# Patent

## Title
Ultra wide band antenna element

## Abstract

Antenna unit cells suitable for use in antenna arrays are disclosed, as are antenna arrays and mounting platform such as an aircraft comprising antenna unit cells. In one embodiment, an antenna unit cell comprises a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, a feed pin coupled to at least one of the first plurality of radiating elements, and a shorting pin coupled to each of the first plurality of radiating elements and to a ground plane. Other embodiments may be described.

## Background
RELATED APPLICATIONS
This application is a continuation-in-part of commonly assigned U.S. patent application Ser. No. 13/278,841 to Manry, et al, filed Oct. 21, 2011 and of U.S. patent application Ser. No. 13/115,944 to Manry, et al, filed May 25, 2011, entitled Ultra Wide Band Antenna Element, the disclosures of which are incorporated herein by reference in their respective entirety.


BACKGROUND
The subject matter described herein relates to electronic communication and sensor systems and specifically to configurations for antenna arrays for use in such systems.
Microwave antennas may be constructed in a variety of configurations for various applications, such as satellite reception, remote sensing or military communication. Printed circuit antennas generally provide antenna structures which are low-cost, lightweight, low-profile and relatively easy to mass produce. Such antennas may be designed in arrays and used for radio frequency systems such as identification of friend/foe (IFF) systems, electronic warfare systems, signals intelligence systems, personal communication service (PCS) systems, satellite communication systems, etc.
Recently, interest has developed in ultra-wide bandwidth (UWB) arrays for use in communication and sensor systems. Thus there is a need for a lightweight phased array antenna with a wide frequency bandwidth and a wide angular scan range and that is conformally mountable to a platform surface.
SUMMARY
In one embodiment, an antenna unit cell a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, a feed pin coupled to at least one of the first plurality of radiating elements, and a shorting pin coupled to each of the first plurality of radiating elements and to a ground plane.
In another embodiment, an antenna array comprising a plurality of unit cells wherein at least a subset of the unit cells comprises a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, a feed pin coupled to at least one of the first plurality of radiating elements, and a shorting pin coupled to each of the first plurality of radiating elements and to a ground plane.
In another embodiment, an aircraft comprises a communication system and an antenna assembly coupled to the communication system and comprising a plurality of unit cells. At least a subset of the unit cells comprises a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, a feed pin coupled to at least one of the first plurality of radiating elements, and a shorting pin coupled to each of the first plurality of radiating elements and to a ground plane.
In another embodiment, a method to make an antenna assembly comprises printing a first plurality of radiating elements on a first surface of a substrate, wherein the first plurality of radiating elements are arranged in groups of opposing pairs that form opposing dipoles disposed about a central point and printing a second plurality of radiating elements on a second surface, opposite the first surface, of the substrate. In some embodiments the second plurality of radiating elements are rectangular in shape and arranged to form opposing dipoles disposed about the central point, and the first plurality of radiating elements partially overlap the second plurality of radiating elements.
In another embodiment, a method to use an antenna assembly comprises providing an antenna array comprising a plurality of unit cells, at least a subset of the unit cells comprising a dielectric substrate having a length extending along a first axis and a width extending along a second axis, a first plurality of radiating elements disposed on a first side of the dielectric substrate, and a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side. In some embodiments the first plurality of radiating elements extend to an edge of the unit cell and the second plurality of radiating elements overlap portions of the first plurality of radiating elements. The method further comprises coupling one or more feed pins to the first plurality of radiating elements and to a signal source for transmission.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure



BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of methods and systems in accordance with the teachings of the present disclosure are described in detail below with reference to the following drawings.
FIG. 1 is a schematic top-view of an antenna unit cell, according to embodiments.
FIG. 2 is a schematic side elevation view of the antenna unit cell depicted in FIG. 1.
FIG. 3 is a schematic top, plan view of an antenna array formed from a plurality of unit cells, according to embodiments.
FIG. 4 is a schematic side elevation view of the antenna array depicted in FIG. 3.
FIG. 5 is a schematic top, plan view of a printed antenna array, according to embodiments.
FIG. 6 is a schematic bottom, plan view of a printed antenna array, according to embodiments.
FIG. 7 is a schematic side elevation view illustration of an antenna assembly, according to embodiments.
FIG. 8 is a schematic illustration of an aircraft-based communication, radar, or other RF sensor system which may incorporate an antenna, according to embodiments.
FIG. 9 is a schematic top-view of an antenna unit cell, according to embodiments.
FIG. 10 is a schematic side elevation view of the antenna unit cell depicted in FIG. 9.
FIG. 11 is a schematic top, plan view of an antenna array formed from a plurality of unit cells, according to embodiments.
FIG. 12 is a schematic side elevation view of the antenna array depicted in FIG. 9.
FIG. 13 is a schematic top, plan view of a printed antenna array, according to embodiments.
FIG. 14 is a schematic bottom, plan view of a printed antenna array, according to embodiments.
FIG. 15 is a schematic, top-view of an antenna unit cell, according to embodiments.
FIGS. 16A and 16B are schematic side elevation view of the antenna unit cell depicted in FIG. 15.
FIG. 17 is a schematic top, plan view of an antenna array formed from a plurality of unit cells, according to embodiments.
FIG. 18 is a schematic side elevation view of the antenna array depicted in FIG. 17.



DETAILED DESCRIPTION
Configurations for antenna unit cells suitable for use in array antenna systems, and antenna systems incorporating such unit cells are described herein. Specific details of certain embodiments are set forth in the following description and the associated figures to provide a thorough understanding of such embodiments. One skilled in the art will understand, however, that alternate embodiments may be practiced without several of the details described in the following description.
The invention may be described herein in terms of functional and/or logical block components and various processing steps. For the sake of brevity, conventional techniques related to electronic warfare, radar, signal intelligence systems, data transmission, signaling, network control, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical embodiment.
The following description may refer to components or features being “connected” or “coupled” or “bonded” together. As used herein, unless expressly stated otherwise, “connected” means that one component/feature is in direct physically contact with another component/feature. Likewise, unless expressly stated otherwise, “coupled” or “bonded” means that one component/feature is directly or indirectly joined to (or directly or indirectly communicates with) another component/feature, and not necessarily directly physically connected. Thus, although the figures may depict example arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment.
FIG. 1 is a schematic top-view of an antenna unit cell, according to embodiments, and FIG. 2 is a schematic side elevation view of the antenna unit cell depicted in FIG. 1. Referring to FIGS. 1-2, in some embodiments an antenna unit cell 100 comprises a dielectric substrate 110 having a length, L, extending along a first axis 102 and a width, W, extending along a second axis 104, and a thickness, t. In some embodiments the antenna unit cell 100 is adapted to operate in a frequency range extending from about 300.0 MHz to 3.0 GHz, (i.e., a wavelength of about 100 cm to 10 cm). In such embodiments the length L and the width W measure between about 1.5 inches (38.1 mm) and 2.0 inches (50.8 mm) and the thickness, t, of the substrate measures approximately 30 mils (0.762 mm). The design scales geometrically to any 10:1 band (i.e., 2-20 GHz, 0.5-5 GHz). One skilled in the art will recognize that the particular dimensions of the antenna unit cell 100 may be a function of the design frequency as well as materials and physical configuration of the unit cell. In some embodiments the substrate 110 may be formed from a conventional substrate, e.g., a Rogers 4350 series dielectric material.
A first plurality of radiating elements 120A, 120B, 120C, 120D, which may be referred to collectively by reference numeral 120, are disposed on a first side 112 of the dielectric substrate 110. Radiating elements 120 may be coupled to a feed line 150 via one or more contacts 130A, 130B, 130C, 130D, which may be referred to collectively by reference numeral 130, such that radiating elements 120 define a feed network. In some embodiments the contacts 130 extend through vias 118 formed in the substrate 110. In some embodiments the contacts 130 may be formed integrally with the radiating elements, while in other embodiments the contacts 130 may be formed separately and electrically coupled to the radiating elements. In some embodiments the first plurality of radiating elements 120 measure between about 0.5 inches and 0.7 inches in length and extend from the central feed line 150 to a point that is a distance D from the edge 116 of the unit cell. In some embodiments the distance D1 may measure between 0.13 inches (3.3 mm) and 0.18 inches (4.57 mm).
A second plurality of radiating elements 140A, 140B, 140C, 140D, which may be referred to collectively by reference numeral 140 are disposed on a second side 114 of the dielectric substrate 110. In some embodiments the second plurality of radiating elements 140 overlap portions of the first radiating elements 140, such that the second plurality of radiating elements 140 may be capacitively coupled to the first plurality of radiating elements 120 that define the feed network. In some embodiments the first plurality of radiating elements 120 measure between about 0.5 inches and 0.8 inches in length and extend from the edge 116 of the unit cell 110 to a point that is a distance D2 from the feed line 150 of the unit cell. In some embodiments the distance D2 may measure between 0.2 inches (5.08 mm) and 0.5 inches (12.7 mm).
In the embodiment depicted in FIGS. 1-2 the radiating elements 120 are substantially trapezoidal in shape and are arranged to form opposing bow-tie shaped radiating elements. The bow-tie radiating elements are oriented at ninety (90) degrees with respect to one another to provide a dual-polarization antenna structure. One skilled in the art will recognize that the radiating elements 120, 140 may be formed in various shapes and sizes.
In practice, a plurality of unit cells 110 may be positioned adjacent one another to define an antenna array. FIG. 3 is a schematic top, plan view of an antenna array formed from a plurality of unit cells, according to embodiment, and FIG. 4 is a schematic side elevation view of the antenna array depicted in FIG. 3. In the embodiment depicted in FIGS. 3-4, four antenna unit cells 100 are arranged to form a 2×2 antenna array. One skilled in the art will recognize that any number of unit cells may be combined to form an m×n antenna array.
Referring to FIGS. 3-4, in relevant part when the antenna unit cells 100 are arranged to form a 2×2 array adjacent radiating elements in the first plurality of radiating elements 120 are separated by a distance that measures twice the distance D1, i.e., 2D1. Thus, referring to FIGS. 3-4, adjacent elements 120A and 120C are separated by a distance of 2D1, as are elements 120B and 120D. By contrast, adjacent radiating elements in the second plurality of radiating elements 140 are in electrical contact with one another. Thus, as illustrated in FIGS. 3-4, radiating elements 140A, 140C are electrically connected, as are radiating elements 140B, 140D.
In some embodiments the antenna assembly may be formed by printing the respective radiating elements 120, 140 on opposing sides of a sheet of dielectric substrate. This may be illustrated with respect to FIGS. 5-6. FIG. 5 is a schematic top, plan view of a printed antenna assembly, according to embodiments, and FIG. 6 is a schematic bottom, plan view of a printed antenna assembly, according to embodiments. Referring to FIG. 5-6, a pattern of radiating elements 120 may be printed on a first surface of a substrate 110, while a pattern of radiating elements 140 may be printed on the opposing second surface of substrate 110. The resulting sheet may then be cut as desired to form an m×n array of antenna elements.
FIG. 7 is a schematic illustration of an antenna assembly 700, according to embodiments. Referring to FIG. 7, in a conformal antenna assembly the substrate layer 110 and the printed radiating layers 120, 140 may be positioned between one or more foam or dielectric layers 720 and a ground plane 710. Optionally, a cap layer 730 may be positioned over the foam layer 720. The feed pins 150 may be coupled to a signal source for transmission.
In some embodiments an aircraft-based antenna or phased array system may incorporate one or more antennas constructed according to embodiments described herein. By way of example, referring to FIG. 8, an antenna assembly 700 may be mounted on an aircraft 800, such as an airplane, helicopter, spacecraft or the like. In alternate embodiments an antenna assembly 700 may be mounted on a ground-based vehicle such as a truck, tank, train, or the like, or on a water-based vehicle such as a ship. In further embodiments an antenna 700 may be mounted on a land-based communication station.
An alternate embodiment of an antenna unit cell is described with reference to FIGS. 9-14. FIG. 9 is a schematic top-view of an antenna unit cell, according to embodiments, and FIG. 10 is a schematic side elevation view of the antenna unit cell depicted in FIG. 9. Referring to FIGS. 9-10, in some embodiments an antenna unit cell 100 comprises a dielectric substrate 110 having a length, L, extending along a first axis 102 and a width, W, extending along a second axis 104, and a thickness, t. In some embodiments the antenna unit cell 100 is adapted to operate in a frequency range extending from about 300.0 MHz to 3.0 GHz, (i.e., a wavelength of about 100 cm to 10 cm). In such embodiments the length L and the width W measure between about 1.5 inches (38.1 mm) and 2.0 inches (50.8 mm) and the thickness, t, of the substrate measures approximately 30 mils (0.762 mm). The design scales geometrically to any 10:1 band (i.e., 2-20 GHz, 0.5-5 GHz). One skilled in the art will recognize that the particular dimensions of the antenna unit cell 100 may be a function of the design frequency as well as materials and physical configuration of the unit cell. In some embodiments the substrate 110 may be formed from a conventional substrate, e.g., a Rogers 4350 series dielectric material.
A first plurality of radiating elements 120A, 120B, 120C, 120D, which may be referred to collectively by reference numeral 120, are disposed on a first side 112 of the dielectric substrate 110. A second plurality of radiating elements 140A, 140B, 140C, 140D, which may be referred to collectively by reference numeral 140 are disposed on a second side 114 of the dielectric substrate 110. Radiating elements 140 may be coupled to a feed line 150 via one or more contacts 130A, 130B, 130C, 130D, which may be referred to collectively by reference numeral 130, such that radiating elements 140 define a feed network. In some embodiments the contacts 130 may be formed integrally with the radiating elements 140, while in other embodiments the contacts 130 may be formed separately and electrically coupled to the radiating elements. In some embodiments the first plurality of radiating elements 120 measure between about 0.5 inches and 0.7 inches in length (L1) and extend from the edge 116 of the unit cell to a point between approximately 0.25 inches and 0.45 inches from the central feed line 150.
In some embodiments the second plurality of radiating elements 140 overlap portions of the first radiating elements 120, such that the first plurality of radiating elements 120 may be capacitively coupled to the second plurality of radiating elements 140 that define the feed network. In some embodiments the second plurality of radiating elements 120 measure between about 0.5 inches and 0.8 inches in length and extend the feed line connector 130 to a point to a point that is a distance D1 from the edge 116 of the unit cell 110. In some embodiments the distance D1 may measure between 0.10 inches and 0.40 inches.
In the embodiment depicted in FIGS. 9-10 the radiating elements 120 are substantially rectangular in shape and are arranged to form opposing dipoles. The radiating elements are oriented at ninety (90) degrees with respect to one another to provide a dual-polarization antenna structure. One skilled in the art will recognize that the radiating elements 120, 140 may be formed in various shapes and sizes.
In practice, a plurality of unit cells 110 may be positioned adjacent one another to define an antenna array. FIG. 11 is a schematic top, plan view of an antenna array formed from a plurality of unit cells, according to embodiment, and FIG. 12 is a schematic side elevation view of the antenna array depicted in FIG. 11. In the embodiment depicted in FIGS. 11-12, four antenna unit cells 100 are arranged to form a 2×2 antenna array. One skilled in the art will recognize that any number of unit cells may be combined to form an m×n antenna array.
Referring to FIGS. 11-12, in relevant part when the antenna unit cells 100 are arranged to form a 2×2 array adjacent radiating elements in which the second plurality of radiating elements 140 are separated by a distance that measures twice the distance D1, i.e., 2D1. Thus, referring to FIGS. 11-12, adjacent elements 140A and 140C are separated by a distance of 2D1, as are elements 140B and 140D. By contrast, adjacent radiating elements in the first plurality of radiating elements 120 are in electrical contact with one another. Thus, as illustrated in FIGS. 11-12, radiating elements 120A, 120C are electrically connected, as are radiating elements 120B, 120D.
In some embodiments the antenna assembly may be formed by printing the respective radiating elements 120, 140 on opposing sides of a sheet of dielectric substrate. This may be illustrated with respect to FIGS. 13-14. FIG. 13 is a schematic bottom, plan view of a printed antenna assembly, according to embodiments, and FIG. 14 is a schematic top, plan view of a printed antenna assembly, according to embodiments. Referring to FIG. 13-14, a pattern of radiating elements 120 may be printed on a first surface of a substrate 110, while a pattern of feed connectors 130 and radiating elements 140 may be printed on the opposing second surface of substrate 110. The resulting sheet may then be cut as desired to form an m×n array of antenna elements.
Analogous to the assembly depicted in FIG. 7, a conformal antenna assembly the substrate layer 110 and the printed radiating layers 120, 140 may be positioned between one or more foam layers 720 and a ground plane 710. Optionally, a cap layer 730 may be positioned over the foam layer 720. The feed pins 150 may be coupled to a signal source for transmission. The antenna may be mounted on an aircraft or other vehicle, as described with reference to FIG. 8.
Thus, described herein is an ultra-wide band (UWB) antenna unit cell and assembly. The antenna element may be used in the creation of wide-band arrays and/or conformal antennas that achieves ultra wide bandwidth (i.e., a 10:1 frequency band edge ratio), the ability to perform over wide scan angles, and provides both dual and separable RF polarization capability. In some embodiments the unit cell that employs a multi-layer circuit that comprises a bow-tie fan feed layer, and a layer comprising bow-tie based connected array. The circuit board may be placed over a ground plane with foam dielectric layers below and above the antenna circuit board to create the antenna element structure. A differential feed from bow-tie like fan elements is coupled capacitively to the underlying unit-cell to unit-cell connected bow-tie element layer. Such an antenna has wide applicability to communication phased antenna arrays (PAA), signal intelligence sensors and detection sensor arrays, wide band radar systems, and phased arrays used in electronic warfare.
An antenna element manufactured in accordance herewith exhibits ultra-wide bandwidth and better than 55-degree conical scan volume for the creation of conformal arrays and antennas. The design approach provides effective gain within 2 dB of the ideal gain possible for the surface area of the unit-cell for the element. The element design can be used as a wide-band antenna and/or array. The design can be scaled to any frequency band with a 10:1 ratio from the highest to the lowest frequency of desired coverage.
Another alternate embodiment of an antenna is described with reference to FIGS. 15-20 FIG. 15 is a schematic top-view of an antenna unit cell, according to embodiments, and FIGS. 16A and 16B are schematic side elevation views of the antenna unit cell depicted in FIG. 15. Referring to FIGS. 15 and 16A-16B, in some embodiments an antenna unit cell 100 comprises a dielectric substrate 110 having a length, L, extending along a first axis 102 and a width, W, extending along a second axis 104, and a thickness, t. In some embodiments the antenna unit cell 100 is adapted to operate in a frequency range extending from about 300.0 MHz to 3.0 GHz, (i.e., a wavelength of about 100 cm to 10 cm). In such embodiments the length L and the width W measure between about 1.5 inches (38.1 mm) and 2.0 inches (50.8 mm) and the thickness, t, of the substrate measures approximately 30 mils (0.762 mm). The design scales geometrically to any 10:1 band (i.e., 2-20 GHz, 0.5-5 GHz). One skilled in the art will recognize that the particular dimensions of the antenna unit cell 100 may be a function of the design frequency as well as materials and physical configuration of the unit cell. One skilled in the art will recognize that the dimensions of the antenna design may be adjusted to work over a smaller bandwidth than 10:1. In some embodiments the substrate 110 may be formed from a single or plurality of layers of a conventional substrate, e.g., a Rogers 4350 series dielectric material. In an alternate embodiment different material types and thickness of layers may be used.
A first plurality of radiating elements 120A, 120B, 120C, 120D, which may be referred to collectively by reference numeral 120, are disposed on a first side 112 of the dielectric substrate 110. A second plurality of radiating elements 140A, 140B, 140C, 140D, which may be referred to collectively by reference numeral 140 are disposed on a second side 114 of the dielectric substrate 110. Radiating elements 140 may be coupled to a feed line 150 via one or more contacts 130A, 130B, 130C, 130D, which may be referred to collectively by reference numeral 130, such that radiating elements 140 define a feed network. In some embodiments the contacts 130 may be formed integrally with the radiating elements 140, while in other embodiments the contacts 130 may be formed separately and electrically coupled to the radiating elements. In some embodiments the first plurality of radiating elements 120 measure between about 0.5 inches and 0.7 inches in length (L1) and extend from the edge 116 of the unit cell to a point between approximately 0.25 inches and 0.45 inches from a central point indicated by axis 150 on FIGS. 16A and 16B.
In some embodiments the second plurality of radiating elements 140 overlap portions of the first radiating elements 120, such that the first plurality of radiating elements 120 may be capacitively coupled to the second plurality of radiating elements. In some embodiments the second plurality of radiating elements 120 measure between about 0.5 inches and 0.8 inches in length and extend the feed line connector 130 to a point to a point that is a distance D1 from the edge 116 of the unit cell 110. In some embodiments the distance D1 may measure between 0.10 inches and 0.40 inches.
In the embodiment depicted in FIGS. 15-16 the radiating elements 120 are substantially rectangular in shape and are arranged to form opposing dipoles. The radiating elements are oriented at ninety (90) degrees with respect to one another to provide a dual-polarization antenna structure. One skilled in the art will recognize that the radiating elements 120, 140 may be formed in various shapes and sizes. By way of example, in some embodiments the radiating elements 120, 140 may be trapezoidal in shape, such as those depicted in FIGS. 1-6.
In the embodiment of the antenna unit cell depicted in FIG. 7 and 15-20 portions of the dielectric substrate 110 and layer 720 above substrate 110 are removed proximate the corners of the substrate 110 and layer 720 above substrate 110. Removing portions of the substrate 110 and layer 720 above substrate 110 proximate the corners of the substrate 110 and layer 720 above substrate 110 reduces surface wave propagation across the substrate 110 and layer 720 above substrate 110 that can cause scan-blindness in an array comprising antenna unit cell 100. One skilled in the art will recognize that removing portions of the substrate 110 and layer 720 above substrate 110 to reduce scan-blindness can be in various shapes and in a plurality of locations. In alternate embodiments different shapes and plurality locations may be used in substrate 110 than those in layer 720 above substrate 110.
In the embodiment depicted in FIGS. 15-20 the feed network is modified to remove the central feed pin 150 depicted in the embodiments described with reference to FIGS. 1-14 and replace it with a feed network that includes at least one feed pin 162 coupled to a contact 130D and one or more shorting pins 164, 165, 166 electrically coupled to each radiating element 130B. One skilled in the art will recognize that the feed pin 162 and shorting pins 164, 165, 166 may be electrically coupled directly to the radiating elements 140 or may be coupled to radiating elements 140 through an electrical connection with one or more of the contacts 130. The feed pin 162 and shorting pins 164, 165, 166 may be implemented using platted vias as commonly used in printed circuit board manufacturing. One skilled in the art will recognize that the pins can be created by using wires, machined posts, cables, printed traces, braids, and other conductive paths.
FIG. 16A illustrates an embodiment in which the feed network is coupled to the radiating elements 140 on the bottom of substrate 110. As illustrated in FIG. 16A, the feed pin 162 extends through a via in the ground plane 160 while the shorting pins 164, 165, 166 are coupled to the ground plane. In operation the shorting pins 164, 165, 166 tune the structure to reduce or eliminate in-band resonances in the feed pins which can cause nulls in RF performance of the antenna element.
FIG. 16B illustrates an embodiment in which the feed network is coupled to the radiating elements 140 on the top of substrate 110. As illustrated in FIG. 16A, the feed pin 162 extends through a via in the ground plane 160 while the shorting pins 164, 165, 166 are coupled to the ground plane. In operation the shorting pins 164, 165, 166 tune the structure to reduce or eliminate in-band resonances in the feed pins which can cause nulls in RF performance of the antenna element.
In practice, a plurality of unit cells 110 may be positioned adjacent one another to define an antenna array. FIG. 17 is a schematic top, plan view of an antenna array formed from a plurality of unit cells 110, according to embodiment, and FIG. 18 is a schematic side elevation view of the antenna array depicted in FIG. 11. In the embodiment depicted in FIGS. 17-18, four antenna unit cells 100 are arranged to form a 2×2 antenna array. One skilled in the art will recognize that any number of unit cells may be combined to form an m×n antenna array.
Referring to FIGS. 17-18, in relevant part when the antenna unit cells 100 are arranged to form a 2×2 array adjacent radiating elements in which the second plurality of radiating elements 140 are separated by a distance that measures twice the distance D1, i.e., 2D1. Thus, referring to FIGS. 16-17, adjacent elements 140A and 140C are separated by a distance of 2D1, as are elements 140B and 140D. By contrast, adjacent radiating elements in the first plurality of radiating elements 120 are in electrical contact with one another. Thus, as illustrated in FIGS. 16-17, radiating elements 120A, 120C are electrically connected, as are radiating elements 120B, 120D.
Referring to FIGS. 7 and 17-18, circular portions of the dielectric substrate 110 are removed proximate the corners of the substrate 110 and the layer 720 above (not shown in FIGS. 17-18). Removing portions of the substrate 110 and the layer 720 above proximate the corners of the substrate 110 and the layer 720 above reduces surface wave propagation across the substrate 110 and the layer 720 above that can cause scan-blindness in an array comprising antenna unit cell 100. One skilled in the art will recognize that removing portions of the substrate 110 and the layer 720 above to reduce scan-blindness can be in various shapes and in a plurality of locations. In alternate embodiments the removal of material may be only in substrate 110 or in the layer 720 above the radiating elements. In an alternate embodiment different shapes and locations may be used in substrate 110 and in the layer 720 above.
In alternate embodiments an antenna unit cell may have different numbers of feed pins 162 and different numbers of shorting pins. A minimum configuration comprises one feed pin 162 and at least one shorting pin 164 for each polarization of the antenna unit cell. Thus, a dual polarization antenna unit cell may comprise 4 pins in total. In alternate embodiments the antenna unit cell may comprise a feed pin 162 and only two short pins, 164, 166 or two short pins 165, 166. Thus, a dual polarization antenna unit cell may comprise 6 pins in total.
In some embodiments the antenna assembly may be formed by printing the respective radiating elements 120, 140 on opposing sides of a sheet of dielectric substrate, as illustrated in FIGS. 5-6 and 13-14 and forming vias in the substrate 110 to permit the feed pin and shorting pins to pass through the substrate 110. One skilled in the art will recognize that the pins can be created by using wires, machined posts, cables, printed traces, braids, and other conductive paths.
Analogous to the assembly depicted in FIG. 7, a conformal antenna assembly the substrate layer 110 and the printed radiating layers 120, 140 may be positioned between one or more foam layers 720 and a ground plane 710. Optionally, a cap layer 730 may be positioned over the foam layer 720. The feed pins 150 may be coupled to a signal source for transmission. The antenna may be mounted on an aircraft or other vehicle, as described with reference to FIG. 8.
Thus, described herein is an ultra-wide band (UWB) antenna unit cell and assembly. The antenna element may be used in the creation of wide-band arrays and/or conformal antennas that achieves ultra wide bandwidth (i.e., a 10:1 frequency band ratio), the ability to perform over wide scan angles, and provides both dual and separable RF polarization capability. In some embodiments the unit cell that employs a multi-layer circuit that comprises a bow-tie fan feed layer, and a layer comprising bow-tie based connected array. The circuit board may be placed over a ground plane with foam dielectric layers below and above the antenna circuit board to create the antenna element structure. A differential feed from bow-tie like fan elements is coupled capacitively to the underlying unit-cell to unit-cell connected bow-tie element layer. Such an antenna has wide applicability to communication phased antenna arrays (PAA), signal intelligence sensors and detection sensor arrays, wide band radar systems, and phased arrays used in electronic warfare.
An antenna element manufactured in accordance herewith exhibits ultra-wide bandwidth and better than 55-degree conical scan volume for the creation of conformal arrays and antennas. The design approach provides effective gain within 2 dB of the ideal gain possible for the surface area of the unit-cell for the element. The element design can be used as a wide-band antenna and/or array. The design can be scaled to any frequency band with a 10:1 or smaller ratio from the highest to the lowest frequency of desired coverage.
While various embodiments have been described, those skilled in the art will recognize modifications or variations which might be made without departing from the present disclosure. The examples illustrate the various embodiments and are not intended to limit the present disclosure. Therefore, the description and claims should be interpreted liberally with only such limitation as is necessary in view of the pertinent prior art.

## Claims

1. An antenna unit cell, comprising:
a dielectric substrate;
a first plurality of radiating elements disposed on a first side of the dielectric substrate, wherein a first radiating element of the first plurality of radiating elements is electrically coupled to a feed connector, and wherein each radiating element of the first plurality of radiating elements is electrically coupled to a ground; and
a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, wherein no radiating element of the second plurality of radiating elements is electrically coupled to any feed connector.

2. The antenna unit cell of claim 1, wherein no radiating element of the second plurality of radiating elements is electrically coupled to the ground.

3. The antenna unit cell of claim 1, wherein the first radiating element is electrically coupled to the feed connector via a feed pin that goes through the dielectric substrate, and wherein the feed pin is not directly coupled to any radiating element of the second plurality of radiating elements.

4. The antenna unit cell of claim 3, wherein each radiating element of the first plurality of radiating elements is electrically coupled to the ground via a corresponding shorting pin of a plurality of shorting pins, wherein each shorting pin of the plurality of shorting pins goes through the dielectric substrate, and wherein no shorting pin of the plurality of shorting pins is directly coupled to any radiating element of the second plurality of radiating elements.

5. The antenna unit cell of claim 4, wherein the first radiating element is electrically coupled to the ground via a first shorting pin of the plurality of shorting pins, and wherein a second radiating element of the first plurality of radiating elements is electrically coupled to the ground via a second shorting pin of the plurality of shorting pins and a third shorting pin of the plurality of shorting pins.

6. The antenna unit cell of claim 1, wherein the first radiating element is electrically coupled to the feed connector via a feed pin that does not go through the dielectric substrate, and wherein the feed pin is not directly coupled to any radiating element of the second plurality of radiating elements.

7. The antenna unit cell of claim 6, wherein each radiating element of the first plurality of radiating elements is electrically coupled to the ground via a corresponding shorting pin of a plurality of shorting pins, wherein no shorting pin of the plurality of shorting pins goes through the dielectric substrate, and wherein no shorting pin of the plurality of shorting pins is directly coupled to any radiating element of the second plurality of radiating elements.

8. An antenna array comprising a plurality of unit cells, a first unit cell of the unit cells comprising:
a dielectric substrate;
a first plurality of radiating elements disposed on a first side of the dielectric substrate, wherein a first radiating element of the first plurality of radiating elements is electrically coupled to a feed connector, and wherein each radiating element of the first plurality of radiating elements is electrically coupled to a ground; and
a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, wherein no radiating element of the second plurality of radiating elements is electrically coupled to any feed connector.

9. The antenna array of claim 8, wherein a second unit cell of the plurality of unit cells is adjacent to the first unit cell, and wherein a hole is defined in the substrate adjacent to the first unit cell and adjacent to the second unit cell.

10. The antenna array of claim 8, wherein the first radiating element is electrically coupled to the feed connector via a feed pin that goes through the dielectric substrate, and wherein the feed pin is not directly coupled to any radiating element of the second plurality of radiating elements.

11. The antenna array of claim 10, wherein each radiating element of the first plurality of radiating elements is electrically coupled to the ground via a corresponding shorting pin of a plurality of shorting pins, wherein each shorting pin of the plurality of shorting pins goes through the dielectric substrate, and wherein no shorting pin of the plurality of shorting pins is directly coupled to any radiating element of the second plurality of radiating elements.

12. The antenna array of claim 11, wherein the first radiating element is electrically coupled to the ground via a first shorting pin of the plurality of shorting pins, and wherein a second radiating element of the first plurality of radiating elements is electrically coupled to the ground via a second shorting pin of the plurality of shorting pins and a third shorting pin of the plurality of shorting pins.

13. The antenna array of claim 8, wherein the first radiating element is electrically coupled to the feed connector via a feed pin that does not go through the dielectric substrate, and wherein the feed pin is not directly coupled to any radiating element of the second plurality of radiating elements.

14. The antenna array of claim 13, wherein each radiating element of the first plurality of radiating elements is electrically coupled to the ground via a corresponding shorting pin of a plurality of shorting pins, wherein no shorting pin of the plurality of shorting pins goes through the dielectric substrate, and wherein no shorting pin of the plurality of shorting pins is directly coupled to any radiating element of the second plurality of radiating elements.

15. An aircraft, comprising:
a communication system; and
an antenna assembly coupled to the communication system and comprising a unit cell, the unit cell comprising:
a dielectric substrate;
a first plurality of radiating elements disposed on a first side of the dielectric substrate, wherein a first radiating element of the first plurality of radiating elements is electrically coupled to a feed connector, and wherein each radiating element of the first plurality of radiating elements is electrically coupled to a ground; and
a second plurality of radiating elements disposed on a second side of the dielectric substrate, opposite the first side, wherein no radiating element of the second plurality of radiating elements is electrically coupled to any feed connector.

16. The aircraft of claim 15, wherein no radiating element of the second plurality of radiating elements is electrically coupled to the ground.

17. The aircraft of claim 15, wherein the first radiating element is electrically coupled to the feed connector via a feed pin that goes through the dielectric substrate, and wherein the feed pin is not directly coupled to any radiating element of the second plurality of radiating elements.

18. The aircraft of claim 17, wherein each radiating element of the first plurality of radiating elements is electrically coupled to the ground via a corresponding shorting pin of a plurality of shorting pins, wherein each shorting pin of the plurality of shorting pins goes through the dielectric substrate, and wherein no shorting pin of the plurality of shorting pins is directly coupled to any radiating element of the second plurality of radiating elements.

19. The aircraft of claim 18, wherein the first radiating element is electrically coupled to the ground via a first shorting pin of the plurality of shorting pins, and wherein a second radiating element of the first plurality of radiating elements is electrically coupled to the ground via a second shorting pin of the plurality of shorting pins and a third shorting pin of the plurality of shorting pins.

20. The aircraft of claim 15, wherein the first radiating element is electrically coupled to the feed connector via a feed pin that does not go through the dielectric substrate, and wherein the feed pin is not directly coupled to any radiating element of the second plurality of radiating elements.