signals in the 700 MHz frequency band and the low-band radiating elements 222 in a second linear array 220 may be used to transmit and receive signals in the 800 MHz frequency band. In other embodiments, the low-band radiating elements 222 in both the first and second linear arrays 220-1, 220-2 may be used to transmit and receive signals in the 700 MHz (or 800 MHz) frequency band. [000249] The first mid-band radiating elements 232 may likewise be mounted to extend forwardly from the main reflector 214 and/or grid reflector 170 and may be mounted in columns to form linear arrays 230 of first mid-band radiating elements 232. The linear arrays 230 of mid-band radiating elements 232 may extend along the respective side edges of the grid reflector 170 and/or the main reflector 214. The first mid-band radiating elements 232 may be configured to transmit and receive signals in a second frequency band. In some embodiments, the second frequency band may comprise the 1427-2690 MHz frequency range or a portion thereof (e.g., the 1710-2200 MHz frequency band, the 2300-2690 MHz frequency band, etc.). In the depicted embodiment, the first mid-band radiating elements 232 are configured to transmit and receive signals in the lower portion of the second frequency band (e.g., some or all of the 1427-2200 MHz frequency band). The linear arrays 230 of first mid-band radiating elements 232 may be configured to transmit and receive signals in the same portion of the second frequency band or in different portions of the second frequency band. [000250] The second mid-band radiating elements 242 can be mounted in columns to form linear arrays 240 of second mid-band radiating elements 242. The second mid-band radiating elements 242 may be configured to transmit and receive signals in the second frequency band. In the depicted embodiment, the second mid-band radiating elements 242 are configured to transmit and receive signals in an upper portion of the second frequency band (e.g., some, or all, of the 2300-2700 MHz frequency band). In the depicted embodiment, the second mid-band radiating elements 242 may have a different design than the first mid-band radiating elements 232. [000251] The high-band radiating elements 252 and/or 1195 can be mounted in columns in the upper medial or center portion of antenna 100 to form a multi-column (e.g., four or eight Attorney Docket No.9833.6700.WO column) array 250 of high-band radiating elements 252 and/or 1195. The high-band radiating elements 1195 may be configured to transmit and receive signals in a third frequency band. In some embodiments, the third frequency band may comprise the 3300-4200 MHz frequency range or a portion thereof. [000252] In the depicted embodiment, the arrays 220 of low-band radiating elements 222, the arrays 230 of first mid-band radiating elements 232, and the arrays 240 of second mid-band radiating elements 242 are all part of the passive antenna assembly 190, while the array 250 of high-band radiating elements 1195 are part of the active antenna module 110. It will be appreciated that the types of arrays included in the passive antenna assembly 190, and/or the active antenna module 110 may be varied in other embodiments. [000253] It will also be appreciated that the number of linear arrays of low-band, mid- band and high-band radiating elements may be varied from what is shown in the figures. For example, the number of linear arrays of each type of radiating elements may be varied from what is shown, some types of linear arrays may be omitted and/or other types of arrays may be added, the number of radiating elements per array may be varied from what is shown, and/or the arrays may be arranged differently. As one specific example, two linear arrays 240 of second mid-band radiating elements 242 may be replaced with four linear arrays of ultra-high- band radiating elements that transmit and receive signals in a 5 GHz frequency band. [000254] At least some of the low-band and mid-band radiating elements 222, 232, 242 may each be mounted to extend forwardly of and/or from the grid reflector 170 or the main reflector 214. [000255] Each array 220 of low-band radiating elements 222 may be used to form a pair of antenna beams, namely an antenna beam for each of the two polarizations at which the dual- polarized radiating elements are designed to transmit and receive RF signals. Likewise, each array 232 of first mid-band radiating elements 232, and each array 242 of second mid-band radiating elements 242 may be configured to form a pair of antenna beams, namely an antenna beam for each of the two polarizations at which the dual-polarized radiating elements are designed to transmit and receive RF signals. Each linear array 220, 230, 240 may be configured to provide service to a sector of a base station. For example, each linear array 220, 230, 240 may be configured to provide coverage to approximately 120º in the azimuth plane so that the base station antenna 100 may act as a sector antenna for a three-sector base station. Of course, it will be appreciated that the linear arrays may be configured to provide coverage over different azimuth beamwidths. While all of the radiating elements 222, 232, 242, 252, 1195 can be dual- polarized radiating elements in the depicted embodiments, it will be appreciated that in other Attorney Docket No.9833.6700.WO embodiments some or all of the dual-polarized radiating elements may be replaced with single- polarized radiating elements. It will also be appreciated that while the radiating elements are illustrated as dipole radiating elements in the depicted embodiment, other types of radiating elements such as, for example, patch radiating elements may be used in other embodiments. [000256] Some or all of the radiating elements 222, 232, 242, 252, 1195 may be mounted on feed boards that couple RF signals to and from the individual radiating elements 222, 232, 242, 252, 1195, with one or more radiating elements 222, 232, 242, 252, 1195 mounted on each feed board. Cables (not shown) and/or connectors may be used to connect each feed board to other components of the antenna 100 such as diplexers, phase shifters, calibration boards or the like. [000257] RF connectors or "ports" 140 can be mounted in the bottom end cap 130 that are used to couple RF signals from external remote radio units (not shown) to the arrays 220, 230, 240 of the passive antenna assembly 190. Two RF ports can be provided for each array 220, 230, 240 namely a first RF port 140 that couples first polarization RF signals between the remote radio unit and the array 220, 230, 240 and a second RF port 140 that couples second polarization RF signals between the remote radio unit and the array 220, 230, 240. As the radiating elements 222, 232, 242 can be slant cross-dipole radiating elements, the first and second polarizations may be a -45º polarization and a +45º polarization. [000258] A phase shifter may be connected to a respective one of the RF ports 140. The phase shifters may be implemented as, for example, wiper arc phase shifters such as the phase shifters disclosed in U.S. Patent No.7,907,096 to Timofeev, the disclosure of which is hereby incorporated herein in its entirety. A mechanical linkage may be coupled to a RET actuator (not shown). The RET actuator may apply a force to the mechanical linkage which in turn adjusts a moveable element on the phase shifter in order to electronically adjust the downtilt angles of antenna beams that are generated by the one or more of the low-band or mid-band linear arrays 220, 230, 240. [000259] It should be noted that a multi-connector RF port (also referred to as a "cluster" connector) can be used as opposed to individual RF ports 140. Suitable cluster connectors are disclosed in U.S. Patent Application Serial No. 16/375,530, filed April 4, 2019, the entire content of which is incorporated herein by reference. [000260] Referring to FIGS.23A, 23B, feed boards 1200 can be provided in front of or behind the side segments 214s of the primary reflector 214. The feed boards 1200 connect to feed stalks 221 (or 222f) of radiating elements 222 (such as low band elements). The feed stalks 221 can be angled feed stalks that project outwardly and laterally inward to position the Attorney Docket No.9833.6700.WO front end of the feed stalks 221 closer to center of the reflector 170 than a rearward end. The feed boards 1200 can be coupled and/or connected to the grid reflector 170 or to the primary reflector 214. [000261] The radiating elements 222 can be dipole elements configured to operate in some or all the 617-960 MHz frequency band. A feed circuit comprising a hook balun can be provided on the feed stalk 221. Further discussions of example antenna elements including antenna elements comprising feed stalks can be found in U.S. Provisional Patent Application Serial Numbers 63/087,451 and 62/993,925 and/or related utility patent applications claiming priority thereto, the contents of which are hereby incorporated by reference as if recited in full herein. [000262] Some or all of the low or mid-band radiating elements 222, 232, respectively, may be mounted on the feed boards 1200 and can couple RF signals to and from the individual radiating elements 222, 232. Cables (not shown), microstrips and/or connectors may be used to connect each feed board to other components of the base station antenna 100 such as diplexers, phase shifters, calibration boards or the like. [000263] Turning now to FIG.25, an example active antenna module 110 is shown. The active antenna module 110 can include an RRU (remote radio unit) unit 1120 with radio circuitry. The active antenna module 110 can also include a filter and calibration printed circuit board assembly 1180, and an antenna assembly 1190 comprising a reflector or ground plane of a printed circuit board 1172 behind radiating elements 1195. The antenna assembly 1190 may also include phase shifters 1191, which may alternatively be part of the filter and calibration assembly 1180. The radiating elements 1195 can be provided as a massive MIMO array. The RRU unit 1120 is a radio unit that typically includes radio circuitry that converts base station digital transmission to analog RF signals and vice versa. One or more of the radio unit or RRU unit 1120, the antenna assembly 1190 or the filter and calibration assembly 1180 can be provided as separate sub-units that are attachable (stackable). The RRU unit 1120 and the antenna assembly 1190 can be provided as an integrated unit, optionally also including the calibration assembly 1180. Where configured as sub-units, different sub-units can be provided by OEMs or cellular service providers while still using a common base station antenna housing 100h and passive antenna assembly 190 thereof. The antenna assembly 1190 can couple to the filter and calibration board assembly 1180 via, for example, pogo connectors 111. Other connector configurations may be used for each of the connections, such as, for example 3-piece SMP connectors. The RRU unit 1120 can also couple to the filter and calibration board assembly 1180 via pogo connectors 111 thereby providing an all blind-mate connection Attorney Docket No.9833.6700.WO assembly without requiring cable connections. Alignment of the cooperating components within a tight tolerance may be needed to provide suitable performance. In other embodiments, the radio circuitry can be provided with the antenna assembly as a single integrated unit. [000264] The antenna module 110 can include a radome 119 and optionally a second radome 1119. The second radome 1119 covers the first radome 119 for aesthetic purposes and can be removed at installation, in some embodiments. [000265] FIGS. 26A and 26B illustrate example embodiments of the base station antennas 100 and the active antenna modules 110. FIG.26A illustrates that the rear 100r of the base station antenna 100 can have a flat surface and the active antenna assembly 1190 can be configured to face the rear 100r with the radomes 119, 111r therebetween and with the grid reflector 170 in front of the radiating elements 1195. FIG.26B illustrates that the rear 100r of the base station antenna 100 can have recessed segment 102 and sized to receive the radome 119 of the active antenna unit 110, again with the radiating elements 1195 behind and facing the grid reflector 170. [000266] FIG.27 is a simplified sectional view of an example base station antenna 100 with grid reflector 170 aligned with an active antenna module 110. [000267] The grid reflector 170 can provide a wider band pass for high band, a higher suppression for low band and a large incident angle of support over cutout reflectors. [000268] Turning now to FIG. 28A, the grid reflector 170 is shown with two linear columns of low band radiating elements 222 extending forward thereof. The linear columns extend over the primary reflector 214 below the grid reflector 170. The grid reflector 170 can be coupled to the right and left side segments 214s of the primary reflector 214 or can be held by a main body 21 of the grid reflector and coupled to the primary reflector 214. FIG. 28B shows an example rear side of the grid reflector 170 and primary reflector 214. [000269] FIG.28C illustrates the grid reflector 170 coupled to an internal, forward-facing surface of the rear radome 111r, rear 100r of the housing 100h. The grid reflector 170 can be in a different plane that is behind the plane of the primary reflector 214. The grid reflector 170 can be electrically coupled to the primary reflector 214 so that both are at a common ground. The rear radome 111r can cooperate with the grid reflector 170 for dielectric loading thereof. The term “dielectric loading” means that the rear radome 111r, 100r is configured to cooperate with the grid reflector 170 (e.g., FSS) via spacing and material having a dielectric constant to reduce or minimize reflections at a band that the grid reflector and/or FSS is configured to transmit through. Attorney Docket No.9833.6700.WO [000270] The grid reflector 170 may be provided as a flex circuit that conformably attaches to the internal surface of the rear (wall) 100r of the radome 111r. A double-sided tape, adhesive, bonding material or other attachment configuration may be used to attach the grid reflector 170 to the rear radome 111r. The rear radome 111r can have a dielectric constant in a range of 1-3. [000271] In other embodiments, referring to FIG.28D, that the grid reflector 170 can be attached to the primary reflector 214, shown as the spaced apart right and left side segments 214s of the primary reflector 214 in this figure. A primary portion 170p of a front or forwardly facing surface 170f of the grid reflector 170 can be parallel to the primary surface 214p of the primary reflector 214. The primary surface of the grid reflector 170 can be co-planar with the primary surface 214p of the primary reflector 214. In other embodiments, the grid reflector 170 can reside behind a primary surface of the primary reflector 214 in a different plane. [000272] Turning now to FIGS.28E, 28F and 28G, the base station antenna 100 can have at least one matching layer 310 that can reside behind a primary surface of the front reflector 214 and in front of a grid reflector 170. The matching layer 310 that is behind the primary surface of the front reflector 214 can be referred to as a “back” matching layer 310b. In some embodiments, the back matching layer 310b can be closely spaced apart from the rear radome 111r and/or the grid reflector 170, typically a distance in a range of 0.1 mm to 25 mm, such as about 10-15 mm, and can be at about 10 mm, about 11 mm, and about 12 mm. [000273] Still referring to FIGS. 28E, 28F, 28G, in some embodiments, at least one additional matching layer 310 can also reside forward of the primary reflector 214 and at least one matching reflector can reside behind the right and left forward sides 214s of the front reflector 214. [000274] The primary reflector 214 can have the spaced apart right and left side segments 214s discussed above, which can bend rearward to define back segments 214b. The grid reflector 170 can be attached to the back segments 214b and/or the internal surface 111i of the rear radome 111r. The grid reflector 170 can be provided as a multi-layer printed circuit board and/or a flex circuit. [000275] Turning now to FIGS. 29A-29D, the grid reflector 170 can be provided as a separate piece from the primary reflector 214. The grid reflector 170 can be provided as sheet metal grid reflector. The grid reflector 170 can have a coupling segment 170c for attaching to the primary reflector 214. The grid reflector 170 can be electrically coupled to the primary reflector 214. The grid reflector 170 can be co-planar with the primary reflector 214. Attorney Docket No.9833.6700.WO [000276] FIG. 29A also illustrates that the base station antenna 100 can include a plurality of projecting matching layer support posts 300 that can support at least one matching layer 310 (FIGS.28G, 37, for example). [000277] FIGS.29B and 29C illustrate that the coupling segment 170c can include right and left side arms that extend longitudinally and that are laterally spaced apart. The right and left side arms can attach to adjacent segments of the primary reflector 214. The grid reflector 170 can be positioned rearward of the primary surface 214p of the primary reflector 214, closer to the rear radome 111r. In some embodiments, similar to the printed circuit board configuration of the grid reflector 170 discussed with respect to FIG.28G, the back matching layer 310b can be closely spaced apart from the rear radome 111r and/or the grid reflector 170, typically a distance in a range of 0.1 mm to 25 mm, such as about 10-15 mm, and can be at about 12 mm. [000278] Referring to FIGS. 29C-29E, the base station antenna 100 can include two matching layers that reside behind the primary surface of the primary reflector 214, labeled as 310b ₁ , 310b ₂ in FIG.29E. The first back matching layer 310b ₁ can reside closer to the primary surface 214p of the primary reflector 214 than the second back matching layer 310b ₂ . The first and second back matching layers 310b ₁ , 310b ₂ can be stacked but spaced apart in a front to back direction, a distance that is in a range of 10-100 mm, such as about 60-70 mm, in some embodiments. [000279] FIGS. 30-33 illustrates that the base station antenna 100 can have provide an integrated reflector 1214 that provides both the primary reflector 214 and the grid reflector 170 as a unitary (monolithic) structure. [000280] FIG.31 illustrates that the grid reflector 170 can have a three-dimensional body 170b with unit cells 171 extending on the front surface 170f and also on rearwardly extending walls 170w. The front surface 170f can extend laterally and can merge into right and left side corners that connect to the rearwardly extending walls 170w. The rearwardly extending walls 170w can be orthogonal to the front surface 170f. The three-dimensional body 170b can be provided separate from the primary reflector 214. [000281] As shown in FIGS. 34 and 35, the three-dimensional body 170b can also be configured to provide isolation walls 350 that project rearwardly from a rear facing surface and/or that project forwardly from a front facing surface 170f. The isolation walls 350 can be metal, metallized or provided as frequency selective surface/substrate reflector configuration. As is also shown, the side walls 170w can extend both forwardly and rearwardly of the front surface 170f of the grid reflector 170, orthogonal thereto. The forward projection segment of Attorney Docket No.9833.6700.WO the side walls 170s can be metal, metallized, or provided as a frequency selective surface/substrate. [000282] FIGS.36 and 37 illustrate that the base station antenna 100 can have first and second reflectors 170 ₁ , 170 ₂ that can both be configured as grid reflectors 170 and that are stacked in a front-to-back orientation, one at least partially in front of another, inside the base station antenna housing 100h. A plurality of linear columns of radiating elements 222 can project forwardly of the first reflector 170 ₁ . The second grid reflector 170 ₂ can reside closer to the rear 100r of the base station antenna 100 than the first grid reflector 170 ₁ . [000283] The first grid reflector 170 ₁ and the second grid reflector 170 ₂ can have different primary substrates and can be tuned to reflect and propagate RF energy in the same or in different frequency bands. One of the first grid reflector 170 ₁ or the second grid reflector 170 ₂ can be configured as a metal grid reflector 170 and the other of the first grid reflector 170 ₁ or the second grid reflector 170 ₂ can be configured as a non-metallic substrate with metal patches, such as a multi-layer circuit board or a flex circuit which may improve low band reflection. [000284] The first grid reflector 170 ₁ can comprise unit cells 171 configured to pass RF energy in a second frequency band and absorb and/or reflect at least one of RF energy in a first frequency band and optionally also absorb and/or reflect RF energy in a third frequency band. The third frequency band can encompass frequencies between the first and second frequency bands. [000285] Referring to FIG. 37, at least one of the first reflector 170 ₁ and the second reflector 170 ₂ can be configured to mount at least some of the matching layer support posts 300. As shown, at least one matching layer 310 (shown as two matching layers, stacked and spaced apart in a front-to-back direction) can reside behind the first reflector 170 ₁ . The support posts 300 for supporting that matching layer 310 can project rearward of the first reflector 170 ₁ and/or forward of the second reflector 170 ₂ . Alternatively, the support posts 300 can project inwardly from the sides 100s of the housing 100h to mount a respective matching layer 310 (not shown). [000286] Still referring to FIG.37, the base station antenna 100 can have a plurality of matching layers 310 in front of the first reflector 170 ₁ and a plurality of matching layers behind the first grid reflector 170 ₁ . As shown, there are four matching layers 310 ₁ , 310 ₂ , 310 ₃ , 310 ₄ , with first and second matching layers 310 ₁ , 310 ₂ behind and 310 ₃ , 310 ₄ , in front of the grid reflector 170 ₁ . [000287] It is also contemplated that the base station antenna 100 can have a grid reflector 170 without any matching layers 310 by adjusting spacing of high band radiating elements in Attorney Docket No.9833.6700.WO the active antenna module 110 and the low band radiating elements 222 relative to each other and the front radome 100f and/or back radome 100r using a low dielectric constant radome material, for example. [000288] Referring to FIGS.38A and 38B, the grid reflector 170 can have a grid of unit cells 171 with a first subset 171a of the unit cells 171 tuned for blocking and/or reflecting RF energy in a first frequency band while allowing RF energy in a second frequency band to propagate therethrough. The grid reflector 170 can also have a second subset 171b of the unit cells 171 tuned for blocking and/or reflecting RF energy in the first frequency band and RF energy in a third frequency band. The third frequency band comprises frequencies between the first and second frequency bands. [000289] The first subset 171a of the unit cells 171 can be positioned at an upper portion of the base station antenna 100. The second subset 171b of the unit cells 171 can include unit cells that are below and/or to right and left sides of the first subset 171a of the unit cells 171. The grid reflector 170 can include a region 171r, optionally with a third subset 171c of the unit cells 171, that can be tuned for blocking and/or reflecting RF energy in the first frequency band, the second frequency band and the third frequency band. The region 171r can be a closed metal or metallized surface and does not require unit cells and can provide increased rigidity/structural support. Some of the unit cells 171 in the second subset 171b of the unit cells 171 can be to the left side and/or right side of the first subset of the unit cells 171a. [000290] The first subset 171a of the unit cells 171 can reside behind low band radiating elements 222 and in front of high band radiating elements 1195 (e.g., a mMIMO array). The second subset 171b of the unit cells 171 can reside behind mid-band 232 radiating elements. The first frequency band can be low band, the second frequency band can be a high band frequency band, the third frequency band can be mid-band with at least some frequencies between the first and second frequencies. [000291] The reflector 170 can be provided as a three-dimensional structure or body 170b that includes unit cells 171 that are positioned rearwardly of some of the first subset 171a of the unit cells 171. [000292] Turning now to FIGS. 39A-39C, as discussed above with respect to 28C, the grid reflector 170 can be provided as a printed circuit board reflector, optionally a flex circuit, that can be attached or coupled to the rear radome 111r. The base station antenna 100 can also include at least one back matching layer 310. The at least one matching layer 310 can include at least one back matching layer 310b that is positioned behind a primary surface of the primary reflector 214 and in front of the grid reflector 170. The at least one back matching layer 310b Attorney Docket No.9833.6700.WO can reside a distance “d” in front of the rear radome 111r and/or grid reflector 170 where “d” is a distance in a range of 0.1 mm to 25 mm, such as about 10-15 mm, and can be at about 10 mm, about 11 mm, and about 12 mm. [000293] FIG.40 illustrates that the base station antenna 100 can comprise at least four matching layers 310 ₁ -310 ₄ , stacked in a front to back direction, in the base station antenna housing 100h. Two of the matching layers 310 ₃ , 310 ₄ can be back matching layers 310b ₁ , 310b ₂ as shown. The grid reflector 170 can be co-planar with (the primary surface of the) the primary reflector 214. The most rearward back reflector 310b ₂ can reside adjacent the rear radome 111r, typically at a distance of 1-20 mm from the rear radome 111r. The two center or medial matching layers 310 ₂ , 310 ₃ , can be provided on opposing primary surfaces of the grid reflector 170, and in close proximity thereto, such as within about 2-10 mm thereof. The most forward matching layer 310 ₁ and the most rearward matching layer 310 ₄ can be equally spaced at a distance “D” from the grid reflector 170. The most forward matching layer 310 ₁ and the most rearward matching layer 310 ₄ can be equally spaced at a distance D1 from the corresponding medial matching layer 310 ₂ , 310 ₃ , respectively. [000294] The reflector 214 and/or the grid reflector (FSS) 170 can have back segments 214b, 170b that extend rearward of the primary surfaces 214, 170p, respectively, and reside adjacent the rear wall 100r and/or rear radome 111r. [000295] FIG.40 also illustrates that the grid reflector 170 can have side walls 170w that may extend rearward and can also comprise an array of apertures forming an FSS and/or grid reflector surface that can be orthogonal to the front radome 100f and/or front FSS surface 170f. The side walls 170w can be bent metal segments that extends off and behind the front surface 170f. [000296] FIGS.41A-41F illustrate additional example embodiments of stacked first and second reflectors 170 ₁ , 170 ₂ , spaced apart in a front to back direction of the base station antenna 100. An array of radiating elements 1195 can be positioned behind the first and second reflectors 170 ₁ , 170 ₂ , typically in an active antenna module 110. The array of radiating elements 1195 can comprise a mMIMO array of radiating elements as discussed hereinabove. [000297] Referring to FIGS.41C, 41D, 41E and 41F, the first reflector 170 ₁ can include a plurality of spaced apart cutouts 1201. Feed boards 1200 can extend across/along these cutouts 1201 and feed stalks 222f can connect a radiating element 222 to a feed board 1200. The feed boards 1200 can reside behind the primary front surface 170f of the reflector 170 ₁ , in some embodiments and can comprise a conductive (e.g., copper ground plane patterned Attorney Docket No.9833.6700.WO surface/circuit). The radiating elements 222 can be provided in different configurations and are not limited to the configurations shown. [000298] FIGS.41A, 41F, 41G illustrate that at least one of the first and second reflectors 170 ₁ , 170 ₂ can have a rearwardly extending portion defining at least a portion of a side wall 170w. A respective side wall 170w can be metal or provided as a printed circuit board or combinations thereof. The side walls 170w can be a bent portion of one or more of the first and second reflectors 170 ₁ , 170 _2. The side walls 170w can provide structural support for the reflector(s) 170 and/or radiating elements 222 mounted thereto. The side walls 170w may also or alternatively be configured to improve a radiation pattern provided by one or more of the radiating elements 222 and/or radiating elements 1195 in front of and/or behind the reflector(s) 170 ₁ , 170 ₂ . [000299] The first/front reflector 170 ₁ can be at a common plane with the primary reflector 214 (a front to back position that is aligned with the primary reflector 214). [000300] One or both of the first and second reflectors 170 ₁ , 170 ₂ can be configured so that the grid pattern extends across an entire lateral extent thereof. In other embodiments, the grid pattern may terminate at feed boards 1200 or solid metal surfaces thereof or coupled thereto. [000301] FIGS.41B, 41E illustrate that the first and second reflectors 170 ₁ , 170 ₂ can be provided without a bent side. One or both of the reflectors 170 ₁ , 170 ₂ can couple to internal mounting structures such as laterally extending and/or longitudinally rails to position them in alignment and in position in the base station antenna 100, for example. One or both of the first and second reflectors 170 ₁ , 170 ₂ can be coupled to a radome or surface of a housing provided by the base station antenna 100. [000302] Referring to FIGS.41A, 41F, and 41G, the side walls 170w may be solid metal (e.g., solid sheet metal) or may have metal patches and/or apertures 170a or cutouts extending between right and left segments 170s extending rearward and/or forward of the front primary surface 170f of the grid reflector 170. [000303] As is also shown in FIG.41G, the side walls 170w can extend both forwardly and rearwardly of the front surface 170f of the first and/or second grid reflector 170 ₁ , 170 ₂ , shown as extending forwardly and rearwardly of the front/first reflector 170 ₁ , orthogonal thereto. At least part of the side walls 170w can be formed by bending a segment of sheet metal forming the grid reflector 170 forward and/or rearward. Attorney Docket No.9833.6700.WO [000304] At least part of the side walls 170w can be provided by a metal grid or otherwise configured to provide an isolation surface/wall or an FSS, e.g., metal, metallized, or provided as a frequency selective surface/substrate. [000305] As shown in FIG. 41G, the side wall(s) 170w can have a front side segment 170wf that extends forward of a primary portion of a front 170f of the reflector 170. The side wall(s) 170w can also have a rear/back side segment 170wb that extends behind the front side wall segment with the primary portion of the front of the reflector extending laterally therebetween. The front side segment 170wf can have a different configuration from the back segment 170wb. The front side segment 170wf can be solid metal or formed of an FSS, in some embodiments. The rear/back segment 170wb can be solid, have apertures 170a and/or an array/ grid pattern of unit cells 171. [000306] Turning now to FIGS.42, 43A and 43B, the base station antenna 100 can have at least one grid reflector 170 with a right and/or left side 170s that defines a corresponding side wall 170w’ that projects forward from a front surface 170f of a primary portion 170p of the grid reflector 170 at an angle β. The angle β can be an oblique angle. The angle β can be in a Z direction of the base station antenna 100, with the Y direction corresponding to a generally vertical direction, subject to downtilt, and the X direction corresponding to a lateral direction. The angle β can be in a range of 35 degrees to 50 degrees in some embodiments. [000307] The angle β can be set according to operating parameters of different active antenna units 110 with different radios 1120, for example. In some embodiments, the angle β can be parallel/substantially parallel to incoming transmission waves. In some embodiments, the angle β can correspond to a scan angle of radiating elements such as those of an array of mMIMO radiating elements 1195 positioned behind the at least one grid reflector 170, typically in an active antenna unit 110 which may improve the performance of the radiating elements 1195. [000308] As shown, the base station antenna 100 can comprise first and second grid reflectors 170 ₁ , 170 ₂ that can be spaced apart a distance “d” inside the passive antenna housing 100h. The distance “d” can be in a range of 0.0 mm to about 30 mm. [000309] The first and second grid reflectors 170 ₁ , 170 ₂ can provide stable passive intermodulation performance with mMIMO. The first and second grid reflectors 170 ₁ , 170 ₂ can be configured to allow high band RF signal/radiation to propagate therethrough will providing rejection of low band and middle band RF signal from respective low band radiating elements 222 and mid band radiating elements 232. Attorney Docket No.9833.6700.WO [000310] Each of the first and second grid reflectors can have a side wall with a different configuration and/or angular orientation. For example, the first grid reflector 170 ₁ can have a side wall segment 170w’ that projects forward at an angle β ₁ and the second grid reflector 170 ₂ can have a side wall segment 170w’ that projects forward at an angle β2. [000311] In some embodiments, β1> β2. In some embodiments, β1< β2. In some embodiments, β ₁ =β ₂ . In some embodiments β ₁ and β ₂ are parallel oblique angles. [000312] Each of these first and second grid reflectors 170 ₁ , 170 ₂ , can extend a distance D1 and D2, respectively, forward of the ground plane and/or reflector 1172 of the active antenna unit 110. The distance D ₁ and/or D ₂ can be substantially equal to ¼ wavelength of a center operating frequency of the radiating elements 1195. The center operating frequency may be in a range of about 3.1 GHz to about 4.1 or 4.2 GHz, in some embodiments. [000313] The sides 170s can define forwardly projecting side walls 170w’ and each can include unit cells 171u that are the same or different from unit cells 171u forming the array of unit cells 171 on the primary portion 170p of the front surface 170f of the corresponding grid reflector 170. [000314] Referring to FIG.43A, the first grid reflector 170 ₁ , the one in front of the other, can include a plurality of laterally spaced apart cutouts 1201, shown as two aligned with two columns or linear arrays of radiating elements 222, that correspond to a position of a feed stalk 222f of a corresponding radiating element 222. The cutouts 1201 may have a larger size than any (interior) aperture 172 of a unit cell 171u or even larger than a single unit cell 171u. [000315] Turning now to FIGS. 44A-44B, a plurality of (more than two) stacked grid reflectors 170 may be used. As shown, there are four stacked grid reflectors 170 ₁ -170 ₄ , but three or greater than four grid reflectors 170 may be used. [000316] Referring to FIGS.44C-44E, different configurations of the left and right sides 170s of a respective set of grid reflectors 170 including at least first and second grid reflectors 170 ₁ , 170 ₂ are shown. [000317] FIG. 44C shows the front/first grid reflector 170 ₁ with the side wall 170w’ having the oblique angle but with the second grid reflector 170 ₂ having a straight side segment 170s that is parallel to/coplanar with the main surface 170p thereof. The reverse orientation of the different side wall configurations may also be used. [000318] FIG. 44D shows the front/first grid reflector 170 ₁ with the side wall 170w’ having the oblique angle but with the second grid reflector 170 ₂ having a side wall 170w’ that is forwardly and rearwardly perpendicular to the primary portion 170p of the forwardly facing surface 170f. The reverse orientation of the different side wall configurations may be used. Attorney Docket No.9833.6700.WO [000319] FIG.44E is similar to FIG.44D, but the second grid reflector 170 ₂ has a side wall 170w’ that is rearwardly perpendicular to the primary portion 170p of the forwardly facing surface 170f. The reverse orientation of the different side wall configurations may also be used. [000320] Referring to FIGs.45-49, each of the first and second grid reflectors 170 ₁ , 170 ₂ can an array of unit cells 171. The first array 171 ₁ of unit cells 171 can have a different pattern/configuration that the second array 171 ₂ of unit cells 171. [000321] The first grid reflector 170 ₁ can define a band pass filter for one or more defined frequency bands and optionally a reflector for at least one other frequency band. The second grid reflector 170 ₂ can define a band pass filter for one or more defined frequency bands and a band stop filter for one or more different defined frequency bands. [000322] In some embodiments, the first grid reflector 170 ₁ can define a band pass filter for a first frequency band corresponding to the high band radiating elements 1195 and the second grid reflector 170 ₂ can define a band pass filter for the first frequency band and a band stop filter for the low band radiating elements 222 and/or the mid-band radiating elements 232 which may widen the operating bandwidth. [000323] The first and second grid reflectors 170 ₁ , 170 ₂ can be configured with respective arrays of unit cells 171 that cooperate to improve cross-polarization performance and may improve the rejection of the middle band. The array of unit cells 171 of the different grid reflectors 170 ₁ , 170 ₂ can be configured so that a rejection frequency band of the middle band may be close to the frequency pass band of the high band radiating elements 1195. [000324] Referring to FIGS. 45-47, the first and second arrays of unit cells 171 can have an open aperture(s) and can have an open center interior 172 devoid of metal and each unit cell 171u can include a metal or metallized perimeter 173. The first and second grid reflectors 170 ₁ , 170 ₂ can each have an array of unit cells 171. Each unit cell 171u can be defined by a metal perimeter 173 surrounding a shaped aperture or apertures 172. The aperture(s) 172 of a respective unit cell 171u of the second grid reflector 170 ₂ can have a greater surface area of the aperture or apertures 172 of the unit cell 171u of the first grid reflector 170 ₁ . A center aperture 172c of at least some of the aligned unit cells 171u of the first and second grid reflectors 170 ₁ , 170 ₂ can be aligned to define a continuous forward through space therebetween and toward a front radome 100f/111 (FIG.42) of the base station antenna 100. [000325] Referring to FIGS. 45-47, 48A and 48B, the combination of first and second grid layers can provide respective different grid reflector unit cell configurations/arrangements: (1) band pass and band pass; (2) band stop and band stop; (3) band pass and band stop; (4) high Attorney Docket No.9833.6700.WO band pass and band stop. The combination of first, second and third grid layers 170 ₁ , 170 ₂ , 170 ₃ can provide (high) band pass (with low band reflection) at the first grid 170 ₁ , a mid-band band stop at the second grid 170 ₂ and a mid-band band stop at the third grid 170 ₃ with both the second and third grids, 170 ₂ , 170 ₃ , also providing high band pass. The benefits of the multiples of the stacked grid reflectors 170 ₁ , 170 ₂ and 170 ₃ (two or more such stacked grid reflectors) with respective different configurations of arrays 171 of unit cells 171u providing the different filtering performance(s) can provide a desired (wider) pass band and one or more desired stop bands/band stops. [000326] Referring to FIG. 48B, three stacked (in a front to back direction) grid layers 170 ₁ , 170 ₂ , 170 ₃ may be used. The first grid 170 ₁ can be provided as a band pass grid configured to pass RF signal in a high band frequency from high band radiating elements 1195 behind the first grid 170 ₁ , optionally provided by the active antenna module 110 (FIG. 51A, for example) and block or reflect low band frequency from low band radiating elements 222. The second and third grids 170 ₂ , 170 ₃ can each be provided as band stop grids configured to pass RF signals in the high band frequency but block and/or reflect signal from mid band radiating elements 232. [000327] The second and third grids 170 ₂ , 170 ₃ can each be configured with the stop band centered at a common frequency of the mid-band frequency range. The mid-band frequency range can be a 1.7 GHz- 2.7 GHz frequency range. [000328] The second and third grids 170 ₂ , 170 ₃ can each be configured to have stop bands centered (the term “centered” referring to the frequency at which maximum rejection occurs within the band stop frequency range) at different, offset frequencies of the mid-band frequency band. For example, the stop band for the second grid 170 ₂ can be centered at a first portion of the mid-band frequency range and the stop band for the third grid 170 ₃ can be centered at a second portion of the mid-band frequency. The stop band for the third grid 170 ₃ can be centered at a higher frequency than the stop band for the second grid 170 ₂ . The stop band for the second grid 170 ₂ can be centered at a lower end portion of the mid-band frequency range and the stop band for the third grid 170 ₃ can be centered at a higher end portion of the mid-band frequency range. The mid-band frequency can comprise frequencies in the 1.7 GHz- 2.7 GHz frequency range. [000329] The second grid 170 ₂ can be configured to provide a band stop filter with a band stop frequency band in a range of 1.7-2.7 GHz and having a first frequency at maximum rejection in a lower half of the band stop frequency band and the third grid 170 ₃ can be configured to provide a band stop filter with a band stop frequency band in a range of 1.7-2.7 Attorney Docket No.9833.6700.WO GHz and having a second frequency at maximum rejection in a higher half of the band stop frequency band. [000330] The second grid 170 ₂ can provide a band stop filter with a band stop frequency band in a range of 1.7-2.7 GHz and the third grid 170 ₃ can provide a band stop filter with a band stop frequency band in a range of 1.7-2.7 GHz. A frequency at maximum rejection for the band stop filters of the second and third grids 170 ₂ ,170 ₃ can each be substantially the same (+/-15%) and can be within 2 GHz to 2.25 GHz. [000331] Referring to FIG. 48A, the base station antenna 100 can include at least one matching layer 300 as discussed above. The base station antenna 100 can include support posts 310 as also discussed above. [000332] FIG.48A also shows that a rearmost grid reflector 170 ₃ can reside adjacent or on an interior surface of a rear wall 100r of the passive antenna housing 100h. The second grid reflector 170 ₂ can be replaced or used with the rearmost grid reflector 170 ₃ . [000333] The primary portions 170p of each of the plurality of grid reflectors 170 can be parallel to the primary surface 214p of the primary reflector 214. The front/first grid reflector 170 ₁ can have a primary portion 170p that can be co-planar with the primary surface 214p of the primary reflector 214 (FIG. 50) with the other of the plurality of the grid reflectors 170 behind the primary reflector 214. In other embodiments, all of the plurality of grid reflectors 170 can have a primary portion 170p grid reflector 170 can reside behind a primary surface of the primary reflector 214 in a different plane and longitudinally offset therefrom. [000334] Turning now to FIGS.49 and 50, the base station antenna (shown without the radome 111) comprises the passive antenna assembly 190 and primary reflector 214 discussed above with respect to other embodiments. The base station antenna 100 can comprise a plurality of linear arrays 220 (shown as two) of low band radiating elements 222 and a plurality of linear arrays 230 (shown as four) of mid-band radiating elements 232 that extend in front of the at least one grid reflector 170 with the side wall 170w’ that projects forwardly. The first and second grid reflectors 170 ₁ , 170 ₂ can reside at an upper end portion 100u of the base station antenna 100. The right and left sides 170s can project forward to provided angled forward side “wing” segments 170wa defining right and left three-dimensional side walls 170w’, and one or both of the first and second reflectors 170 ₁ , 170 ₂ (where two or more such grid reflectors 170 are used) can include unit cells 171u on those side walls 170w’. A plurality of longitudinally spaced apart and laterally extending cross-struts 1250 can be coupled to the right and left side walls 170s for structural stability. Attorney Docket No.9833.6700.WO [000335] Turning now to FIGS. 51A, 51B and 52-54, an upper portion 100u of a base station antenna 100 comprises the first and second grid reflectors 170 ₁ , 170 ₂ which reside behind at least some of the low band radiating elements 222. One feed stalk 222f of one of the radiating elements 222 can extend rearward align with the cutouts 1201 provided in the first/front grid reflector 170 ₁ (see, FIG.43A, 54) and can couple to a feed board 1200’. [000336] FIGS.51A, 52 and 53 illustrate some or all of that the feed boards 1200’ for the low band radiating elements 222 can have feed networks 1210 positioned on a front primary surface of the first grid 1701. The feed networks 1210 can have a plurality of linear signal trace segments 1211 comprising metal in orthogonal traces, vertical and horizontal segments as shown, extending between open spaces 1214. The linear signal trace segments 1211 can be in-line with metal or metallized segments of respective unit cells 171u so as to not block or reside over open interior spaces 172 (FIG.46) of unit cells 171u of the first and/or the second grid reflector reflectors 170 ₁ , 170 ₂ . One or more of the feed boards 1200’ can be arranged behind the first grid reflector 170 ₁ and one or more of the feed boards 1200’ can be arranged in front of the first grid reflector 170 ₁ . [000337] In some embodiments, feed boards 1200’ of radiating elements, such as low band 222 and/or mid-band 232 radiating elements, can be arranged so that some reside on a first (front primary surface) and some reside on a second (rear primary surface) of that grid reflector 170 ₁ . [000338] Turning now to FIGS. 51B and 51C, the first grid 170 ₁ behind low band radiating elements 222 and mid band radiating elements 232 and with first feed board networks 1210 ₁ for the low band radiating elements 222 provided on a front surface of the first grid 170 ₁ . FIG.51C is a rear view of the first grid 170 ₁ shown in FIG.51B showing second feed board networks 1210 ₂ for the mid-band radiating elements 232 on a rear surface of the first grid 170 ₁ according to embodiments of the present invention. Feed stalks 232f of the mid-band radiating elements 232 can extend through apertures in the first grid 170 ₁ to couple to the second feed board network 1210 ₂ . One or more feed boards 1200 of one or more mid-band radiating element 232 can be coupled to the feed stalks 232 and the second feed network 1210 ₂ . The feed networks 12102 can have the plurality of linear signal trace segments 1211 comprising metal in orthogonal traces, vertical and horizontal segments as shown, extending between open spaces 1214 as discussed for the first feed networks 1210 (FIG.51A). [000339] As shown in FIGS. 48A, 48B and 51B, for example, the low band radiating elements 222 can project forward a greater distance than the mid band radiating elements 232. Attorney Docket No.9833.6700.WO [000340] Turning now to FIGS. 54A and 54B, the base station antenna 100 can be configured to provide a first grid reflector 170 ₁ and a second grid layer and/or reflector 170 ₂ inside a housing 100h of the passive antenna. The active antenna unit 110 can reside adjacent and behind the housing 100h. The first grid reflector 170 ₁ can be attached to a pair of longitudinally extending rails 1218. The second grid layer and/or reflector 170 ₂ can reside behind the rear end of the rails 1218. [000341] FIGS. 55A and 55B illustrate that the second grid reflector 170 ₂ can reside inside a chamber 1228 that extends in a front-to-back direction of the base station antenna 100 and that is defined by the right and left rails 1218 and the first grid reflector 170 ₁ . Thus, the second grid layer or reflector 170 ₂ can reside in front of the rear end 1218e of each of the rails 1218. The second grid layer and/or reflector 170 ₂ can reside closer to the first grid reflector 170 ₁ than the rear end 1218e of the rails 1218. Placement of the second grid layer and/or reflector 170 ₂ to be nested in the chamber 1228 may reduce performance influence from the rails 1218. [000342] Turning now to FIG.56, a grid reflector 170 can be coupled to the right and left side rails 1218 and the unit cells 171u can extend a full lateral extent of the grid reflector 170, or at least a distance that is over/in front of the rails 1218. The rails 1218 can be non-electrically conductive and may comprise fiberglass and/or plastic (e.g., polymer, copolymer materials). [000343] FIG. 57 illustrates a rail system 1238 which provides a frame 1218f that comprises the two side rails 1218 and a top 1218t that couples the side rails 1218. The plurality of laterally extending struts 1250 can be coupled to the side rails 1218. The rail system 1238 can also connect the primary reflector 214 to the grid reflector 170. The rail system 1238 can be non-electrically conductive and may comprise fiberglass and/or plastic (e.g., polymer, copolymer materials). [000344] Turning now to FIGS. 58 and 59, where two, three or more even more grid layers are used, shown as three grid layers, 170 ₁ , 170 ₂ , 170 _3, each grid layer 170 ₁ , 170 ₂ , 170 ₃ can have a different size and/or shape from another grid so that one or more of the grid layers 170 ₁ , 170 ₂ , 170 ₃ extends partially along or across the base station antenna 100. The three grid layers 170 ₁ , 170 ₂ , 170 ₃ can reside at a top portion 100t of the base station antenna 100. The first grid layer 170 ₁ can merge at a bottom portion into the primary reflector 214. [000345] The first grid layer 170 ₁ can have a greater longitudinal and lateral extent than the second grid layer 170 ₂ and the third grid layer 170 ₃ . As shown in FIG.58, the second and third grid layers 170 ₂ , 170 ₃ reside behind the first grid layer 170 ₁ and only across a lower portion (lower 20%-50%) of the first grid layer 170 ₁ , behind mid-band radiating elements 232 Attorney Docket No.9833.6700.WO (low band radiating elements are not shown but can be provided to project forward of the first grid layer 170 ₁ and the primary reflector 214, similar to the example base station antennas in other figures herein as will be understood by one of skill in the art). Thus, there can be three stacked grid layers 170 ₁ , 170 ₂ , 170 ₃ at only this portion of the base station antenna 100. [000346] FIG. 59 shows the second and third grid layers 170 ₂ , 170 ₃ at laterally spaced apart left and right segments of the base station antenna 100, behind the first grid layer 170 ₁ . The second and third grid layers 170 ₂ , 170 ₃ can be provided as respective laterally spaced apart segments positioned at left and right segments of the base station antenna, behind the first grid reflector 170 ₁ . [000347] The triple grid layers 170 ₁ , 170 ₂ , 170 ₃ in the base station antenna 100 can cooperate to provide a wide band rejection for low and/or mid-band radiating elements while allowing RF signal from high band radiating elements to pass through. [000348] The first grid layer 170 ₁ can be provided as a patterned sheet metal layer and the second and third grid layers 170 ₂ , 170 ₃ can be provided as printed circuit boards, spaced apart in the front to back direction of the base station antenna 100. While preferred in some embodiments, it is noted that the first grid layer 170 ₁ is not required to be sheet metal or to have the right and left sides provided in an oblique angle. [000349] Embodiments of the present invention have been described above with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. [000350] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items. [000351] It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to Attorney Docket No.9833.6700.WO the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (i.e., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.) [000352] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer or region to another element, layer or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. [000353] The term “about” used with respect to a number refers to a variation of +/- 10%. [000354] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" "comprising," "includes" and/or "including" when used herein, specify the presence of stated features, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and/or groups thereof. [000355] Aspects and elements of all of the embodiments disclosed above can be combined in any way and/or combination with aspects or elements of other embodiments to provide a plurality of additional embodiments.