WITH DISTRIBUTED BALUN

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit and priority of U.S. Provisional Patent Application

No. 62/436,992, titled "Millimeter- Wave Spiral Antenna with Distributed Balun" and filed on

December 20, 2016, the entire contents of which are hereby incoiporated by reference herein.

BACKGROUND

[0002] 1. Field

[0003] The present disclosure generally relates to antenna units that include a spiral antenna and a balun to transfer a balanced signal from the spiral antenna to an unbalanced signal on a coaxial pin (i.e., a coaxial center conductor).

[0004] 2. Description of the Related Art

[0005] Spiral antennas may include two spiral conductors positioned on a substrate. The two spiral conductors may receive a signal from the atmosphere, and the signal may be referred to as a balanced signal because the signal is balanced across the two spiral conductors. However, in various situations, it may be desirable for the signal to be transmitted as an unbalanced signal, such as when it is desirable for the signal to be transmitted via a coaxial cable. In that regard, a balun may be utilized to convert the balanced signal to the unbalanced signal, and vice versa.

[0006] Conventional baluns have a relatively narrow bandwidth, thus restricting the bandwidth of the antenna unit. Similarly, conventional baluns may be relatively bulky, resulting in a corresponding antenna unit having an undesirably large size. Likewise, conventional baluns may be relatively complex, resulting in the corresponding antenna unit having a relatively large cost increase due to the inclusion of the balun. [0007] Accordingly, systems and methods for creating spiral antenna units with a relatively small and inexpensive balun with a relatively large bandwidth are desirable.

SUMMARY

[0008] Disclosed herein is an antenna unit. The antenna unit includes a spiral antenna having a first contact point and a second contact point. The antenna unit further includes a coaxial pin designed to be electrically connected to the first contact point of the spiral antenna. The antenna unit further includes a coaxial outer layer having a tubular shape, at least partially surrounding the coaxial pin, and having a coaxial taper towards a coaxial end proximate to the spiral antenna, the coaxial end being designed to be electrically connected to the second contact point of the spiral antenna, and the coaxial taper functioning as a balun to transfer a balanced signal from the spiral antenna to an unbalanced signal on the coaxial pin.

[0009] Also disclosed is an antenna unit. The antenna unit includes a spiral antenna having a substrate, a first spiral conductor located on the substrate and having a first contact point, and a second spiral conductor located on the substrate and having a second contact point. The antenna unit further includes a coaxial pin designed to be electrically connected to the first contact point of the spiral antenna. The antenna unit further includes a coaxial outer layer having a tubular shape, at least partially surrounding the coaxial pin, and having a coaxial taper towards a coaxial end proximate to the spiral antenna and designed to be electrically connected to the second contact point of the spiral antenna, the coaxial taper functioning as a balun to transfer a balanced signal from the spiral antenna to an unbalanced signal on the coaxial pin.

[0010] Also disclosed is an antenna unit. The antenna unit includes a spiral antenna having a disk shape, a first contact point, and a second contact point. The antenna unit further includes an absorber being aligned with the spiral antenna about a central axis, spaced from the spiral antenna by an air gap, and defining an opening along the central axis through a length of the absorber. The antenna unit further includes a housing defining a cavity for receiving the absorber and being aligned with the spiral antenna and the absorber along the central axis. The antenna unit further includes a coaxial outer layer having a tubular shape, extending through the opening of the absorber, and having a coaxial taper towards a coaxial end proximate to the spiral antenna, the coaxial end being designed to be electrically connected to the second contact point of the spiral antenna. The antenna unit further includes a coaxial pin extending through the coaxial outer layer and being designed to be electrically connected to the first contact point of the spiral antenna. The antenna unit further includes a dielectric material located between the coaxial outer layer and the coaxial pin and having a dielectric taper towards the spiral antenna.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Other systems, methods, features, and advantages of the present invention will be or will become apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. Component parts shown in the drawings are not necessarily to scale, and may be exaggerated to better illustrate the important features of the present invention. In the drawings, like reference numerals designate like parts throughout the different views, wherein:

[0012] FIG. 1 is a drawing illustrating an exploded view of an antenna unit having a distributed balun according to an embodiment of the present disclosure;

[0013] FIG. 2 is a cross-sectional view of the antenna unit of FIG. 1 according to an embodiment of the present disclosure;

[0014] FIG. 3 is an enlarged view of a radially inner portion of a spiral antenna of the antenna unit of FIG. 1 according to an embodiment of the present disclosure; [0015] FIG. 4 is an enlarged view of a coaxial outer conductor of the antenna unit of FIG. 1 having a nib or nub according to an embodiment of the present disclosure;

[0016] FIG. 5 is an enlarged cross-sectional view of a portion of the antenna unit of FIG. 1 illustrating features of the distributed balun according to an embodiment of the present disclosure;

[0017] FIG. 6 is a side view of the antenna unit of FIG. 1 and illustrates various dimensions of the antenna unit according to an embodiment of the present disclosure;

[0018] FIG. 7 is a cross-sectional view illustrating an antenna unit having a single contiguous conductor that operates as a housing and a coaxial connector according to an embodiment of the present disclosure;

[0019] FIG. 8 is a flowchart illustrating a method for forming an antenna unit similar to the antenna unit of FIG. 1 or the antenna unit of FIG. 7 according to an embodiment of the present disclosure;

[0020] FIG. 9 is a graph illustrating results of a simulation using a model of the antenna unit of FIG. 1 according to an embodiment of the present disclosure; and

[0021] FIG. 10 is a graph illustrating results of simulations using a model of the antenna unit of FIG. 1 according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0022] Described herein are systems and methods for creating antenna units with a distributed balun. In particular, the balun is formed by tapering (i.e., forming an angular cut in) a coaxial outer layer and a dielectric such that they taper towards a spiral antenna. The coaxial outer layer and a coaxial pin are electrically connected to the spiral antenna. The balun provides a desirable transfer of the balanced signal from the spiral antenna to an unbalanced signal that propagates along the coaxial pin.

[0023] The systems and methods provided herein provide significant advantages over conventional antenna units. For example, the balun of the antenna units provides a relatively large bandwidth that is significantly greater than conventional baluns. Furthermore, the antenna units described herein provide an increased gain of a desirable mode of a received or transmitted signal relative to an undesirable mode of the received or transmitted signal. Additionally, the antenna units described herein provide a relatively flat again over a relatively large bandwidth, which is likewise desirable. Also, the balun structure provided herein is relatively simple to form and thus less expensive than conventional balun structures. The balun structure is also relatively small, allowing the antenna unit to have a relatively small size.

[0024] Referring to FIGS. 1 and 2, an antenna unit 100 is designed to receive and transmit wireless signals, such as signals in a radio frequency (RF) band. The antenna unit 100 includes a housing 102, an absorber layer 104, a spiral antenna 106, an absorber ring 108, and a coaxial connector 1 10. Each of these elements may be assembled such that they are aligned along a central axis 122, which may also be referred to as a longitudinal axis of the antenna unit 100.

[0025] The housing 102 defines a conical backshort 1 12. The conical backshort 1 12 converges towards the spiral antenna 106. Stated differently, the conical backshort 1 12 converges towards an apex that is nearer to the spiral antenna 106 than any other portion of the conical backshort 112.

[0026] The housing 102 may further define a coaxial outer layer 1 14. The coaxial outer layer 114 may function as an outer conductor of a coaxial connector or transmission line. The coaxial outer layer 1 14 may have a tubular shape. In that regard, the conical backshort 1 12 (or the housing 102) may define a backshort channel 214, such that a dielectric material 124 and a coaxial pin 126 are received by the coaxial outer layer 1 14 and the backshort channel 214. The backshort channel 214 may be a chamiel or other passageway through which the dielectric material 124 and the coaxial pin 126 are positioned or located, and the material of the conical backshort 1 12 (such as the material near the backshort channel 214) may function as an outer conductor of the coaxial connector (i.e., may function as an extension of the coaxial outer layer 1 14). The coaxial outer layer 114, the coaxial pin 126, and the dielectric material 124 may together function as a coaxial comiector or transmission line. In that regard, the dielectric material 124 may be located radially outward from the coaxial pin 126, and the coaxial outer layer 1 14 may be located radially outward from the dielectric material 124.

[0027] The housing 102 may further include an outer ring 1 13 that defines a cavity 1 15. The cavity 1 15 may function to receive the absorber layer 104, and the outer ring 1 13 may provide a structure to which the spiral antenna 106 may be coupled.

[0028] In some embodiments, the housing 102 including the conical backshort 1 12, the coaxial outer layer 1 14, and the outer ring 1 13 may include a single contiguous conductor. In some embodiments, one or more of these components (such as the coaxial outer layer 1 14 or the outer ring 1 13) may be a separate component and be bonded to the remaining components, such as via welding. However, providing these components as a single contiguous conductor may result in a reduced total cost of manufacture of the antenna unit 100.

[0029] The coaxial outer layer 1 14 may have a thickness 222. The thickness 222 may be between 1 thousandths of an inch (1 mil, 0.025 millimeters (mm)) and 30 mils (0.76 mm), between 5 mils (0.13 mm) and 20 mils (0.51 mm), or about 9 mils (0.23 mm). Where used in this context, about refers to the stated value plus or minus 10 percent of the stated value. [0030] The material of any one or more of the housing 102, the conical backshort 1 12, the coaxial outer layer 1 14, the outer ring 1 13, and the coaxial pin 126 may include any conductive material, such as a metal including brass, copper, tin, aluminum, gold, silver, or the like. Aluminum may be especially desirable due to its relatively high conductivity and relatively low weight.

[0031] In some embodiments, all outer surfaces of the housing 102, the conical backshort 112, the coaxial outer layer 1 14, the outer ring 1 13, and the coaxial pin 126 may be gold plated. Gold plating may be advantageous because it provides a surface that is relatively unlikely to corrode and has relatively high conductivity relative to most other materials.

[0032] The dielectric material 124 may include any dielectric material such as ceramic, mica, glass, plastic, a metal oxide, polytetrafluoroethylene (PTFE), or the like. In some embodiments, PTFE may be a preferred material due to its relatively low dielectric constant and its relative suppleness (resulting in a low likelihood of the dielectric material 124 breaking in response to stress).

[0033] The absorber layer 104 is designed to fit within the cavity 1 15 defined by the outer ring 1 13 of the housing 102. In that regard, the absorber layer 104 may define a conical cavity 202 that is designed to receive the conical backshort 1 12, such that the surfaces of the absorber layer 104 and the conical backshort 1 12 that face each other remain in constant contact. In some embodiments, the absorber layer 104 may be bonded with at least one of the conical backshort 1 12 or the outer ring 1 13. In some embodiments, the absorber layer 104 may be press-fit into the conical cavity 202 such that the absorber layer 104 remains in place relative to the housing 102 due to friction between the absorber layer 104 and the outer ring 1 13. [0034] The absorber layer 104 may include any material capable of absorbing RF signals. The absorber layer 104 may include a magnetic absorber, a foam absorber, or the like. For example, the absorber layer 104 may include carbon bonded together with a bonding material (such as rubber or epoxy), may include polyurethane (or other) foam impregnated with a dielectric material, may include a foam loaded with a carbon-based dielectric, may include magnetic fillers to achieve permeability at certain frequencies, or the like. In some embodiments, the absorber layer 104 may include a material referred to as Eccosorb ^® MF-124, available from Taird of London, United Kingdom.

[0035] Referring briefly to FIGS. 1 , 2, and 3, the spiral antenna 106 may include a substrate 1 16, a first spiral conductor 1 18, and a second spiral conductor 120. The substrate 1 16 may include any nonconductive material or other material with relatively low conductive properties such as, for example, a laminate, alumina, quartz, PTFE, epoxy, glass fibers, paper, a ceramic, or the like. In some embodiments, the substrate 1 16 may include a filled PTFE (random glass or ceramic) composite laminate available as RT/duroid ^® from Rogers Corporation of Rogers, CT. In some embodiments, RT/duroid ^® may be a preferred material due to having a relatively high tensile strength and yield strength, along with a relatively low coefficient of thermal expansion, thus resulting in greater durability than many other substrate options.

[0036] The first spiral conductor 1 18 and the second spiral conductor 120 may include any conductive material. For example, the spiral conductors 1 18, 120 may include copper, silver, gold, or the like. In some embodiments, the substrate 1 16 may be plated with or bonded to copper (or another metal or conductor), which may then be plated with gold and etched to form the first spiral conductor 1 18 and the second spiral conductor 120. In some embodiments, the gold plating may occur after the etching. [0037] The spiral antenna 106 may have an antenna thickness 220. The antenna thickness 220 may be, for example, between 1 mil (0.025 mm) and 20 mils (0.51 mm), between 2 mils (0.051 mm) and 10 mils (0.25 mm), or about 5 mils (0.13 mm).

[0038] The spiral antenna 106 may be coupled to the housing 102. The spiral antenna 106 may be coupled or bonded to the outer ring 1 13 and may be located at least one of within the cavity 1 15 or outside of the cavity 1 15. For example, spiral antenna 106 may be bonded to the outer ring 1 13 via a bonding agent, such as epoxy, or connected to the outer ring 1 13 via a press- fit connection within the cavity 1 15.

[0039] Returning reference to FIGS. 1 and 2, the spiral antenna 106 may be coupled to the outer ring 1 13 in such a way as to form an air gap 200 between the absorber layer 104 and the spiral antenna 106. The air gap 200 may have a gap thickness 212 that may be between 5 mils (0.13 mm) and 75 mils (1.9 mm), between 10 mils (0.25 mm) and 50 mils (1.3 mm), or about 31 mils (0.79 mm).

[0040] The absorber ring 108 may have a ring, or annular, shape, and may thus be referred to as an annular absorber ring 108. The absorber ring 108 may be located radially outward from the first spiral conductor 1 18 and the second spiral conductor 120. In that regard, the absorber ring 108 may fail to contact the first spiral conductor 1 18 and the second spiral conductor 120. In some embodiments, the absorber ring 108 may be coupled or bonded to the substrate 1 16 of the spiral antenna 106 or to the outer ring 1 13 of the housing 102 such as, for example, via a bonding agent such as epoxy.

[0041] As best seen in FIG. 2, the absorber ring 108 may taper radially inward. In that regard, the absorber ring 108 may have a trapezoidal cross section. The absorber ring 108 may have a first thickness 208 at a radially outward end and a second thickness 210 at a radially inward end. The first thickness 208 may be greater than the second thickness 210, thus providing the radially inward taper of the absorber ring 108. In some embodiments, the first thickness 208 may be between 2 mils (0.051 mm) and 20 mils (0.51 mm), between 3 mils (0.076 mm) and 15 mils (0.38 mm), or about 10 mils (0.25 mm). In some embodiments, the second thickness 210 may be between 0.5 mils (0.013 mm) and 10 mils (0.25 mm), between 1 mil (0.025 mm) and 8 mils (0.2 mm), or about 5 mils (0.13 mm).

[0042] The absorber ring 108 may include any material capable of absorbing RF signals. The absorber ring 108 may include a magnetic absorber, a foam absorber, or the like. For example, the absorber ring 108 may include carbon bonded together with a bonding material (such as rubber or epoxy), may include polyurethane (or other) foam impregnated with a dielectric material, may include a foam loaded with a carbon-based dielectric, may include magnetic fillers to achieve permeability at certain frequencies, or the like. In some embodiments, the absorber ring 108 may include a material referred to as Eccosorb ^® MF-124, available from Laird of London, United Kingdom.

[0043] The coaxial connector 1 10 may define or include a sheath portion 216 and a pin opening 218. The sheath portion 216 may be electrically coupled to the housing 102 and, thus, to the coaxial outer layer 1 14. In that regard, the sheath portion 216 may function as an outer conductor of a coaxial connector or transmission line. The coaxial pin 126 may extend through the pin opening 218 and may be separated from the sheath portion 216 by a dielectric material or an insulator. In that regard, the coaxial pin 126 may operate as an inner conductor of a coaxial connector or transmission line. Thus, the signal received by the spiral antenna 106 may be transmitted along the coaxial pin 126 and received by a coaxial cable that is coupled to the sheath portion 216 of the coaxial connector 110 and to the coaxial pin 126. [0044] The housing 102 may include a flange 204 at a radially outer end thereof. The flange 204 may define bolt apertures 206 for receiving bolts or other fasteners 207. The bolts or other fasteners 207 may be used to couple the housing 102 to the coaxial connector 1 10. The flange 204 may be outwardly-tapered to reduce the amount of material used in the housing 102, thus reducing the weight of the housing 102. Stated differently, the flange 204 may taper towards the spiral antenna 106.

[0045] In operation, the spiral antenna 106 may receive a wireless signal from the atmosphere. The spiral antenna 106 may be designed to receive a signal within a band that is defined between a low-frequency and a high-frequency. The antenna unit may be optimized based on a desired band.

[0046] The absorber ring 108 may reduce the likelihood of interference at an outer ring of each of the spiral conductors 1 18, 120. The outer rings of the spiral conductors 1 18, 120 may correspond to the low- frequency end of the band such that the absorber ring 108 reduces the likelihood of interference at the low-frequency end of the band.

[0047] The signal received by the spiral antenna 106 may include a right-hand circularly polarized (CP) mode received from a direction orthogonal to a front of the spiral antenna 106 (as shown by an arrow 130), and a left-hand circularly polarized mode received from the same direction. It may be undesirable for the spiral antenna 106 to receive the right-hand CP mode as the right-hand CP mode may cause interference with the left-hand CP mode, thus reducing clarity of the received signal. In that regard, the absorber layer 104 may absorb or reject a portion of the right-hand mode, while allowing the spiral antenna 106 to receive the left-hand mode. The air gap 200 may likewise reject a portion of the right-hand mode. The gap thickness 212 may be selected in such a way as to achieve a desirable trade-off between effect on the right- hand mode and rejection of the left-hand mode.

[0048] The conical backshort 1 12 may operate as a focusing element to focus one of the CP modes towards the spiral antenna 106. The conical shape of the conical backshort 1 12 is due to the following analysis:

[0049] As described above, the radially outward end of the spiral antenna 106 corresponds to the low-frequency end of the band. Thus, the radially inward end of the spiral antenna 106 corresponds to the high-frequency end of the band. In that regard, it is desirable to have a greater distance between the spiral antenna 106 and the conical backshort 1 12 at the radially outward end of the spiral antenna 106 (because of the lower frequency (i.e., greater wavelength) received at this location), and to have a smaller distance between the spiral antenna 106 and the conical backshort 1 12 at the radially inward end of the spiral antenna 106 (due to the shorter wavelength at this location).

[0050] Referring briefly to FIGS. 2, 3, 4, and 5 the coaxial outer layer 1 14 may have a coaxial end 400 designed to be electrically coupled to the spiral antenna 106 at a first contact point 300 of the first spiral conductor 1 18. In that regard, the coaxial end 400 may define a nib or nub 402 that extends through an opening in the spiral antenna 106 (such as through the substrate 1 16). The nib or nub may be electrically coupled to the first contact point 300 such as, for example, via a first wire bond or ribbon bond 500.

[0051] The coaxial pin 126 may include a pin end 514 designed to be electrically coupled to the spiral antenna 106 at a second contact point 302. For example, the pin end 514 may extend through an opening in the spiral antenna 106 (such as through the substrate 1 16) and be electrically coupled to the second contact point 302 such as, for example, via a second wire bond or ribbon bond 502.

[0052] As shown, the first contact point 300 and the second contact point 302 are shown being located at the radially inner ends of the first and second spiral conductors 1 18, 120, respectively. In some embodiments, the first contact point 300 and the second contact point 302 may be located at radially outer ends of the first and second spiral conductors 1 18, 120, respectively.

[0053] The signal traveling through the spiral conductors 1 18, 120 of the spiral antenna 106 may be referred to as a balanced signal as it is split or divided among two balanced conductors (the spiral conductors 1 18, 120). However, the signal that exits the antenna unit 100 is transported along the coaxial pin 126 (with the coaxial outer layer 1 14 being connected to a ground) and may thus an unbalanced signal. A special type of transformer, referred to as a balun, may be utilized to convert the balanced signal from the spiral antenna 106 to the unbalanced signal on the coaxial pin 126.

[0054] Referring to FIGS. 2 and 5, a combination of features may function as the balun for converting the balanced signal from the spiral antenna 106 to the unbalanced signal on the coaxial pin 126. In particular, the coaxial outer layer 1 14 may be tapered towards the coaxial end 400. Stated differently, the coaxial outer layer 1 14 may have a coaxial taper 506 which may form a part of the balun. The coaxial taper 506 may extend from the coaxial end 400 to a location within at least one of the air gap 200 or the absorber layer 104. The coaxial taper 506 may form an angle with the central axis 122 that is greater than 0 degrees and less than 90 degrees. For example, the angle may be between 10 degrees and 80 degrees, between 30 degrees and 60 degrees, or between 35 degrees and 55 degrees. [0055] The dielectric material 124 may likewise be tapered towards the spiral antenna 106. Stated differently, the dielectric material 124 may have a dielectric taper 508 that forms a part of the balun. The dielectric material 124 may or may not contact the spiral antenna 106. In that regard, the dielectric taper 508 may extend through some or all of the air gap 200, and may extend through a portion of the absorber layer 104. In that regard, the absorber layer 104 defines an opening 516 through which the coaxial outer layer 1 14 and the dielectric material 124 may extend. The dielectric taper 508 may form an angle with the central axis 122 that is greater than zero degrees and less than 90 degrees. For example, the angle may be between 10 degrees and 80 degrees, between 30 degrees and 60 degrees, or between 35 degrees and 55 degrees.

[0056] The dielectric taper 508 may match the coaxial taper 506. Stated differently, the dielectric taper 508 may be aligned with the coaxial taper 506. In that regard, the angle formed by the dielectric taper 508 may match the angle formed by the coaxial taper 506, and the combination of the dielectric taper 508 and the coaxial taper 506 may form a flat planar surface.

[0057] As the signal is transmitted from the spiral antenna 106 to the coaxial pin 126 and the coaxial outer layer 1 14, the dielectric taper 508 and the coaxial taper 506 may effectively operate as a balun to transfer the signal from the spiral antenna 106 to the coaxial pin 126.

[0058] Referring to FIG. 6, the antenna unit may have specific dimensions. In particular, the spiral antenna 106 may have a radius 600 that is between 0.1 inches (2.54 mm) and 1 inch (25.4 mm), between 0.2 inches (5.1 mm) and 0.6 inches (15 mm), or about 0.4 inches (10 mm).

[0059] The housing 102 may have a housing length 602 that is between 0.05 inches (1.3 mm) and 0.5 inches (13 mm), between 0.15 inches (3.8 mm) and 0.4 inches (10 mm), or about 0.247 inches (6.274 mm). [0060] The housing 102 may likewise have a housing diameter 604. The housing diameter 604 may be between 0.1 inches (2.54 mm) and 1 inch (25 mm), between 0.4 inches (10 mm) and 0.8 inches (20 mm), or about 0.6 inches (15 mm).

[0061] The entire antenna unit 100 may have a unit length 606. The unit length 606 may be between 0.1 inches (2.54 mm) and 1 inch (25 mm), between 0.3 inches (7.6 mm) and 0.8 inches (20 mm), or about 0.567 inches (14.40 mm).

[0062] Returning reference to FIGS. 1 and 2, the antenna unit 100 may be designed for use with existing coaxial connectors 110. In that regard, the housing 102, the absorber layer 104, the spiral antenna 106, and the absorber ring may be manufactured or otherwise formed. The coaxial outer layer 1 14 may be cut or otherwise formed to have the coaxial taper illustrated as the coaxial taper 506 of FIG. 5. The dielectric material 124 may be formed or cut to have the dielectric taper illustrated as the dielectric taper 508 of FIG. 5. The coaxial pin 126 and the coaxial connector 1 10 may be purchased or otherwise obtained, and the components may then be assembled or coupled together.

[0063] Referring now to FIG. 7, another antenna unit 700 may be similar to the antenna unit 100 of FIG. 1. In that regard, the antenna unit 700 may include a housing 702, an absorber layer 704, a spiral antenna 706, an absorber ring 708, a coaxial outer layer 714, a dielectric material 724, and a coaxial pin 726 that may be oriented and function in a similar manner as the corresponding components of the antenna unit 100 of FIG. 1. The antenna unit 700 may include a single continuous conductor 703 that includes the features of the housing 102 and the coaxial connector 1 10 of the antenna unit 100 of FIG. 1. In that regard, the housing 702 may define a pin opening 718 that extends through a length of the housing 702, and may further define a sheath portion 716. It may be desirable to manufacture the antenna unit 700 (as opposed to the antenna unit 100 of FIG. 1) if a relatively large quantity of units are to be manufactured, as the cost of the antenna unit 700 may decrease below the cost of manufacturing the antenna unit 100 of FIG. 1 as the quantity ordered increases.

[0064] Referring now to FIG. 8, a method 800 for forming an antenna unit having a distributed balun that includes a tapered coaxial outer layer and a tapered dielectric material is shown. In block 802, a housing may be provided that includes a conical backshort and defines a cavity and a coaxial outer layer. For example, the housing may be formed using any known techniques such as additive manufacturing, testing, forging, or the like. In some embodiments, the housing may further include features of a coaxial connector.

[0065] In block 804, a dielectric material (which may have a tubular shape) may be inserted through the center of the coaxial outer layer.

[0066] In block 806, a cut may be formed in the coaxial outer layer and the dielectric material such that they each taper towards the spiral antenna (i.e., a forward end of the antenna unit). In some embodiments, the cut in the coaxial outer layer may be formed during block 802.

[0067] In block 808, a coaxial pin may be placed through the dielectric tube (and thus through the coaxial outer layer).

[0068] In block 810, an absorber layer may be placed in the cavity. The absorber layer may be coupled to the housing via a bonding material or via a press or interference fit.

[0069] In block 812, a spiral antenna maybe coupled to the housing (such as at an outer ring of the housing). The spiral antenna maybe coupled to the housing in such a way as to form an air gap between the absorber layer and the spiral antenna. [0070] In block 814, an absorber ring may be coupled to the spiral antenna such that it is located radially outward from spiral conductors of the spiral antenna. The absorber ring may be formed to taper radially inward and to have a trapezoidal cross section.

[0071] In block 816, the coaxial outer layer may be connected to a first contact point of the spiral antenna, and the coaxial pin may be coupled to a second contact point of the spiral antenna. For example, these couplings may be performed using a wire bond, a ribbon bond, or any other electronic coupling techniques, such as forming a solder joint between the electronic components.

[0072] In block 818, the assembly that has been manufactured up to this point may be connected electrically and mechanically to a coaxial connector. In some embodiments, when the housing is formed to further include a coaxial connector, block 818 may not be performed.

[0073] Referring now to FIGS. 1 and 9, simulations were performed using a model of the antenna unit 100. In particular, FIG. 9 illustrates a graph 900 that plots a desirable mode 902 and an undesirable mode 904 for the antenna unit 100. The results show a relatively wide frequency range with relatively flat gain in one circular polarization (i.e., the desirable mode 902, left hand circular polarization) and good rejection of the other polarization (i.e., the undesirable mode 904, right hand circular polarization). The antenna gain for the left hand circular polarization, LHCP (i.e., the desirable mode 902), is about 5 dB and the gain for the right hand circular polarization, RHCP (i.e., the undesirable mode 904), is suppressed 15-25 dB below the LHCP over a bandwidth of 30-100 GHz. These results illustrate desirable results.

[0074] Referring to FIGS. 1 and 10, additional simulations were performed using the model of the antenna unit 100, and the results are illustrated in a graph 1000. As shown in the graph 1000, the beam width is relatively flat over the operating bandwidth, and nearly equal across the two cardinal cuts of Phi=0 and 90 degrees, both desirable properties of the antenna unit 100.

[0075] Where used throughout the specification and the claims, "at least one of A or B" includes "A" only, "B" only, or "A and B." Exemplary embodiments of the methods/systems have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent wan-anted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted, except in light of the appended claims and their equivalents.