FIELD

[0001] The present disclosure relates to communications systems and, in particular, to resonators that are usable, for example, with radio frequency ("RF") filters.

BACKGROUND

[0002] Base station antennas for wireless communications systems are used to provide cellular communications service to fixed and mobile users that are within defined coverage areas of the respective base station antennas. These base station antennas typically include one or more linear arrays or two-dimensional arrays of radiating elements, such as dipole, or crossed- dipole, radiating elements that act as individual antenna elements. Each of these arrays may be connected to one or more RF ports. The RF ports are used to pass RF signals between the arrays and one or more radios.

[0003] Example base station antennas are discussed in International Publication No. WO 2017/165512 to Bisiules, U.S. Patent Application No. 15/921,694 to Bisiules et al., and U.S. Patent Application No. 63/024,846 to Hamdy et al., the disclosures of which are hereby incorporated herein by reference in their entireties. Many cellular base stations include RF filters that are mounted within a base station antenna or on an antenna tower adjacent the base station antenna. As an example, a cellular base station may include (i) a base station antenna having one or more arrays of radiating elements, (ii) a radio that is coupled to the array(s), and (iii) one or more RF filters that are coupled between the radio and the array(s). For example, the RF filter(s) may be part of an RF feed network for the array(s).

SUMMARY

[0004] An RF device, according to embodiments of the present invention, may include a housing that includes a floor and a plurality of sidewalls that protrude upward from the floor. The RF device may include a slotted resonator that is inside the housing. The slotted resonator may have a plurality of slots therein and a bottom surface that faces the floor of the housing. Moreover, a portion of the bottom surface of the slotted resonator may be separated from the floor of the housing by air.

[0005] In some embodiments, the portion of the bottom surface of the slotted resonator may be a first portion, and the RF device may include an insulating spacer that is between the floor of the housing and a second portion of the bottom surface of the slotted resonator. Moreover, a diameter of the slotted resonator may be at least 20 millimeters ("mm"). A diameter of the insulating spacer may be no more than half the diameter of the slotted resonator, or no more than three-quarters of the diameter of the slotted resonator.

[0006] According to some embodiments, the slots may include four slots or six slots. Moreover, the RF device may include a tuning screw having a portion that is inside an opening of the slotted resonator. A first and a second of the slots may be opposite each other, with the tuning screw therebetween. The housing and the slotted resonator may be a metal housing and a ceramic slotted transverse magnetic ("TM") mode resonator, respectively.

[0007] In some embodiments, the bottom surface of the slotted resonator may not contact any metal.

[0008] An RF device, according to some embodiments, may include a housing having a cavity therein. The RF device may include a resonator that is inside the cavity. Moreover, the RF device may include an insulating spacer that is between a bottom surface of the resonator and a floor of the housing. The insulating spacer may be narrower than the resonator.

[0009] In some embodiments, the resonator may be a slotted resonator having a plurality of slots therein. Moreover, the bottom surface of the resonator may be free of any metal plating thereon and/or free of any solder thereon.

[0010] According to some embodiments, a diameter of the resonator may be 20-34 mm. Moreover, a diameter of the insulating spacer may be no more than three-quarters of the diameter of the resonator.

[0011] An RF device, according to some embodiments, may include a housing. Moreover, the RF device may include a TM mode slotted resonator that has a plurality of slots therein and that is suspended above a floor of the housing.

[0012] In some embodiments, each of the slots may extend from a bottom surface of the TM mode slotted resonator to a top surface of the TM mode slotted resonator. Moreover, the RF device may include an insulating spacer that is between the bottom surface of the TM mode slotted resonator and the floor of the housing, and the insulating spacer may be narrower than the TM mode slotted resonator.

[0013] According to some embodiments, the RF device may include a cover on the housing. The cover may be opposite and spaced apart from the top surface of the TM mode slotted resonator. Moreover, each of the slots may have a length that is more than one-third, and less than one-half, of a diameter of the TM mode slotted resonator.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 A is a top perspective view of a conventional RF filter device having a cavity resonator.

[0015] FIG. IB is a side perspective view of the cavity resonator of FIG. 1A.

[0016] FIG. 1C is a section perspective view of the cavity resonator of FIG. 1 A.

[0017] FIG. 2A is a top view of an RF device having a cavity resonator, according to embodiments of the present invention.

[0018] FIG. 2B is a cross-sectional view of the RF device of FIG. 2A.

[0019] FIG. 2C is a top perspective view of the cavity resonator of FIG. 2A and the spacer of FIG. 2B arranged side-by-side outside of the cavity of FIG. 2 A.

[0020] FIG. 2D is a section perspective view of the cavity resonator of FIG. 2A.

[0021] FIGS. 2E-2G are perspective views showing top and side surfaces of different slotted examples of the cavity resonator of FIG. 2 A.

DETAILED DESCRIPTION

[0022] Pursuant to embodiments of the present invention, RF devices are provided that include a suspended cavity resonator. As used herein, the term "suspended" refers to a resonator that is spaced apart from a floor of an RF device housing by an insulating spacer and/or by air. A suspended resonator thus may not contact the floor or a metal pedestal that is between the floor and the suspended resonator. Rather, the metal pedestal may be omitted from the RF device.

[0023] FIG. 1 A is a top perspective view of a conventional RF filter device 100 having a ceramic TM mode cavity resonator 120, the bottom surface of which contacts metal. Such a resonator operates with a TM cavity mode. For example, the bottom surface of the resonator 120 may contact a metal pedestal 170 (FIG. IB), which is a structural support that may be fixed to a floor 110F of a metal housing 110 of the device 100. The metal (e.g., stainless steel, aluminum, brass, etc.) of the pedestal 170 may have a thermal expansion factor similar to that of a ceramic material of the resonator 120, and may be used to short the resonator 120 to the housing 110.

[0024] A plurality of interior sidewalls 110S of the housing 110 protrude upward from the floor 110F, thereby defining a cavity 130 in which the resonator 120 is configured to operate. The housing 110 is configured to receive a cover 140 (e.g., a metal cover) that faces a top surface of the resonator 120 and covers the cavity 130. The metal cover 140 includes an opening that receives a tuning screw 160 that can extend into an opening of the resonator 120. Moreover, an RF filter provided by the resonator 120 is coupled between a first RF port 151 and a second RF port 152. The ports 151, 152 may comprise connectors that are attached to exterior sidewalls of the housing 110. For example, the port 151 may be coupled to a radio, and the port 152 may be coupled to one or more arrays of radiating elements of a cellular base station antenna.

[0025] FIG. IB is a side perspective view of the cavity resonator 120 of FIG. 1A. As shown in FIG. IB, the metal pedestal 170 is on the bottom surface of the resonator 120. For simplicity of illustration, a three-dimensional shape of the cavity 130 is shown translucently in FIG. IB, without showing the housing 110 (FIG. 1 A) that defines the cavity 130. FIG. IB also shows that a diameter of the pedestal 170 is wider than a diameter of the resonator 120. As an example, the diameter of the resonator 120 may be 19 mm or smaller, and the dimensions of the cavity 130 may be 36 mm (length) by 36 mm (width) by 23 mm (height). Dimensions of the cavity 130 and the resonator 120 may be selected to provide optimal performance at fundamental TM mode. If the height of the cavity 130 were instead increased beyond 23 mm, then frequencies of spurious modes of the resonator 120 may be too close to fundamental TM mode. Moreover, the cavity 130 may be cylindrical rather than cube-shaped and may have a diameter of 36 mm.

[0026] FIG. 1C is a section perspective view of the cavity resonator 120 of FIG. 1A. As shown in FIG. 1C, a tuning screw 160 can be inserted into an opening of the resonator 120. The tuning screw 160 may be a metal tuning screw or a dielectric tuning screw. For simplicity of illustration, the cover 140 (FIG. 1 A) and the housing 110 (FIG. 1 A) are omitted from view in FIG. 1C. [0027] Ideally, the resonator 120 and the floor 110F (FIG. 1 A) of the housing 110 would be connected by a perfect conductor. The unloaded quality factor (or Qo factor) of the fundamental mode, which establishes an upper limit for RF performance, of the resonator 120 may thus depend on the quality and purity of metal-ceramic connection between the pedestal 170 and the resonator 120.

[0028] To improve the metal-ceramic connection between the resonator 120 and the pedestal 170, the bottom surface of the resonator 120 may be metal-plated (e.g., silver-plated) and soldered to the top surface of the pedestal 170, which may also be metal-plated (e.g., silver- plated). A process of metal-plating and soldering the bottom surface of the resonator 120, however, may be delicate. As an example, the connection between the bottom surface of the resonator 120 and the pedestal 170 may suffer from solder-joint cracking and/or other physical imperfections. Moreover, the solder joint may result in passive intermodulation ("PIM") distortion.

[0029] According to the present invention, however, a resonator can be suspended in a metal housing such that the resonator does not have a metal connection to a floor of the housing. The suspended resonator thus may be free of any metal plating thereon and free of any solder thereon, thereby reducing/eliminating problems resulting from the delicate process for metalplating and soldering the bottom surface of the conventional resonator 120 (FIGS. 1A-1C). Moreover, RF performance of the suspended resonator may be enhanced by including a plurality of slots in the suspended resonator and/or by increasing a diameter of the suspended resonator relative to a diameter of the conventional resonator 120.

[0030] Example embodiments of the present invention will be described in greater detail with reference to the attached figures.

[0031] FIG. 2A is a top view of an RF device 200 having a cavity resonator 220, according to embodiments of the present invention. The device 200 may be implemented as, for example, an RF filter device that is configured to provide an RF filtering response. As shown in FIG. 2 A, a housing 110 of the device 200 may, in some embodiments, have a cube shape. As an example, a cavity 130 inside the housing 110 may have dimensions of 36 mm in an X direction, 36 mm in a Y direction, and 23 mm in a Z direction. In other embodiments, the cavity 130 may have a cylindrical shape, which may have, for example, a 36 mm diameter. Moreover, the resonator 220 may have a much wider diameter than the conventional resonator 120 of FIG. 1 A, even though the resonators 220, 120 can be in respective cavities 130 that have the same (or similar) dimensions.

[0032] For simplicity of illustrating the resonator 220 and the cavity 130 in FIG. 2A, a cover 140 of the device 200 is shown side-by-side with the housing 110 rather than on top of the housing 110. For further simplicity of illustration, RF ports/connectors (e.g., ports 151, 152 (FIG. 1 A)) are omitted from view in FIG. 2 A. In some embodiments, the cover 140 and the housing 110 may be a metal cover and a metal housing, respectively. Moreover, the cover 140 may have an opening 140H through which a tuning screw 160 (FIG. 2B) may extend downward into an opening 220H (FIG. 2C) of the resonator 220. The tuning screw 160 may be a metal tuning screw or a dielectric tuning screw, and the resonator 220 may be a ceramic resonator. As an example, a ceramic material of the resonator 220 may be KM02.

[0033] FIG. 2B is a cross-sectional view of the RF device 200 of FIG. 2A. For simplicity of illustration, the cover 140 (FIG. 2A) is omitted from view in FIG. 2B. As shown in FIG. 2B, first and second interior sidewalls 110S-1, 11 OS-2 of the housing 110 protrude upward, in the Z direction, from the floor 110F of the housing 110. The sidewalls 110S-1, 11 OS-2 are opposite each other in the X direction. The sidewalls 110S-1 , 110S-2 and the floor 110F collectively define the cavity 130 in which the resonator 220 is configured to operate.

[0034] FIG. 2B shows that a spacer 250 is between the resonator 220 and the floor 110F. In some embodiments, the spacer 250 may be implemented as an insulating (and thus non-metal) spacer. As a result, the resonator 220 is not connected to the floor 11 OF by metal. For example, the spacer 250 may implemented as a plastic (e.g., polytetrafluoroethylene ("PTFE")), or other dielectric, spacer.

[0035] Moreover, the spacer 250 may be narrower, in the X and Y directions, than the resonator 220. As an example, a diameter DI of the resonator 220 may be at least 20 mm (e.g., 20-34 mm), and a diameter D2 of the spacer 250 may be no more than half, or no more than three-quarters, of the diameter DI. As a result, a bottom surface 220B of the resonator 220 that faces the floor 110F may have a first portion Pl that is separated from the floor 11 OF by a gap GZ (e.g., an air gap) and a second portion P2 that is separated from the floor 11 OF by the spacer 250. In some embodiments, the second portion P2 may be an inner/center portion of the bottom surface 220B, and the first portion Pl may be an outer portion of the bottom surface 220B that surrounds/encircles the second portion P2. For example, an opening 220H (FIG. 2C) in a center of the resonator 220 may be coaxial with an opening 250H (FIG. 2C) in a center of the spacer 250. The tuning screw 160 can extend into the opening 220H. For simplicity of illustration, the openings 220H, 250H are omitted from view in FIG. 2B, though it will be understood that the tuning screw 160 that is shown in FIG. 2B corresponds to an upper portion of the opening 220H.

[0036] A side surface 220S of the resonator 220 may be spaced apart from an adjacent interior surface 110S of the housing 110 by a gap GX, which may be a distance (e.g., 1-1.5 mm) equal or similar to that of the gap GZ. Moreover, a top surface 220T of the resonator 220 that is opposite (e.g., that faces) a bottom surface of the cover 140 may be spaced apart from the bottom surface of the cover 140 by a distance (e.g., 1-1.5 mm) equal or similar to that of the gap GZ.

[0037] FIG. 2C is a top perspective view of the cavity resonator 220 of FIG. 2A and the spacer 250 of FIG. 2B arranged side-by-side outside of the cavity 130 of FIG. 2A. As shown in FIG. 2C, the opening 220H of the resonator 220 may have a larger diameter than the opening 250H of the spacer 250. The opening 220H is configured to receive the tuning screw 160 (FIG. 2B), and the opening 250H may be configured to receive a screw (e.g., a silver-plated screw) that attaches the spacer 250 to the floor 110F (FIG. 2B) of the housing 110 (FIG. 2B). Accordingly, the screw that attaches the spacer 250 to the floor 110F may, in some embodiments, have a narrower diameter than the tuning screw 160. Though the opening 220H may extend from the top surface 220T of the resonator 220 to the bottom surface 220B (FIG. 2B) of the resonator 220, the tuning screw 160 does not necessarily extend to a level of the bottom surface 220B, and thus may not contact the spacer 250. Rather, the bottom surface of the tuning screw 160 may, in some embodiments, be positioned at a depth inside the opening 220H that is below a level of the top surface 220T and above the level of the bottom surface 220B.

[0038] FIG. 2D is a section perspective view of the cavity resonator 220 of FIG. 2A. As shown in FIG. 2D, an upper portion of the tuning screw 160 may be above a level of the top surface 220T of the resonator 220, as the tuning screw 160 may protrude downward from the opening 140H (FIG. 2 A) of the cover 140 (FIG. 2 A) and extend into the opening 220H (FIG. 2C) of the resonator 220. The top surface 220T may be spaced apart from the cover 140 by air. For simplicity of illustration, the cover 140 is omitted from view in FIG. 2D.

[0039] FIG. 2D also illustrates that the first portion Pl of the bottom surface 220B of the resonator 220 is exposed to air by the spacer 250, which is on (e.g., in contact with) the second portion P2 of the bottom surface 220B but not on the first portion Pl . The first portion Pl is thus separated from the floor 110F (FIG. 2B) of the housing 110 (FIG. 2B) by air rather than by a solid material. As a result, the resonator 220 may have a higher Qo factor than it would if the spacer 250 covered the entire bottom surface 220B. Moreover, the bottom surface 220B does not contact any metal.

[0040] FIGS. 2E-2G are perspective views showing top and side surfaces of different slotted examples of the cavity resonator 220 of FIG. 2 A. As shown in FIG. 2E, the resonator 220 may be implemented as a slotted resonator SR having six slots S-l through S-6 therein. Moreover, FIG. 2E illustrates that the cavity 130 may, in some embodiments, be cylindrical rather than cube-shaped. For example, the cavity 130 may have a diameter of 45 mm and a height of 30 mm. The slotted resonator SR, however, is not limited to being in either a cylindrical cavity 130 or a cube-shaped cavity 130. Nor is the slotted resonator SR limited to having six slots S. Instead, the slotted resonator SR may have, for example, two or four slots S.

[0041] Each slot S may, in some embodiments, extend from a bottom surface 220B (FIG. 2B) of the slotted resonator SR to a top surface 220T of the slotted resonator SR. The slots S may thus divide the slotted resonator SR into six regions R-l through R-6. For example, the first slot S-l may separate the first region R-l from the sixth region R-6, the second slot S-2 may separate the first region R-l from the second region R-2, the third slot S-3 may separate the second region R-2 from the third region R-3, the fourth slot S-4 may separate the third region R- 3 from the fourth region R-4, the fifth slot S-5 may separate the fourth region R-4 from the fifth region R-5, and the sixth slot S-6 may separate the fifth region R-5 from the sixth region R-6. In some embodiments, each slot S may extend a first length LI from a side surface 220S of the slotted resonator SR to an opening 220H of the slotted resonator SR. Accordingly, the first length LI may be equal to (i) the radius of the slotted resonator SR minus (ii) the radius of the opening 220H. Moreover, pairs of the slots S may be opposite each other, with the opening 220H therebetween. As an example, the first slot S-l may be opposite the fourth slot S-4, with the tuning screw 160 (FIG. 2B) that is in the opening 220H therebetween.

[0042] As shown in FIG. 2F, a slotted resonator SR' may have six slots S-l through S-6 therein that extend a second length L2 from a side surface 220S of the slotted resonator SR' to a point of the slotted resonator SR' that is between the side surface 220S and an opening 220H (FIG. 2C) of the slotted resonator SR'. Accordingly, the second length L2 may be shorter than the first length LI (FIG. 2E). In some embodiments, the lengths LI, L2 may each be more than one-third, and less than one-half, of a diameter DI (FIG. 2B) of the slotted resonator SR'. Moreover, the cavity 130 may have dimensions of, for example, 36 mm (length) by 36 mm (width) by 20.5 mm (height).

[0043] As shown in FIG. 2G, a slotted resonator SR" may have as few as two slots S-l, S-2 therein. For example, the first slot S-l may be opposite the second slot S-2, with the tuning screw 160 therebetween. The slots S-l, S-2 are between first and second regions R-l, R-2 of the slotted resonator SR".

[0044] The slotted resonator SR" having two slots S therein may have improved spurious mode separation relative to a resonator 220 that has no slots S therein, without penalizing the Qo factor. Increasing the number of slots S from two to four can provide additional spurious mode separation. Moreover, increasing the number of slots S from four to six (e.g., as shown in the slotted resonator SR (FIG. 2E) or the slotted resonator SR' (FIG. 2F)) can provide even more spurious mode separation. Expanding the number of slots S beyond six, however, may penalize the Qo factor without significantly improving spurious mode separation.

[0045] A resonator 220, having either a plurality of slots S therein or no slots S therein, may be implemented as a TM mode resonator according to some embodiments. Accordingly, the TM mode may be the fundamental (resonant rather than spurious) mode of the resonator 220. The TM mode resonator may be used instead of a transverse electromagnetic ("TEM") mode resonator, which may have lower Qo than the TM mode resonator. As used herein, the term "spurious mode separation" refers to separation between spurious mode and fundamental mode frequencies of the resonator 220.

[0046] To ensure the best RF performance of the resonator 220, a ratio of the spurious mode frequency to the fundamental mode frequency may need to be greater than one. For example, the ratio may be greater than 1.1, greater than 1.2, greater than 1.3, or greater than 1.4 when the resonator 220 comprises a plurality of slots S therein. The ratio may generally increase with increasing frequency when the resonator 220 operates in a range (e.g., a resonant-frequency range) between 1,600 megahertz ("MHz") and 2,400 MHz, and may generally increase when increasing the number of slots S from two to four or from four to six. The Qo factor may also generally increase with increasing frequency in that range. Operating in the lower half of that range, however, may require the resonator 220 to have a relatively large diameter DI (FIG. 2B). As an example, to operate at a resonant frequency that is between 1,600 MHz and 1,900 MHz (e.g., at 1,800 or 1,900 MHz), the diameter DI may need to be between 20 mm and 34 mm (e.g., 30-34 mm).

[0047] RF performance of the resonator 220 may also be affected by the tuning screw 160. For example, deeper penetration of the tuning screw 160 into the opening 220H (FIG. 2C) of the resonator 220 may decrease the Qo factor of the resonator 220. Moreover, increasing the length of the tuning screw 160 can decrease spurious mode separation. When the resonator 220 has a plurality of slots S therein, however, the Qo factor may still be much higher (e.g., 25-30% higher) than that of the conventional resonator 120 (FIG. 1 A), as may spurious mode separation. In some embodiments, good RF performance (e.g., high Qo factor and/or spurious mode separation) may be achieved by the resonator 220 while using a wider range of tuning screw 160 depths relative to the conventional resonator 120, as the resonator 220 may be less sensitive than the conventional resonator 120 to the tuning screw 160. The resonator 220 may also provide stable RF performance over a wider temperature range than the conventional resonator 120, and thus may be better suited for temperature changes.

[0048] Though a single RF device 200 having a single cavity resonator 220 is illustrated in FIG. 2 A, a base station antenna may, in some embodiments, be coupled to a plurality of RF devices 200 having respective cavity resonators 220 and/or to an RF device 200 that includes a plurality of cavities 130 having respective cavity resonators 220 therein. Moreover, an RF device 200 may, in some embodiments, be integrated into a cellular base station antenna, such as in a feed network thereof. In other embodiments, the RF device 200 may be external to the antenna. For example, the RF device 200 may be mounted on a base station antenna tower. As an example, a standalone unit that is coupled between a radio and the antenna may comprise the RF device 200.

[0049] In some embodiments, the RF device 200 may be implemented as a diplexer that is usable with a base station antenna. Diplexers are three-port networks that are used to split incoming electrical signals input at a common port onto two frequency-selective ports, and to combine electrical signals received at the two frequency-selective ports (which are often referred to as a low-frequency port and a high-frequency port) and to output the combined signal through the common port. The RF device 200 is not limited, however, to diplexers. Rather, the RF device 200 may, in some embodiments, be implemented as a non-diplexer RF filter that is usable with a base station antenna. [0050] RF devices 200 (FIG. 2A) having a suspended cavity resonator 220 (FIGS. 2A- 2G) according to embodiments of the present invention may provide a number of advantages. These advantages include requiring neither metallization nor soldering for the resonator 220, which may, in some embodiments, be a TM mode resonator. By contrast, a conventional TM mode resonator 120 (FIG. 1 A) may require silver-plating and soldering to short the resonator 120 to a floor 110F (FIG. 1 A) of a housing 110 (FIG. 1 A). Instead, the resonator 220 is spaced apart from the floor 11 OF by a spacer 250 (FIG. 2B) and/or by air, and thus may limit/prevent physical malfunctions and/or PIM distortion associated with metallization and soldering. In some embodiments, the resonator 220 may have lower sensitivity than the conventional resonator 120 to a tuning screw 160 (FIG. 2B).

[0051] Moreover, assembly of the TM mode resonator 220 inside the housing 110 may be mechanically (e.g., structurally) similar to assembly of a transverse electric ("TE") mode resonator, despite the resonator 220 being configured to operate in the TM mode rather than the TE mode. Assembly of the resonator 220 may thus be relatively simple to implement.

[0052] Further advantages include achieving a low resonant frequency and a high Qo factor by implementing the resonator 220 with a plurality of slots S (FIGS. 2E-2G) and/or a wide diameter DI (FIG. 2B). For example, the Qo factor of the resonator 220 may be at least 25% higher than that of the conventional resonator 120 when using the same cavity 130 size. Moreover, the slots S may block the TE mode, as they may be perpendicular to an electric field of the TE mode. When the resonator 220 is implemented with six slots S, separation between fundamental and spurious mode frequencies may be significantly higher relative to the conventional resonator 120. As an example, a ratio of the spurious mode frequency to the fundamental mode frequency for the resonator 220 may be 1.4 or higher when the resonator 220 is implemented with six slots S.

[0053] The present invention has been described above with reference to the accompanying drawings. The present invention is not limited to the illustrated embodiments. Rather, these embodiments are intended to fully and completely disclose the present invention to those skilled in this art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.

[0054] Spatially relative terms, such as "under," "below," "lower," "over," "upper," "top," "bottom," and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features. Thus, the example term "under" can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0055] Herein, the terms "attached," "connected," "interconnected," "contacting," "mounted," "coupled," and the like can mean either direct or indirect attachment or coupling between elements, unless stated otherwise.

[0056] Well-known functions or constructions may not be described in detail for brevity and/or clarity. As used herein the expression "and/or" includes any and all combinations of one or more of the associated listed items.

[0057] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present 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 in this specification, 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.