High-insulation ring slot patch radiator for phased-array antenna

Abstract

To provide a low-cost phased-array antenna that provides high-insulation properties between an antenna feeding structure and an RF distribution layer.SOLUTION: An antenna element includes a ring patch and a ring slot for transmitting and receiving radio frequency (RF) signals. The antenna element use several dielectric layers that are separated by a low-dielectric foam layer 1516 upon which the ring patch is arranged. An antenna array includes a top section for communicating RF signals, a bottom section for generating a desired RF signal, and a foam layer between the top section and the bottom section to separate the ring patch from the ring slot. High isolation between the top section and the bottom section allows the antenna elements to be used in higher gain and high-power arrays without adverse feedback issues.SELECTED DRAWING: Figure 15

Description

Technical Field

[0001] Cross - reference to Related Applications

[0001] This application claims priority to U.S. Provisional Application No. 63 / 251,582, filed on October 1, 2021, and entitled "LOW COST ELECTRONICALLY SCANNING ANTENNA ARRAY ARCHITECTURE", and U.S. Patent Application No. 17 / 588,172, filed on January 28, 2022, and entitled "LOW COST ELECTRONICALLY SCANNING ANTENNA ARRAY ARCHITECTURE", the entire disclosures of which are hereby incorporated by reference in their entirety.

[0002]

[0002] Embodiments generally relate to a phased array antenna ("PAA") that provides for the reception and transmission of radio frequency (RF) signals. In particular, embodiments relate to a low - cost PAA that provides high isolation between an antenna feed structure and an RF distribution layer.

Background Art

[0003]

[0003] A phased array antenna ("PAA") is a type of antenna that includes a plurality of sub - antennas (commonly known as antenna elements, array elements, or radiating elements of a composite antenna), and the relative amplitudes and phases of the respective signals feeding the array elements can be varied so that the effect on the overall radiation pattern of the PAA is enhanced in a desired direction and suppressed in an undesired direction. In other words, beams can be generated that are directed or steered in different directions. Beam pointing in a transmit or receive PAA is achieved by controlling the amplitude and phase of the signals transmitted or received from each antenna element within the PAA.

[0004]

[0004] The individual radiated signals are combined to form constructive and destructive interference patterns generated by the PAA, resulting in one or more antenna beams. The PAA can then be used to quickly direct the one or more beams in azimuth and elevation.

[0005]

[0005] However, some existing solutions provide relatively low insulation between the antenna element or antenna feeding structure and the radio frequency (RF) distribution element or distribution layer. Such a configuration may suffer from feedback problems as the size (e.g., number of elements) and power of the antenna array increase. As a result, there is a need for a PAA that provides high insulation between the antenna feeding structure and the RF distribution layer.

SUMMARY OF THE INVENTION

[0006]

[0006] The disclosed embodiments are described in detail below with reference to the accompanying drawings listed below. The following summary is provided to explain the disclosed embodiments or implementations. However, it is not intended that all embodiments be limited to any specific configuration or sequence of operations.

[0007]

[0007] The disclosed embodiments and implementations are directed to antenna elements that can be arranged together to form an antenna array (or PAA). The disclosed antenna elements use several stacked dielectric layers, at least two of which are separated by a low-dielectric foam layer. The horizontal upper dielectric layer supports a microstrip square-ring patch radiator and also serves as an environmental shield against corrosion. The cutout holes in the square-ring patch lower the resonance frequency of the patch and allow for a smaller outer diameter. The smaller outer diameter is desirable for reducing mutual coupling and avoiding overemphasis of the gain of the broadside antenna.

[0008]

[0008] The disclosed antenna elements can be arranged together within an antenna array that is adjustable to collectively generate or receive RF signals. In particular, the antenna array functions as a transmit / receive half-duplex antenna of 256 elements and operates in either the transmit or receive mode at any time, but the transmit and receive modes do not operate simultaneously. The antenna array includes a radiator block, a transmit / receive (T / R) amplifier block, a beamformer block, and a distribution network block.

[0009]

[0009] Another disclosed plurality of embodiments and aspects are directed to a unit cell antenna system for a periodic antenna array. The system includes an upper section for communicating a radio frequency (RF) signal, the upper section including a dielectric layer and a ring patch, the ring patch being supported by the dielectric layer and having a central cutout hole for reducing the resonant frequency of the ring patch, a lower section for generating a desired radio frequency (RF) signal, the lower section including a plurality of dielectric layers, a ring slot supported by one of the plurality of dielectric layers, a conductive fence substantially surrounding the ring slot, two feeding lines, the feeding lines being 90 degrees out of phase, and a foam layer disposed between the upper section and the lower section, the foam layer separating the ring patch from the ring slot.

[0010]

[0010] Still other disclosed embodiments and implementations are directed to a method for providing a unit cell antenna for a periodic antenna array. The method includes providing an upper section for communicating a radio frequency (RF) signal, the upper section including a dielectric layer and a ring patch, the ring patch being supported by the dielectric layer and having a central cutout hole for reducing the resonant frequency of the ring patch; providing a lower section for generating a desired radio frequency (RF) signal, the lower section including a plurality of dielectric layers, a ring slot supported by one of the plurality of dielectric layers, a conductive fence substantially surrounding the ring slot, and two feed lines having a 90-degree phase shift; and providing a foam layer disposed between the upper section and the lower section for separating the ring patch from the ring slot.

[0011]

[0011] Still other disclosed embodiments and implementations are directed to a method of manufacturing a unit cell antenna system for a periodic antenna array. The method includes forming an upper section for communicating a radio frequency (RF) signal, the upper section including a dielectric layer and a ring patch, the ring patch being supported by the dielectric layer and having a central cutout hole for reducing the resonant frequency of the ring patch; forming a lower section for generating a desired radio frequency (RF) signal, the lower section including a plurality of dielectric layers, a ring slot supported by one of the plurality of dielectric layers, a conductive fence substantially surrounding the ring slot, and two feed lines having a 90-degree phase shift; and forming a foam layer disposed between the upper section and the lower section for separating the ring patch from the ring slot.

[0012]

[0012] Other technical features will be readily apparent to those skilled in the art from the following drawings, description, and claims.

[0013]

[0013] To more fully understand the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which like numerals represent like parts.

Brief Description of the Drawings

[0014]

Figure 1

[0014] A perspective view of a ring cell having a conductive fence according to some of the disclosed embodiments is shown.

Figure 2

[0015] A cut-away side view of a ring cell having a conductive fence according to some of the disclosed embodiments is shown.

Figure 3

[0016] A top view of an antenna array made of a plurality of ring cells according to some of the disclosed embodiments is shown.

Figure 4

[0017] A perspective view of a ring cell having a circular via fence according to some of the disclosed embodiments is shown.

Figure 5A

[0018] A perspective view of a ring cell having a T-junction delay feeder according to some of the disclosed embodiments is shown.

Figure 5B

Figure 6A

[0019] A perspective view of a ring cell having a 90-degree hybrid coupler according to some of the disclosed embodiments is shown.

Figure 6B

Figure 7

[0020] A block diagram of an antenna system for an antenna array made of a ring cell disclosed in the present disclosure is shown.

Figure 8

[0021] A perspective view of an aircraft having one or more array antennas fabricated with ring cells disclosed in the present disclosure is shown.

Figure 9

[0022] An antenna integrated printed wiring board (AIPWB) for an antenna array constructed with several ring cells, according to some of the disclosed embodiments, is shown.

Figure 10

[0023] Another AIPWB for an antenna array constructed with several ring cells, according to some of the disclosed embodiments, is shown.

Figure 11

[0024] A schematic diagram of a 16-ring cell subarray using a kind of beamformer and a front-end integrated circuit (IC), according to some of the disclosed embodiments, is shown.

Figure 12

[0025] Layer 1 of the interface for the MMIC for the 16-ring cell subarray antenna 1100 is shown.

Figure 13

[0026] A block diagram of a transmit / receive antenna array for line-of-sight applications, according to some of the disclosed embodiments, is shown.

Figure 14

[0027] A perspective view of a ring cell having a conductive fence with a plurality of additional adhesive layers, according to some of the disclosed embodiments, is shown.

Figure 15

[0028] A cut-away side view of a ring cell having a conductive fence with a plurality of additional adhesive layers, according to some of the disclosed embodiments, is shown.

Figure 16

[0029] A top view of an antenna array fabricated with a plurality of ring cells, according to some of the disclosed embodiments, is shown.

Figure 17

[0030] A perspective view of a ring cell having a circular via fence with a plurality of additional adhesive layers, according to some of the disclosed embodiments, is shown.

Figure 18A

[0031] A perspective view of a ring cell having a T-junction delay feeder line according to some of the disclosed embodiments is shown.

Figure 18B

Figure 19A

[0032] A perspective view of a ring cell having a 90-degree hybrid coupler according to some of the disclosed embodiments is shown.

Figure 19B

Figure 20

[0033] An example of an antenna array fabricated with a plurality of ring cells according to some of the disclosed embodiments is shown.

Figure 21

[0034] A block diagram of an example of an antenna system fabricated with the ring cells disclosed in the present disclosure is shown.

Figure 22

[0035] An antenna integrated printed wiring board (AIPWB) for an antenna array constructed with several ring cells according to some of the disclosed embodiments is shown.

Figure 23

[0036] A partial view of an example of an antenna array fabricated with the disclosed ring cells is shown.

Figure 24

[0037] A method for providing a unit cell antenna for a periodic antenna array according to some of the disclosed embodiments is shown.

Figure 25

[0038] A method for manufacturing a unit cell antenna system for a periodic antenna array according to some of the disclosed embodiments is shown.

DETAILED DESCRIPTION OF THE INVENTION

[0015]

[0039] Corresponding reference numerals indicate corresponding parts throughout the accompanying drawings.

[0016]

[0040] Various embodiments will be described in detail with reference to the accompanying drawings. Whenever possible, the same reference numbers are used throughout the drawings to refer to the same or similar parts. References to specific embodiments and aspects throughout this disclosure are for illustrative purposes only and are not intended to limit all embodiments, unless the contrary is suggested.

[0017]

[0041] A phased array antenna (PAA) includes a plurality of emitters and is used for beamforming in high-frequency RF applications such as radar, 5G, or countless other applications. The number of emitters in a PAA ranges from a few to thousands. The purpose of using a PAA is to control the direction of the emitted beam by taking advantage of the constructive interference between two or more radiated signals. This is known in the antenna industry as "beamforming".

[0018]

[0042] More specifically, a PAA enables beamforming by adjusting the phase difference between the drive signals transmitted to each emitter in the array. This makes it possible to control the radiation pattern and direct it towards a target without the need to physically move the antenna. This means that beamforming along a specific direction is the interference effect between quasi-omnidirectional emitters (e.g., dipole antennas).

[0019]

[0043] The disclosed embodiments and examples provide a low-cost Ku-band electronically scanned antenna array architecture that integrates one or more low-complexity apertures, coupled hybrid patch radiators, and commercially available monolithic microwave integrated circuits (MMICs) using a low-cost multilayer printed wiring board design known as an antenna integrated printed wiring assembly (AIPWA). In particular, a ring-shaped antenna element (referred to herein as a "ring cell") is described that provides an ultra-low-cost unit cell antenna element with a unique feeding structure for electronically scanned arrays. A dielectric substrate layer for supporting a microstrip ring patch radiator is included in the upper section of the antenna element. The lower section has one layer of dielectric substrate for supporting a ring slot and a dual feed line. The disclosed antenna element provides high-quality antenna performance over a wide frequency bandwidth, a one-dimensional scan range up to + / - 45 degrees, and dual linear polarization and circular polarization.

[0020]

[0044] The ring cell includes a unique feeding structure for PAA or other electronically scanned arrays. The ring cell is composed of a circuit board base section and a foam spacer. The upper section has one layer of dielectric substrate for supporting a microstrip ring patch radiator. The lower section has two layers of dielectric substrate for supporting a ring slot, a dual feed line, and a metal fence. The disclosed ring cell provides high-quality antenna performance over a wide frequency band and a large scan space. The ring cell also provides dual linear polarization or circular polarization. The disclosed ring cell does not use mechanical moving parts and eliminates much of the complexity and failure points of conventional antenna cells.

[0021]

[0045] The disclosed ring cells can be arranged within an array antenna (e.g., PAA) that collectively functions as an electronic scanning antenna array beam. The array antenna using the disclosed ring cells can be used in many real-world applications. For example, airplanes, automobiles, various military systems, Internet of Things (IoT) devices, and any device using RF signals can be equipped with an array antenna using the disclosed ring cells. The disclosed ring cells and antenna arrays provide an electronic scanning antenna system that dramatically reduces the integration cost due to both a thin design and the use of commercially available materials at an affordable price.

[0022]

[0046] Conventionally, ceramic chip carrier modules have been used as the interface between MMIC and AIPWB. Such ceramic packages are relatively expensive and require costly manual labor for assembly. Not only that, ceramic packages also use a bulky and complex waveguide radiator that adds a stacking step and redundant layers to the AIPWB. The waveguide radiator requires an expensive and complex wide-angle impedance matching (WAIM) structure as the interface between the antenna array and free space. Unfortunately, this cannot meet the cost per element targeted by many customers utilizing line-of-sight communications.

[0023]

[0047] The disclosed embodiments and examples use a low-complexity aperture-coupled patch radiator, a low-cost commercially available surface-mount MMIC, and a low-cost multilayer printed wiring board stack-up. The low-complexity aperture-coupled patch radiator reduces the AIPWB layer count by 50% and eliminates the WAIM components without sacrificing the RF performance of the antenna within the range of + / −45-degree angle-of-attack scanning. By using a low-cost commercially available MMIC in surface mount, the cost per element of the antenna array can be reduced to less than one-third. The stack-up of the low-cost and less complex multilayer printed wiring board reduces the manufacturing cost and opens up the manufacturing to a more diverse supplier.

[0024]

[0048] The disclosed ring cell can transmit and receive RF signals with vehicles and aircraft using a nimble electronic scanning antenna array beam without mechanical moving parts. The antenna elements can be assembled into an antenna array. The antenna array can be used in many applications such as, for example, but not limited to, radar, sensors, or other applications. The antenna elements provide a high-performance, lightweight, thin, and ultra-low-cost solution to meet challenging and evolving mission requirements. Further, the disclosed antenna elements are used in the manufacture of integrated, structurally integrated antennas (especially in composite sandwich panels because the use of vias and connections can be minimized).

[0025]

[0049] FIG. 1 shows a perspective view of a ring cell 100 having a conductive fence 102 (a "ring fence" 102) according to some of the disclosed embodiments. The ring cell 100 includes several circuit board-based sections. In addition to the conductive fence 102, the ring cell 100 includes a ring patch 104, two feed lines 106 and 108, a ring slot 110, an upper dielectric layer 112, an upper adhesive layer 114, a foam layer 116, an upper inner adhesive layer 118, an inner metal layer 120, an intermediate dielectric layer 122, and a lower dielectric layer 126. In some embodiments, the foam layer 116 includes a foam layer that separates the ring slot 110 from the ring patch 104 and is thus referred to herein as the "foam layer" 116. In some examples, the various dielectric layers 112, 122, and 126 are printed circuit boards (PCBs). Further, the ring patch 104 can be formed, etched, or adhered to the foam layer 116 to hold the ring patch 104 in place.

[0026]

[0050] The conductive fence 102 includes one or more metal (or otherwise conductive) walls. An alternative design shown in FIG. 4 replaces the metal walls with an electrical via in a circular pattern.

[0027]

[0051] More specifically, the horizontal upper section of the ring cell 100 includes the upper dielectric layer 112. The upper dielectric layer 112 supports the underlying ring patch 104 and also serves as an environmental shield against corrosion. The ring patch 104 includes cutout holes that lower the resonance frequency of the patch and allow for a smaller outer diameter. The smaller outer diameter is desirable for reducing mutual coupling and avoiding overemphasis of the gain of the broadside antenna.

[0028]

[0052] The lower section of the ring cell 100 includes two layers of the dielectric substrate, namely, the intermediate dielectric layer 122 and the lower dielectric layer 126. Collectively, these support the ring slot 110, the dual feed lines 106 and 108, and the thin conductive fence 102. The feed lines 106 and 108 supply power to excite the orthogonal resonance modes within the ring slot 110. This, in turn, then excites the orthogonal resonance modes within the upper ring patch 104 for the RF signal. When transmitting an RF signal, the feed lines supply power (voltage and current) to generate an electrical resonance within the ring 110. This, in turn, then generates the desired RF signal within the ring patch 104. When receiving an RF signal, the feed lines receive the power induced within the ring 110 from the ring patch 104 that received the RF signal.

[0029]

[0053] The ring slot 110 and the ring patch 104 cooperate to provide a wider impedance bandwidth than either one alone could provide. Thus, the ring cell 100 is designed to operate as a hybrid radiator that functions in both transmit and receive modes. Alternatively, the ring cell 100 can operate in transmit mode only or receive mode only.

[0030]

[0054] The conductive fence 102 shields the ring slot 110 from the RF power distribution network and reduces unwanted mutual coupling with other ring slots 110 in adjacent ring cells 100 that are part of an array antenna (e.g., PAA). The diameter and depth of the conductive fence 102 are set such that the ring slot 110 resonates at or near the desired operating frequency band. In some embodiments, the openings 128 and 130 around the conductive fence 102 allow the feed lines 106 and 108 to enter inward without being electrically shorted.

[0031]

[0055] The ring patch 104 and the conductive fence 102 are metallic or otherwise conductive. Electricity is supplied to the ring cell 100 through the feed lines 106 and 108, and the ring fence 102 and the ring patch 104 are operated as radiating elements for generating a specific RF signal. In shape, the conductive fence 102 has a diameter larger than that of the ring slot 110. This allows the ring slot 110 to be horizontally disposed inside the conductive fence 102. However, as can be seen in FIG. 2, in at least some embodiments, the ring slot 110 is disposed vertically above the conductive fence 102.

[0032]

[0056] The dual feed lines 106 and 108 excite the orthogonal dual linear polarizations required in some applications. In other applications, dual or single circular polarizations may be required. Alternatively, some embodiments include a feeding structure that uses a T-junction diplexer / combiner (transmit / receive respectively) and a 90-degree delay line for right-hand circular polarization, as shown in FIGS. 5A and 5B. This integrated coplanar feeding provides an economical way to achieve optimal polarization performance in the far field. Left-hand circular polarization can also be achieved by moving the L-shaped input line section from its current position to the opposite side of the V-shaped junction. To improve circular polarization performance over scanning, some other embodiments use different feeding structures that use 90-degree hybrid couplers, as shown in FIGS. 6A and 6B.

[0033]

[0057] The illustrated ring cell 100 disclosed herein is shaped in a hexagonal pattern. However, other shapes are equally well considered. For example, the ring cell 100 can be circular, rectangular, square, etc. In these non-hexagonal ring cells 100, some embodiments still use a circular ring patch 104, a ring slot 110, and a conductive fence 102.

[0034]

[0058] FIG. 2 shows a cut-away side view of a ring cell 100 having a conductive fence 102 according to some of the disclosed embodiments. As shown, the ring patch 104 is disposed above the upper adhesive layer 114 and below the dielectric layer 112. The foam layer 116 separates the upper adhesive layer 114 from the ring slot 110. Specifically, the foam layer 116 is disposed between the upper adhesive layer 114 and the upper inner adhesive layer 118. The ring slot 110 is disposed within the inner metal layer 120. The conductive fence 102 extends across the intermediate dielectric layer 122, the lower adhesive layer 124, and the lower dielectric layer 126.

[0035]

[0059] One disclosed example shows feed lines 106 and 108 disposed within the upper half in the vertical direction of the conductive fence 102. The dotted line 202 indicates the middle in the vertical direction of the conductive fence 102. As can be seen, the feed lines 106 and 108 are disposed within the upper half 204 rather than the lower half 206.

[0036]

[0060] FIG. 3 shows a top view of an antenna array 300 fabricated with a plurality of ring cells 100a - d according to some of the disclosed embodiments. This figure shows an example of the feed lines 106a - d and 108a - d of various ring cells 100a - d having a 90-degree rotation. In other words, the feed lines 106a and 108a are rotated 90 degrees from the positions of the feed lines 106b and 108b. This arrangement suppresses the undesired cross-polarization signal level in the far field.

[0037]

[0061] Alternative designs that do not use the conductive fence 102 are shown in FIGS. 4-6B. Instead of the conductive fence, these alternative embodiments form a circular fence using an assembly of electrical vias.

[0038]

[0062] In accordance with these concepts, FIG. 4 shows a perspective view of a ring cell 400 having a circular via fence 402 according to some of the disclosed embodiments. The ring cell 400 includes a ring patch 404, two feed lines 406 and 408, a ring slot 410, an upper dielectric layer 412, an upper adhesive layer 414, a foam layer 416, an upper inner adhesive layer 418, an inner metal layer 420, an intermediate dielectric layer 422, and a lower dielectric layer 426. These various components are arranged in the same manner as the ring cell 100 described above. However, instead of the conductive fence 102, the ring cell 400 includes electrical vias 402a-n. The electrical vias 402a-n are arranged in a circular pattern around the ring slot 410 and collectively form a via fence having a number of openings 430-436 (only four are labeled).

[0039]

[0063] Similar to the ring cell 100, the horizontal upper section of the ring cell 400 includes the upper dielectric layer 412. The upper dielectric layer 412 supports the underlying ring patch 404 and also serves as an environmental shield against corrosion. The ring patch 404 includes cutout holes that lower the resonance frequency of the patch and allow for a smaller outer diameter. The smaller outer diameter is desirable for reducing mutual coupling and avoiding over-emphasis of the gain of the broadside antenna.

[0040]

[0064] The lower section of the ring cell 400 includes two layers of a dielectric substrate, namely, the intermediate dielectric layer 422 and the lower dielectric layer 426. These collectively support the ring slot 410, the dual feed lines 406 and 408, and the via fence formed by the electrical vias 402a - n. The feed lines 406 and 408 excite the orthogonal resonance modes within the ring slot 410. This, in turn, then excites the orthogonal resonance modes within the ring patch 404 described above. The ring slot 410 and the ring patch 404 cooperate to provide a wider impedance bandwidth than either one alone could provide. Thus, the ring cell 400 is designed to operate as a hybrid radiator that operates in both transmit and receive modes. Alternatively, the ring cell 400 can operate in only the transmit mode or only the receive mode.

[0041]

[0065] The ring patch 404 and the electrical vias 402a - n are metallic or otherwise conductive. Electricity is supplied to the ring cell 400 through the feed lines 406 and 408, and the electrical vias 402a - n and the ring patch 404 are operated as radiating elements to generate a specific RF signal. In terms of shape, the via fence has a diameter larger than that of the ring slot 410. This enables the ring slot 410 to be horizontally disposed inside the conductive fence 402.

[0042]

[0066] The via fence created by the electrical vias 402a - n also shields the ring slot 410 from the power distribution network and reduces the unwanted mutual coupling with other ring slots 410 in adjacent ring cells 400 that are part of an array antenna (e.g., PAA). The diameter and depth of the via fence are set such that the ring slot 410 resonates at or near the desired operating frequency band. In some embodiments, the openings around the electrical via conductive fence 402 allow the feed lines 406 and 408 to enter inward without being electrically short - circuited.

[0043]

[0067] The power supply lines 406 and 408 are arranged in the upper half in the vertical direction of the electrical vias 402a - n.

[0044]

[0068] FIGS. 5A and 5B respectively show a perspective view and a top view of a ring cell 400 having a T - junction delay power supply line 500 according to some of the disclosed embodiments. The T - junction delay power supply line 500 includes two power supply lines (a shorter power supply line 502 and a longer L - shaped power supply line 504). The two power supply lines extend from a single input / output (I / O) line 506. In circular polarization formation in RF signals transmitted or received through the ring cell 400, the power supply line 504 is longer than the power supply line 502. These separate power supply lines 502 and 504 are arranged at 90 degrees to each other. Although the design of the ring cell 400 with the electrical vias 402a - n is illustrated, the T - junction delay power supply line 500 may be used in the ring cell 100 having the conductive fence 102.

[0045]

[0069] The illustrated T - junction delay power supply line 500 provides a right - hand circular polarization and supplies an optimal polarization in the far - field. A left - hand circular polarization can also be achieved by moving the longer L - shaped power supply line 504 from the illustrated position to the other side of the V - shaped junction.

[0046]

[0070] The illustrated T - junction delay power supply line 500 can also be used in the ring cell 100 instead of the illustrated ring cell 400. The ring cell 400 is shown only in FIGS. 5A - 5B as an example of a ring cell having a T - junction delay power supply line 500.

[0047]

[0071] FIGS. 6A and 6B show, respectively, a perspective view and a top view of a ring cell having a 90-degree hybrid coupler 600 according to some of the disclosed embodiments. The hybrid coupler 600 includes two feed lines 602 and 604 and an elliptical (or circular) path line 606. In some embodiments, the feed lines 602 and 604 are arranged at 90 degrees from each other. The hybrid coupler 600 includes two terminals 608 and 610. Terminal 608 acts as an input or output of voltage depending on whether the ring cell transmits or receives an RF signal. Terminal 610 is connected to an electrical via 612. The electrical via 612 penetrates the lower dielectric layer 426 and is electrically coupled to a resistor 614. During operation, this hybrid coupler 600 improves the circular polarization performance.

[0048]

[0072] The illustrated hybrid coupler 600 can also be used in the ring cell 100 instead of the illustrated ring cell 400. The ring cell 400 is shown only in FIGS. 6A-6B as an example of a ring cell having a hybrid coupler 600.

[0049]

[0073] FIG. 7 shows a block diagram of an antenna system 700 for an antenna array 702 fabricated with the ring cells 100a-n disclosed in the present disclosure. In this embodiment, the antenna system 700 includes a power supply 704, a controller 706, and an antenna array 702. In this embodiment, the antenna array 702 is a phased array antenna (``PAA'') that includes a plurality of ring cells 102a-n that operate as either a transmit and / or receive module. The ring cells 100a-n include corresponding radiating elements. The corresponding radiating elements can be combined to transmit and / or receive an RF signal. For example, the ring cells 100a-n can be configured to operate within the K-band frequency range (e.g., from about 20 GHz to 40 GHz in the NATO K-band, from 18 GHz to 26.5 GHz in the IEEE K-band).

[0050]

[0074] Power supply 704 is a device, component, and / or module that provides power to controller 706 within antenna system 700. Controller 706 is a device, component, and / or module that controls the operation of antenna array 702. Controller 706 can be a processor, microprocessor, microcontroller, digital signal processor ("DSP"), or other type of device that can be programmed with either hardware and / or software. Controller 706 controls the power feed provided to antenna array 702, including, but not limited to, calibrating specific polarization, voltage, frequency, etc. of the power feed. For clarity, only one line is shown between controller 706 and antenna array 702, but in reality, several electrical connections and supply lines can connect controller 706 to antenna array 702.

[0051]

[0075] In some embodiments, controller 706 performs specific power feeding to various ring cells 100a - n so as to generate a number of RF signals that are combined either constructively or destructively to form the desired cumulative RF signal for transmission.

[0052]

[0076] The RF signals emitted from each of the ring cells 100a - n within array antenna 702 may be in - phase to generate constructively strong radiation, or may be out - of - phase to generate specific RF signals destructively. The direction can be controlled by setting the phase shift between the signals transmitted to different ring cells 100a - n. The phase shift can be controlled by controller 706 by introducing a small time delay between the signals transmitted to consecutive ring cells 100a - n within the array.

[0053]

[0077] Antenna system 700 is described as communicating signals with each other. In that case, signal communication refers to any kind of communication and / or connection between circuits, components, modules, and / or devices that enables a circuit, component, module, and / or device to transmit and receive signals and / or information between another circuit, component, module, and / or device. The communication and / or connection can be along any signal path between circuits, components, modules, and / or devices that enables signals and / or information to be transmitted from one circuit, component, module, and / or device to another, which includes wireless or wired signal paths. The signal path can be physical, such as, for example, a conductor, an electromagnetic waveguide, a cable, attached and / or electromagnetically or mechanically coupled terminals, a semiconductor, or a dielectric material, or a device, or other similar physical connections or couplings. Further, the signal path can be a non-physical path. A non-physical path is, for example, an information path through free space (in the case of electromagnetic propagation) or through digital components, where communication information is transmitted in various digital forms from one circuit, component, module, and / or device to another without passing through a direct electromagnetic connection.

[0054]

[0078] This antenna system 700 provides means for transmitting (or receiving) RF signals to (or from) an airborne / mobile vehicle with a nimble electronically scanned antenna array beam without mechanical moving parts. The antenna system 700 can be used in communication systems and other applications, including, but not limited to, radar / sensors, electronic warfare, military applications, mobile communications, etc. The antenna system 700 provides a high-performance, lightweight, thin, and affordable solution to meet difficult and evolving mission requirements.

[0055]

[0079] FIG. 8 shows a perspective view of an aircraft having an antenna array 702 according to various embodiments of the present disclosure. The aircraft 800 includes wings 802 and 804 attached to a fuselage 806. The aircraft 800 also includes an engine 808 attached to the wing 802 and an engine 810 attached to the wing 804. The fuselage 806 has a tail 812. A horizontal stabilizer 814, a horizontal stabilizer 816, and a vertical stabilizer 818 are attached to the tail 812 of the fuselage 806. In some embodiments, the fuselage 806 has a composite outer skin 820.

[0056]

[0080] In some embodiments, the antenna system 700 described above may be included on or within the aircraft 800. The antenna system 700 individually includes only the ring cell 100, or the ring cell 100 within the disclosed antenna array 702. This is shown by the dashed frame in FIG. 8. The antenna system 700 may be disposed inside or outside the aircraft 800.

[0057]

[0081] The illustration of the aircraft 800 is not intended to suggest physical or structural limitations on how an exemplary configuration may be implemented. For example, the aircraft 800 is a commercial aircraft, but the aircraft 800 may be a military aircraft, a rotary-wing aircraft, a helicopter, an unmanned aerial vehicle, or any other suitable aircraft. Other vehicles are similarly possible. By way of non-limiting example, automobiles, motorcycles, buses, boats, trains, etc.

[0058]

[0082] Conventionally, a ceramic chip carrier module has been used as an interface between an MMIC and an AIPWB. Such a ceramic package is relatively expensive and requires costly manual labor for assembly. Moreover, the ceramic package also uses a bulky and complex waveguide radiator that adds a lamination step and surplus layers to the AIPWB. The waveguide radiator requires an expensive and complex wide-angle impedance matching (WAIM) structure as an interface between the antenna array and free space. Unfortunately, this cannot meet the cost per element targeted by customers who utilize many line-of-sight communications.

[0059]

[0083] The disclosed embodiments and examples use a low-complexity aperture-coupled patch radiator, a low-cost commercially available surface-mount MMIC, and a low-cost multilayer printed wiring board stack-up. The low-complexity aperture-coupled patch radiator reduces the AIPWB layer count by 50% and eliminates the WAIM components within the range of a + / -45-degree angle of incidence without sacrificing the RF performance of the antenna. By using a low-cost commercially available MMIC for surface mounting, the cost per element of the antenna array can be reduced to less than one-third. The low-cost and reduced-complexity multilayer printed wiring board stack-up reduces manufacturing costs and opens up manufacturing to a more diverse supplier base.

[0060]

[0084] The disclosed ring cell can transmit and receive RF signals between a vehicle or an aircraft with an agile electronically scanned antenna array beam without any mechanical moving parts. The antenna elements can be assembled into an antenna array. The antenna array can be used in many applications, such as, but not limited to, radar, sensors, or other applications. The antenna elements provide a high-performance, lightweight, thin, and ultra-low-cost solution to meet difficult and evolving mission requirements. Furthermore, the disclosed antenna elements are used in the manufacture of integrated and structurally integrated antennas (especially in composite sandwich panels because the use of vias and connections can be minimized).

[0061]

[0085] Figure 9 shows an AIPWB 900 for an antenna array 702 constructed with several ring cells 100 according to some of the disclosed embodiments. The AIPWB 900 includes nine vias (1 - 9) and various laminations (1, 2, 3), one of which is divided into two separate sub - laminations (1A and 1B). Sub - lamination 1A includes layers 1 through 6 and provides control and power wiring for the MMIC using a single drill step and the RF interconnect of layer 1. Sub - lamination 1B covers layers 7 through 9 and is an RF asymmetric stripline. The RF asymmetric stripline provides RF distribution across the antenna array 702 to the quad (or other multiplier) element beamforming MMIC, as well as provides a feed structure to the aperture - coupled patch. Sub - lamination 1B has one drill step for RF suppression vias used for insulation between the radiating structure and the RF distribution network. Lamination 2 can have coast - to - coast layer 1 through layer 9 vias implemented as shown in FIG. 9. Alternatively, as shown in FIG. 10, the electrical bonding of sub - laminations 1A and 1B can be realized with an Ormet paste process. Lamination 3 connects the entire PCB structure with a foam spacer (e.g., foam layer 116) and an electrically isolated radiating patch on layer 10.

[0062]

[0086] Figure 10 shows another AIPWB 1000 for an antenna array 702 constructed with several ring cells 100 according to some of the disclosed embodiments. The AIPWB 1000 is still an aperture-coupled patch antenna array element that suppresses surface modes across the array, limits mutual coupling, and does not require vertical interconnections between radiation layers. The AIPWB 1000 dramatically reduces the complexity of the PCB compared to conventional line-of-sight (LOS) radiator designs. The new aperture-coupled patch antenna array element supports a grating lobe-free scan volume with an elevation angle of + / - 45 degrees over all azimuth angles without scan blindness. Using the AIPWB 1000, the antenna array 702 can be pushed to scan beyond 45 degrees, but a steeper gain roll-off is expected when operating in these scan regions.

[0063]

[0087] In some embodiments, the antenna array 702 uses a mature full-featured commercially available half-duplex phased array chipset. Such a chipset is operable at 8 - 16 GHz in some examples. In some embodiments, the chipset is composed of two land grid array (LGA) MMICs. That is, a quad element SiGe beamformer and an RF front-end IC composed of a low noise amplifier (LNA) with a single-pole double-throw (SPTD) switch.

[0064]

[0088] FIG. 11 shows a schematic diagram of a conventional 16-ring cell subarray antenna 1100 using a kind of beamformer and a front-end integrated circuit (IC) according to some embodiments. A quad element beamformer is shown, but any beamformer may be used. The 16-ring cell subarray antenna 1100 includes a plurality of antenna arrays 702 having various ring cells 100 / 400. A single 4-wire serial peripheral interface (SPI) bus controls the subarray of 16 elements. In some embodiments, these 16-ring cell subarray antennas 1100 are tiled together on a PCB panel to generate any 16n element array (where n is an integer greater than or equal to 1). The 16-ring cell subarray antennas 1100 are not limited to MMICs and can be easily modified to be compatible with different commercially available MMIC chip sets.

[0065]

[0089] Figure 13 shows a block diagram of a transmit / receive antenna array 1300 for LOS applications, according to some of the disclosed embodiments. In some embodiments, the antenna array 1300 functions as a transmit / receive half-duplex antenna of 256 elements and operates in either transmit or receive mode at any time, but the transmit and receive modes do not operate simultaneously. In particular, the antenna array 1300 includes a radiator block 1301, a transmit / receive (T / R) amplifier block 1302, a beamformer block 1304, and a distribution network block 1306. The radiator block 1301 includes a dual linear polarization patch antenna having two vertically disposed elements, a horizontal element 1308 and a vertical element 1310. The T / R amplifier block 1302 includes a power amplifier 1312, a front-end switch 1314, and a low-noise amplifier 1316. The beamformer block 1304 includes a driver amplifier 1318, 7-bit equivalent (or other) phase shifters 1320 and 1328, variable operational amplifiers (op amps) 1322 and 1326, a back-end switch 1324, and a low-noise amplifier 1328. The beamformer block 1304 can take the form of a dual, quad, or other multi-element beamformer. The distribution block 1406 includes a splitter 1330 and an RF port 1332, the latter being for receiving an RF input for transmission or for directing a received RF input.

[0066]

[0090] The front-end switch 1314 and the back-end switch 1324 are controlled to selectively configure the antenna array 1300 in transmit or receive mode. One illustrated embodiment shows the antenna array 1300 in transmit mode. Alternatively, both the front-end switch 1314 and the back-end switch 1324 can be switched to other slower settings for receive mode.

[0067]

[0091] When operating in the transmission mode, RF input 1332 is received and split into 64 ways by splitter 1330. These 64 break signals are passed through back-end switch 1324 to op-amp 1322, phase shifter 1320, and power amplifier 1312, and then supplied to radiator block 1301 through front-end switch 1314. In radiator block 1301, the RF signal is transmitted.

[0068]

[0092] When operating in the reception mode, the RF input is received by radiator block 1301. This received RF signal is passed through front-end switch 1314 to low-noise amplifiers 1316 and 1328, phase shifter 1328, and power amplifier 1326. The amplified RF signal is then provided to exit through RF port 1332 through back-end switch 1320 and through splitter 1330.

[0069]

[0093] The above-described disclosed embodiments provide many advantages, but there remains an opportunity to improve the signal insulation between the antenna element or antenna feeding structure and the radio frequency (RF) distribution element or distribution layer in order to avoid feedback problems. This is especially true when the size of the antenna array (e.g., the number of elements) and the power increase. As a result, a PAA that provides high insulation between the antenna feeding structure and the RF distribution layer is needed. High insulation can be achieved by embedding a symmetric strip line RF distribution layer in the asymmetric strip line of the antenna feeding structure. As a result, the high insulation between the antenna feeding structure and the RF distribution layer enables the antenna element to be used in arrays with higher gain and higher output.

[0070]

[0094] FIG. 14 shows a perspective view of a ring cell 1400 having a conductive fence 1402 (the “ring fence” 1402) according to some of the disclosed embodiments. Similar to the ring cell 100, the ring cell 1400 includes a number of circuit board based sections. In addition to the conductive fence 1402, the ring cell 1400 includes a ring patch 1404, two feed lines 1406 and 1408, a ring slot 1410, an upper dielectric layer 1412, an upper adhesive layer 1414, a foam layer 1416, an upper internal adhesive layer 1418, an internal metal layer 1420, an intermediate dielectric layer 1422, and a lower dielectric layer 1426. Different from the ring cell 100, the ring cell 1400 includes a plurality of additional layers (e.g., “lower” dielectric layers and adhesive layers) in at least some embodiments. For example, some embodiments may include an upper lower adhesive layer 1442, an upper lower dielectric layer 1444, a lower lower adhesive layer 1446, and a lower lower dielectric layer 1448. In some embodiments, the foam layer 116 includes a foam layer that separates the ring slot 1410 from the ring patch 1404 and is thus referred to herein as the “foam layer” 1416. The foam layer 1416 provides a spacer between the ring slot 1410 and the ring patch 1404, and a low dielectric constant close to air is selected to maximize the bandwidth of the scanning impedance and suppress unwanted dielectric modes. In some examples, the various dielectric layers 1412, 1422, 1426, 1444, and 1448 are printed circuit boards (PCBs). Further, the ring patch 1404 may be formed, etched, or adhered to the foam layer 1416 by the adhesive layer 1414 to hold the ring patch 1404 in place. As can be seen in more detail in FIG. 15, for example, a plurality of additional dielectric layers, including the upper lower layers 1444, 1548, and the lower lower dielectric layers 1448, 1548, provide high insulation between the antenna feed structure and the RF distribution layer.

[0071]

[0095] The conductive fence 1402 includes one or more metal (or otherwise conductive) walls. An alternative design shown in FIG. 17 replaces the metal walls with electrical vias in a circular pattern.

[0072]

[0096] More specifically, the horizontal upper section of the ring cell 1400 includes the upper dielectric layer 1412. The upper dielectric layer 1412 supports the underlying ring patch 1404 and also serves as an environmental shield against corrosion. The ring patch 1404 includes cutout holes that lower the resonance frequency of the patch and allow for a smaller outer diameter. The smaller outer diameter is desirable for reducing mutual coupling and avoiding overemphasis of the gain of the broadside antenna.

[0073]

[0097] The lower section of the ring cell 1400 collectively includes a plurality of dielectric substrate layers that support the ring slot 1410, the dual feed lines 1406 and 1408, and the thin conductive fence 1402, including the intermediate dielectric layer 1422, the lower dielectric layer 1426, the upper lower dielectric layer 1444, and the lower lower dielectric 1448. A plurality of thin adhesive layers 1424, 1442, and 1446 are sandwiched between the plurality of dielectric layers to bond the plurality of dielectric layers together. The feed lines 1406 and 1408 supply power to excite the orthogonal resonance modes within the ring slot 1410. Thereby, in turn, the orthogonal resonance modes within the upper ring patch 1404 for the RF signal are excited. When transmitting an RF signal, the feed lines supply power (voltage and current) to generate an electrical resonance within the ring slot 1410. Thereby, in turn, a desired RF signal is generated within the ring patch 1404. When receiving an RF signal, the feed lines receive the power induced into the ring slot 1410 from the ring patch 1404 that received the RF signal.

[0074]

[0098] The ring slot 1410 and the ring patch 1404 cooperate to provide a wider impedance bandwidth than either one alone could provide. Thus, the ring cell 1400 is designed to operate as a hybrid radiator that operates in both transmit and receive modes. Alternatively, the ring cell 1400 can operate in transmit mode only or receive mode only.

[0075]

[0099] The conductive fence 1402 shields the ring slot 1410 from the RF power distribution network and reduces unwanted mutual coupling with other ring slots 1410 in adjacent ring cells 1400 that are part of an array antenna (e.g., PAA). The diameter and depth of the conductive fence 1402 are set such that the ring slot 1410 resonates at or near the desired operating frequency band. In some embodiments, the openings 1428 and 1430 around the conductive fence 1402 allow the feed lines 1406 and 1408 to enter inward without being electrically shorted.

[0076]

[0100] The ring patch 1404 and the conductive fence 1402 are metallic or otherwise conductive. Electricity is supplied to the ring cell 1400 through the feed lines 1406 and 1408, and the ring fence 1402 and the ring patch 1404 are operated as radiating elements for generating a specific RF signal. As a shape, the conductive fence 1402 has a diameter larger than that of the ring slot 1410. Thereby, the ring slot 1410 can be horizontally disposed inside the conductive fence 1402. However, as can be seen in FIG. 15, in at least some embodiments, the ring slots 1410, 1510 are disposed vertically above the conductive fences 1402, 1502.

[0077]

[0101] The dual feedlines 1406, 1506, and 1408, 1508 excite the orthogonal dual linear polarization required for some applications. In other applications, dual or single circular polarization may be required. Alternatively, some embodiments include a feeding structure that uses a T-junction diplexer / combiner (transmitting / receiving respectively) and a 90-degree delay line for right-hand circular polarization, as shown in FIGS. 18A and 18B. This integrated coplanar feeding provides an economical way to achieve optimal polarization performance in the far field. Left-hand circular polarization can also be achieved by moving the L-shaped input line section from its current position to the opposite side of the V-shaped junction. To improve circular polarization performance over scanning, several other embodiments use different feeding structures that use 90-degree hybrid couplers, as shown in FIGS. 19A and 19B.

[0078]

[0102] The illustrated ring cell 1400 disclosed herein is shaped in a hexagonal pattern. However, other shapes are equally well considered. For example, the ring cell 1400 can be circular, rectangular, square, etc. In these non-hexagonal ring cells 1400, some embodiments still use a circular ring patch 1404, a ring slot 1410, and a conductive fence 1402.

[0079]

[0103] FIG. 15 shows a cut-away side view of a ring cell 1500 (identical in structure to ring cell 1400) having a conductive fence 1502 according to some of the disclosed embodiments. As shown, the ring cell includes an upper section and a lower section. The upper section includes an upper dielectric layer 1512, a ring patch 1504, an upper adhesive layer 1514, a foam layer 1516, and a lower adhesive layer 1518. The lower section includes a ring slot 1510, an upper inner metal layer 1520, an intermediate dielectric layer 1522, an upper adhesive layer 1524, a lower dielectric layer 1526, an upper-lower adhesive layer 1542, an upper-lower dielectric layer 1544, and a lower-lower dielectric layer 1548. The ring patch 1504 is disposed above the upper adhesive layer 1514 and below the dielectric layer 1512. The foam layer 1516 separates the upper adhesive layer 1514 from the ring slot 1510. Specifically, the foam layer 1516 is disposed between the upper adhesive layer 1514 and the upper inner adhesive layer 1518. The ring slot 1510 is disposed within the inner metal layer 1520. The conductive fence 1502 is disposed within the lower section of the ring cell 1500 and extends across the intermediate dielectric layer 1522, the upper adhesive layer 1524, the lower dielectric layer 1526, the upper-lower adhesive layer 1542, the upper-lower dielectric layer 1544, and the lower-lower dielectric layer 1548.

[0080]

[0104] The lower section of the ring cell 1500 also includes an asymmetric stripline 1503 and a symmetric stripline 1505. One disclosed embodiment shows a power supply line 1506 and 1508 disposed within the asymmetric stripline 1503 of the conductive fence 1502, and an RF distribution line 1507 disposed within the symmetric stripline 1505. In at least some embodiments, the symmetric stripline 1505 is embedded within the asymmetric stripline. By embedding the symmetric stripline 1505 including the RF distribution line 1507 within the asymmetric stripline 1503, high isolation between the antenna power supply and the distribution network is obtained. In at least some embodiments, by embedding the symmetric stripline 1505 including the RF distribution line 1507 (i.e., the RF distribution layer or the RF distribution network) within the asymmetric stripline 1503 (i.e., the antenna power supply structure), the isolation can be increased by up to 30 dB without adding any additional physical thickness to the PCB. The isolation is increased due to physically separating the antenna power supply and the distribution network in the z-direction and adding a ground layer between the structures to prevent coupling. As a result, the high isolation between the antenna power supply structure and the RF distribution layer enables the antenna element to be used in higher gain and higher output arrays. For example, FIGS. 20 and 23 below show unit cells 2000, 2300 including a symmetric stripline having an RF distribution line embedded within the asymmetric stripline.

[0081]

[0105] FIG. 16 shows a top view of an antenna array 1600 fabricated with a plurality of ring cells 1600a - d according to some of the disclosed embodiments. In at least some embodiments, the antenna array 1600 includes ring cells 1600a - d that are structurally identical to ring cells 1400 and 1500. This figure shows an example of the feed lines 1606a - d and 1608a - d of the various ring cells 1600a - d having a 90 - degree rotation. In other words, the feed lines 1606a and 1608a are rotated 90 degrees from the positions of the feed lines 1606b and 1608b. This arrangement suppresses the unwanted cross - polarized signal levels in the far field.

[0082]

[0106] Alternative designs that do not use the conductive fences 1402, 1502 are shown in FIGS. 17 - 19B. As shown in FIGS. 14 - 15, instead of the conductive fences 1402, 1502, these alternative embodiments form a circular fence using an assembly of electrical vias.

[0083]

[0107] In accordance with these concepts, FIG. 17 shows a perspective view of a ring cell 1700 having a circular via fence 1702 according to some of the disclosed embodiments. The ring cell 1700 includes a ring patch 1704, two feed lines 1706 and 1708, a ring slot 1710, an upper dielectric layer 1712, an upper adhesive layer 1714, a foam layer 1716, an upper inner adhesive layer 1718, an inner metal layer 1720, an intermediate dielectric layer 1722, a lower dielectric layer 1726, an upper lower dielectric layer 1744, and a lower lower dielectric layer 1448. Similar to the ring cells 1400, 1500, a plurality of adhesive layers (not shown here) are sandwiched between the plurality of dielectric layers to bond the plurality of dielectric layers together. These various components are arranged in the same manner as described above with respect to the ring cells 1400, 1500. However, instead of the conductive fence 1402, the ring cell 1700 includes electrical vias 1702a - n. The electrical vias 1702a - n are arranged in a circular pattern around the ring slot 1710 and collectively form a via fence having a number of openings 1730 - 1736 (only 4 are labeled).

[0084]

[0108] Similar to the ring cells 1400 and 1500, the horizontal upper section of the ring cell 1700 includes an upper dielectric layer 1712. The upper dielectric layer 1712 supports the underlying ring patch 1704 and also serves as an environmental shield against corrosion. The ring patch 1704 includes cutout holes that lower the resonance frequency of the patch and allow for a smaller outer diameter. The smaller outer diameter is desirable for reducing mutual coupling and avoiding overemphasis of the gain of the broadside antenna.

[0085]

[0109] The lower section of the ring cell 1700 collectively includes a plurality of dielectric substrate layers including an intermediate dielectric layer 1722, a lower dielectric layer 1726, an upper lower dielectric layer 1744, and a lower lower dielectric layer 1748 that support a via fence formed by the ring slot 1710, the dual feed lines 1706 and 1708, and the conductive vias 1702a - n. A plurality of thin adhesive layers (not shown here) are sandwiched between the plurality of dielectric layers to bond the plurality of dielectric layers together. The feed lines 1706 and 1708 supply power to excite the orthogonal resonance modes within the ring slot 1710. This, in turn, then excites the orthogonal resonance modes within the upper ring patch 1704 for the RF signal. When transmitting an RF signal, the feed lines supply power (voltage and current) to generate an electrical resonance within the ring 1710. This, in turn, then generates the desired RF signal within the ring patch 1704. When receiving an RF signal, the feed lines receive the power induced into the ring 1710 from the ring patch 1704 that received the RF signal.

[0086]

[0110] The ring patch 1704 and the electrical vias 1702a - n are metallic or otherwise conductive. Electricity is supplied to the ring cell 1700 through the feed lines 1706 and 1708, and the electrical vias 1702a - n and the ring patch 1704 are operated as radiating elements for generating a specific RF signal. As a shape, the via fence has a diameter larger than that of the ring slot 1710. Thereby, the ring slot 1710 can be horizontally disposed inside the conductive fence 1702.

[0087]

[0111] The via fence created by the electrical vias 1702a - n also shields the ring slot 1710 from the power distribution network and reduces undesirable mutual coupling with other ring slots 1710 in adjacent ring cells 1700 that are part of an array antenna (e.g., PAA). The diameter and depth of the via fence are set such that the ring slot 1710 resonates at or near the desired operating frequency band. In some embodiments, the openings around the conductive fence 1702 allow the feed lines 1706 and 1708 to enter inward without being electrically short - circuited. The feed lines 1706 and 1708 are disposed within the upper half in the vertical direction of the electrical vias 1702a - n. Except for the features related to the conductive fence 1702 outlined above, the ring cell 1700 is structurally and operationally substantially the same as the ring cells 1400, 1500.

[0088]

[0112] Figures 18A and 18B respectively show a perspective view and a top view of ring cells 1400, 1500 having a T-junction delay feeder line 1801 according to some of the disclosed embodiments. The T-junction delay feeder line 1801 includes two feeder lines (a shorter feeder line 1802 and a longer L-shaped feeder line 1804). The two feeder lines extend from a single input / output (I / O) line 1806. In circular polarization formation in RF signals transmitted or received through the ring cell 1800, the feeder line 1804 is longer than the feeder line 1802. These separate feeder lines 1802 and 1804 are arranged at 90 degrees to each other. Although a ring cell 1800 having electrical vias (such as electrical vias 1702a - n) is shown, the T-junction delay feeder line 1801 can also be used in ring cells 1400, 1500 having conductive fences 1402, 1502.

[0089]

[0113] The illustrated T-junction delay feeder line 1801 provides a right-handed circular polarization and supplies an optimal polarization in the far field. A left-handed circular polarization can also be achieved by moving the longer L-shaped feeder line 1804 from the illustrated position to the other side of the V-shaped junction.

[0090]

[0114] The illustrated T-junction delay feeder line 1801 can also be used in ring cells 1400, 1500 instead of the illustrated ring cell 1700. The ring cell 1800 is shown only in FIGS. 18A - 18B as an example of a ring cell having a T-junction delay feeder line 1801.

[0091]

[0115] FIGS. 19A and 19B respectively show a perspective view and a top view of a ring cell 1900 having a 90-degree hybrid coupler 1901 according to some of the disclosed embodiments. The hybrid coupler 1901 includes two feed lines 1902 and 1904 and an elliptical (or circular) path line 1906. In some embodiments, the feed lines 1902 and 1904 are arranged at 90 degrees to each other. The hybrid coupler 1901 includes two terminals 1908 and 1910. Terminal 1908 acts as an input or output of voltage depending on whether the ring cell transmits or receives an RF signal. Terminal 1910 is connected to an electrical via 1912. The electrical via 1912 penetrates the lower dielectric layer 1926 and is electrically coupled to a resistor 1914. During operation, this hybrid coupler 1901 improves the circular polarization performance.

[0092]

[0116] The illustrated hybrid coupler 1901 can also be used in the ring cell 1800 instead of the illustrated ring cell 1900. The ring cell 1900 is shown only in FIGS. 19A-19B as an example of a ring cell having a hybrid coupler 1901.

[0093]

[0117] FIG. 20 shows an example of an antenna array according to some of the disclosed embodiments. The antenna array 2000 shows an example of a symmetric stripline 2005 as described above with respect to FIG. 15. In at least some embodiments, the symmetric stripline 2005 includes an embedded asymmetric stripline having an RF distribution line within the symmetric stripline.

[0094]

[0118] In at least some embodiments, the disclosed ring cell can be configured within the array to operate with the aircraft 800 in a manner similar to the ring cell 100 as disclosed above with respect to FIG. 8.

[0095]

[0119] FIG. 21 shows a block diagram of an example of an antenna system 2100 for an antenna array 2102 fabricated with ring cells 1600a - n of the present disclosure. In this example, the antenna system 2100 includes a power supply 2104, a controller 2106, and an antenna array 2102. In this example, the antenna array 2102 is a phased array antenna (“PAA”) that includes a plurality of ring cells 1600a - n that operate as either a transmitting and / or receiving module. The ring cells 1600a - n include corresponding radiating elements. The corresponding radiating elements can be combined to transmit and / or receive RF signals. For example, the ring cells 100a - n can be configured to operate within a K - band frequency range (e.g., from about 20 GHz to 40 GHz for the NATO K - band, and from 18 GHz to 26.5 GHz for the IEEE K - band).

[0096]

[0120] The power supply 2104 is a device, component, and / or module that provides power to the controller 2106 within the antenna system 2100. The controller 2106 is a device, component, and / or module that controls the operation of the antenna array 2102. The controller 2106 can be a processor, microprocessor, microcontroller, digital signal processor (“DSP”), or other type of device that can be programmed with either hardware and / or software. The controller 2106 controls the power feed provided to the antenna array 2102, including, but not limited to, calibrating a specific polarization, voltage, frequency, etc. of the power feed. For clarity, only one line is shown between the controller 2106 and the antenna array 2102, but in reality, several electrical connections and supply lines can connect the controller 2106 to the antenna array 2102.

[0097]

[0121] In some embodiments, the controller 2106 performs a specific power feed to the various ring cells 1600a - n to generate a number of RF signals that are combined either constructively or destructively to form a desired cumulative RF signal for transmission.

[0098]

[0122] The RF signals emitted from each of the ring cells 1600a - n within the array antenna 2102 may be in - phase to generate constructive strong radiation, or may have a phase shift to generate destructive specific RF signals. The direction can be controlled by setting the phase shift between the signals transmitted to different ring cells 1600a - n. The phase shift can be controlled by the controller 2106 by placing a small time delay between the signals transmitted to consecutive ring cells 1600a - n within the array.

[0099]

[0123] The antenna system 2100 is described as communicating signals with each other. In that case, signal communication refers to any kind of communication and / or connection between circuits, components, modules, and / or devices that enables a circuit, component, module, and / or device to transmit and receive signals and / or information between another circuit, component, module, and / or device. The communication and / or connection may be along any signal path between circuits, components, modules, and / or devices that enables a signal and / or information to be transmitted from one circuit, component, module, and / or device to another, and this includes wireless or wired signal paths. The signal path may be physical, such as, for example, a conductor, an electromagnetic waveguide, a cable, attached and / or electromagnetically or mechanically coupled terminals, a semiconductor, or a dielectric material or device, or other similar physical connections or couplings. Further, the signal path may be a non - physical path. A non - physical path is, for example, a free space (in the case of electromagnetic propagation) or an information path through digital components, where the communication information is transmitted in various digital forms from one circuit, component, module, and / or device to another without passing through a direct electromagnetic connection.

[0100]

[0124] This antenna system 2100 provides means for transmitting (or receiving) RF signals to (or from) airborne / mobile vehicles with agile electronically scanned antenna array beams without mechanical moving parts. The antenna system 2100 can be used in communication systems and other applications, including but not limited to radar / sensors, electronic warfare, military applications, mobile communications, etc. The antenna system 2100 provides a high-performance, lightweight, thin, and cost-effective solution to meet difficult and evolving mission requirements.

[0101]

[0125] FIG. 22 shows an AIPWB 2200 for an antenna array 2102 constructed of several ring cells 1600a - n according to some of the disclosed embodiments. The AIPWB 2200 includes nine vias (1 - 9) and various laminations (1, 2, 3), one of which is split into two separate sub-laminations (1A and 1B). Sub-lamination 1A includes layers 1 to 6 and provides control and power wiring for the MMIC using a single drill step and the RF interconnect of layer 1. Sub-lamination 1B covers layers 7 to 11 and is an RF asymmetric stripline. The RF asymmetric stripline provides RF distribution across the antenna array 2102 to the quad (or other multiplier) element beamforming MMIC and provides a feeding structure to the aperture-coupled patch. Sub-lamination 1B has one drill step for RF suppression vias used for insulation between the radiating structure and the RF distribution network. Lamination 2 can have coast-to-coast layer 1 to layer 11 vias implemented as shown in FIG. 22. Alternatively, as shown in FIG. 10, the electrical junctions of sub-laminations 1A and 1B can be realized with an Ormet paste process. Lamination 3 connects the entire PCB structure with foam spacers (e.g., foam layers 1416, 1516) and an electrically insulated radiating patch on layer 12.

[0102]

[0126] FIG. 23 shows a partial view of an antenna array 2300 fabricated with ring cells 1600a - n disclosed in the present disclosure. Shown are elements of layers 8 through 10, including the distribution network 2302 of layer 8, the GND 2304 of layer 9 removed around the antenna feed to maintain an asymmetric stripline between the GNDs of layers 7 and 11, and the antenna feed 2306 of layer 10.

[0103]

[0127] In at least some embodiments, the disclosed ring cells can be configured within a sub - array antenna of a conventional 16 - ring array that, in accordance with some embodiments, uses a beamformer and a front - end integrated circuit (IC), as disclosed above with respect to FIG. 11.

[0104]

[0128] FIG. 24 shows a method for providing a unit cell antenna for a periodic antenna array according to some of the disclosed embodiments. In at least some embodiments, method 2400 can be used to provide a unit cell (e.g., ring cells 1400, 1500) as described above with respect to FIGS. 14-23. Method 2400 includes, at 2410, providing an upper section (e.g., the upper section of FIG. 15) for communicating a radio frequency (RF) signal. In at least some embodiments, the upper section includes a dielectric layer (e.g., dielectric layers 1412, 1512) and a ring patch (e.g., ring patches 1404, 1504). The ring patch is supported by the dielectric layer and has a central cutout hole to lower the resonant frequency of the ring patch. Method 2400 includes, at 2420, providing a lower section (e.g., the lower section of FIG. 15) for generating a desired radio frequency (RF) signal. In at least some embodiments, the lower section includes a plurality of dielectric layers (e.g., dielectric layers 1422, 1426, 1448, 1522, 1526, 1548), a ring slot (e.g., ring slots 1410, 1510), a conductive fence (e.g., ring fence or conductive fence 1402, 1502), and two feed lines (e.g., feed lines 1406, 1408, 1506, 1508). In at least some embodiments, the ring slot is supported by one of the plurality of dielectric layers. The conductive fence substantially surrounds the ring slot. The two feed lines are 90 degrees out of phase. Method 2400 includes, at 2430, providing a foam layer (e.g., foam layers 1416, 1516) disposed between the upper section and the lower section. In at least some embodiments, the foam layer separates the ring patch from the ring slot. The method 2400 and configuration outlined herein provide high insulation between the upper section and the lower section, enabling the antenna element to be used in higher gain and higher output arrays without adverse feedback problems.

[0105]

[0129] FIG. 25 shows a method of manufacturing a unit cell antenna system for a periodic antenna array according to some of the disclosed embodiments. In at least some embodiments, method 2500 can be used to fabricate, manufacture, and / or assemble a unit cell antenna system (e.g., ring cells 1400, 1500) for a periodic antenna array (e.g., antenna array 1600) as described above with respect to FIGS. 14-23. As disclosed herein, the steps, operations, processes, procedures, and / or processes of manufacturing and / or assembling a unit cell antenna system substantially coincide with the steps, operations, processes, procedures, and / or processes known to those skilled in the art of fabrication, manufacturing, and assembly. The manufacturing method 2500 includes, at 2510, forming an upper section (e.g., the upper section of FIG. 15) for communicating a radio frequency (RF) signal. In at least some embodiments, the upper section is formed to include a dielectric layer (e.g., dielectric layers 1412, 1512) and a ring patch (e.g., ring patches 1404, 1504). The ring patch is supported by the dielectric layer and is formed to have a central cutout hole to lower the resonance frequency of the ring patch. The manufacturing method 2500 includes, at 2520, forming a lower section (e.g., the lower section of FIG. 15) for generating a desired radio frequency (RF) signal. In at least some embodiments, the lower section is formed to include a plurality of dielectric layers (e.g., dielectric layers 1422, 1426, 1448, 1522, 1526, 1548), a ring slot (e.g., ring slots 1410, 1510), a conductive fence (e.g., ring fence or conductive fence 1402, 1502), and two feed lines (e.g., feed lines 1406, 1408, 1506, 1508). In at least some embodiments, the ring slot is formed to be supported by one of the plurality of dielectric layers. The conductive fence is formed to substantially surround the ring slot. The two feed lines are formed to have a 90-degree phase shift.Manufacturing method 2500 includes, at 2530, forming a foam layer (e.g., foam layers 1416, 1516) to be disposed between an upper section and a lower section. In at least some embodiments, the foam layer is formed to separate a ring patch from a ring slot. The method 2500 and configuration outlined herein provide high insulation between the upper section and the lower section, enabling the antenna element to be used with higher gain and higher output arrays without adverse feedback problems.

[0106]

[0130] Further Notes and Examples

[0107]

[0131] Example 1 includes a unit cell antenna system for a periodic antenna array. The system includes an upper section for communicating a radio frequency (RF) signal, the upper section including a dielectric layer and a ring patch, the ring patch being supported by the dielectric layer and having a central cutout hole for reducing the resonant frequency of the ring patch; a lower section for generating a desired radio frequency (RF) signal, the lower section including a plurality of dielectric layers, a ring slot supported by one of the plurality of dielectric layers, a conductive fence substantially surrounding the ring slot, and two feed lines with a 90-degree phase shift between them; and a foam layer disposed between the upper section and the lower section, the foam layer for separating the ring patch from the ring slot.

[0108]

[0132] Example 2 includes the system of Example 1. In that case, the lower section further includes an RF distribution layer of a symmetric strip line embedded in an asymmetric strip line of the lower section, the RF distribution layer of the embedded symmetric strip line providing high signal insulation due to the physical separation between the upper section and the lower section.

[0109]

[0133] Example 3 includes the system of Example 1. In that case, when in the transmission mode, the power supply line couples energy to the ring slot, and the ring slot generates a desired RF signal within the ring patch.

[0110]

[0134] Example 4 includes the system of Example 1. In that case, when in the reception mode, the ring patch generates an electrical resonance within the ring slot, and the ring slot couples energy to the power supply line.

[0111]

[0135] Example 5 includes the system of Example 1. In that case, the conductive fence shields the ring slot from the RF power distribution network and reduces unwanted mutual coupling with other ring slots in adjacent ring cells that are part of the array antenna.

[0112]

[0136] Example 6 includes the system of Example 5. In that case, the conductive fence comprises one or more metal walls.

[0113]

[0137] Example 7 includes the system of Example 5. In that case, the conductive fence comprises electrical vias in a circular pattern.

[0114]

[0138] Example 8 includes the system of Example 1. In that case, the power supply line includes a T-junction delay for power supply.

[0115]

[0139] Example 9 includes the system of Example 1. In that case, the power supply line includes a hybrid coupler for power supply.

[0116]

[0140] Example 10 includes a method for providing a unit cell antenna for a periodic antenna array. The method includes an upper section for communicating a radio frequency (RF) signal, the upper section including a dielectric layer and a ring patch, the ring patch being supported by the dielectric layer and having a central cutout hole for reducing the resonance frequency of the ring patch, providing the upper section, a lower section for generating a desired radio frequency (RF) signal, the lower section including a plurality of dielectric layers, a ring slot supported by one of the plurality of dielectric layers, a conductive fence substantially surrounding the ring slot, and two feed lines, the feed lines being 90 degrees out of phase, providing the lower section including the two feed lines, and a foam layer disposed between the upper section and the lower section, providing the foam layer for separating the ring patch from the ring slot.

[0117]

[0141] Example 11 includes the method of Example 10. In that case, the lower section further includes an RF distribution layer of a symmetric strip line embedded in an asymmetric strip line of the lower section, and the RF distribution layer of the embedded symmetric strip line provides high signal insulation due to the physical separation between the upper section and the lower section.

[0118]

[0142] Example 12 includes the method of Example 10. In that case, when in the transmit mode, the feed lines couple energy to the ring slot, and the ring slot generates a desired RF signal within the ring patch.

[0119]

[0143] Example 13 includes the method of Example 10. In that case, when in the receive mode, the ring patch generates an electrical resonance within the ring slot, and the ring slot couples energy to the feed lines.

[0120]

[0144] Example 14 includes the method of Example 10. In that case, the conductive fence shields the ring slot from the RF power distribution network and reduces unwanted mutual coupling with other ring slots in adjacent ring cells that are part of the array antenna.

[0121]

[0145] Example 15 includes the method of Example 14. In that case, the conductive fence comprises one or more metal walls.

[0122]

[0146] Example 16 includes the method of Example 14. In that case, the conductive fence comprises electrical vias in a circular pattern.

[0123]

[0147] Example 17 includes the method of Example 10. In that case, the ring patch is disposed under the dielectric layer and above the foam layer.

[0124]

[0148] Example 18 includes the method of Example 10. In that case, the feed line includes a T-junction delay for feeding.

[0125]

[0149] Example 19 includes a method of manufacturing a unit cell antenna system for a periodic antenna array. The method includes forming an upper section for communicating a radio frequency (RF) signal, the upper section including a dielectric layer and a ring patch, the ring patch being supported by the dielectric layer and having a central cutout hole for reducing the resonant frequency of the ring patch; forming a lower section for generating a desired radio frequency (RF) signal, the lower section including a plurality of dielectric layers, a ring slot supported by one of the plurality of dielectric layers, a conductive fence substantially surrounding the ring slot, and two feed lines having a 90-degree phase shift; and forming a foam layer disposed between the upper section and the lower section for separating the ring patch from the ring slot.

[0126]

[0150] Example 20 includes the method of Example 19. In that case, the lower section further includes an RF distribution layer of a symmetric stripline embedded in the asymmetric stripline of the lower section, and the RF distribution layer of the embedded symmetric stripline provides high signal insulation due to the physical separation between the upper section and the lower section.

[0127]

[0151] Although the subject matter has been described in language specific to structural features and / or methodological acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as exemplary forms of implementing the claims.

[0128]

[0152] It will be understood that the benefits and advantages described above may be associated with one embodiment or may be associated with several embodiments. A plurality of embodiments are not limited to those that solve any or all of the stated problems or have any or all of the stated benefits and advantages. It will further be understood that references to "one" item can represent one or more of such items.

[0129]

[0153] As used in this disclosure, the term "comprising" is used to mean including the recited feature(s) or act(s) (without excluding the existence of one or more additional features or acts).

[0130]

[0154] In some examples, the steps shown in the drawings may be implemented in hardware programmed or designed to perform the operations as software instructions encoded on a computer-readable medium, or in both. For example, aspects of the present disclosure may be implemented as an ASIC, an SoC, or other circuitry including a plurality of interconnected conductive elements.

[0131]

[0155] The order of execution or implementation of operations in the embodiments of the present disclosure shown and described in this specification is not essential unless otherwise specified. That is, the operations can be executed in any order unless otherwise specified, and the embodiments of the present disclosure may include additional operations or fewer operations than those disclosed in this specification. For example, it is considered to be within the scope of the aspects of the present disclosure to execute or implement a particular operation before, simultaneously with, or after another operation.

[0132]

[0156] When introducing elements or examples thereof of multiple aspects of the present disclosure, the articles "a, an" and "the, said" are intended to mean that one or more of such elements are present. The terms "comprising," "including," and "having" are intended to be inclusive and mean that additional elements other than the recited elements may exist. The term "exemplary" is intended to mean "an example of." The phrase "one or more of A, B, and C" means "at least one of A and / or at least one of B and / or at least one of C."

[0133]

[0157] Although the aspects of the present disclosure have been described in detail, it will be apparent that modifications and changes can be made without departing from the scope of the aspects of the present disclosure defined in the appended claims. Since various changes can be made to the above structures, products, and methods without departing from the scope of the multiple aspects of the present disclosure, all matters included in the above description and illustrated in the accompanying drawings are intended to be construed as illustrative and not in a limiting sense.

[0134]

[0158] It should be understood that the above description is intended to be illustrative and not restrictive. By way of example, the above-described embodiments (and / or aspects thereof) may be used in combination with each other. Further, without departing from the scope of the various embodiments of the present disclosure, numerous modifications may be made to the teachings of the various embodiments of the present disclosure to adapt to a particular situation or material. The shapes, dimensions, and types of materials described herein are intended to define the parameters of the various embodiments of the present disclosure, but these embodiments are exemplary rather than limiting. Many other embodiments will be apparent to those skilled in the art upon review of the above description. The scope of the various embodiments of the present disclosure should be determined with reference to the appended claims, as well as the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in which" are used as plain synonyms for the terms "comprising" and "wherein," respectively. Further, the limitations in the following claims are not recited in means-plus-function format and are not intended to be construed under 35 U.S.C. § 112, ¶ 6, unless such claim limitations expressly use the recitation "means for" followed by a recitation of a function without further structure.

[0135]

[0159] The description provided herein discloses various embodiments of the present disclosure, including the best mode, and uses examples to enable those skilled in the art to practice the various embodiments of the present disclosure, including the creation and use of any device or system and the performance of any incorporated method. The patentable scope of the various embodiments of the present disclosure is defined by the claims and includes other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that differ only insubstantially from the literal language of the claims.

[0136]

[0160] Although the present disclosure has been described with reference to various embodiments, various changes and modifications can be made without departing from the scope of the present disclosure.

Claims

1. A unit cell antenna system (1400, 1500) for a periodic antenna array (1600), comprising: an upper section for communicating a radio frequency (RF) signal, said upper section comprising: a dielectric layer (1412, 1512), and a ring patch (1404, 1504), said ring patch being supported by said dielectric layer and having a central cutout hole for reducing the resonant frequency of said ring patch, the upper section; a lower section for generating a desired radio frequency (RF) signal, said lower section comprising: a plurality of dielectric layers (1422, 1426, 1444, 1448, 1522, 1526, 1544, 1548), a ring slot (1410, 1510) supported by one of said plurality of dielectric layers, a conductive fence (1402, 1502) substantially surrounding said ring slot, two feeding lines (1406, 1408, 1506, 1508), said feeding lines having a 90-degree phase shift, the lower section including two feeding lines, and a foam layer (1416, 1516) disposed between said upper section and said lower section, said foam layer for separating said ring patch from said ring slot.

2. The lower section further includes an RF distribution layer (1507) of a symmetric strip line embedded in an asymmetric strip line (1505) of the lower section, and said embedded RF distribution layer of the symmetric strip line provides high signal insulation due to physical separation between said upper section and said lower section. The system according to claim 1.

3. When in transmission mode, said feeding lines (1406, 1408, 1506, 1508) couple energy to said ring slots (1410, 1510), and said ring slots generate a desired RF signal in said ring patch. The system according to claim 1.

4. When in reception mode, said ring patches (1404, 1504) generate an electrical resonance in said ring slots, and said ring slots couple energy to said feeding lines. The system according to claim 1.

5. The conductive fences (1402, 1502) shield the ring slots (1410, 1510) from an RF power distribution network and reduce unwanted mutual coupling with other ring slots in adjacent ring cells (1600a - d) that are part of the array antenna (1600), the system of claim 1. **Claim 6** The conductive fences (1402, 1502) comprise one or more metal walls, the system of claim 5. **Claim 7** The conductive fences (1402, 1502) comprise circular - pattern electrical vias (1702a - n), the system of claim 5. **Claim 8** The feed lines (1802, 1804) include a T - junction delay (1801) for feeding power, the system of claim 1. **Claim 9** The feed lines (1902, 1904) include a hybrid coupler (1901) for feeding power, the system of claim 1. **Claim 10** A method (2400) for providing unit - cell antennas (1400, 1500) for a periodic antenna array (1600), providing (2410) an upper section for communicating a radio - frequency (RF) signal, the upper section comprising a dielectric layer (1412, 1512), and a ring patch (1404, 1504), the ring patch being supported by the dielectric layer and having a central cut - out hole for reducing the resonant frequency of the ring patch, providing the upper section, providing (2420) a lower section for generating a desired radio - frequency (RF) signal, the lower section comprising a plurality of dielectric layers (1422, 1426, 1444, 1448, 1522, 1526, 1544, 1548), a ring slot (1410, 1510) supported by one of the plurality of dielectric layers, a conductive fence (1402, 1502) substantially surrounding the ring slot, two feed lines (1406, 1408, 1506, 1508), the feed lines having a 90 - degree phase shift, including providing the lower section, and providing (2430) a foam layer (1416, 1516) disposed between the upper section and the lower section, including providing a foam layer for separating the ring patch from the ring slot. **Claim 11** The lower section further includes an RF distribution layer (1507) of a symmetric stripline embedded within an asymmetric stripline (1505) of the lower section, and the RF distribution layer of the embedded symmetric stripline provides high signal insulation resulting from physical separation of the upper section and the lower section. The method according to claim 10.

12. When in the transmission mode, the feeding lines (1406, 1408, 1506, 1508) couple energy to the ring slots (1410, 1510), and the ring slots generate a desired RF signal within the ring patch. The method according to claim 10.

13. When in the reception mode, the ring patches (1404, 1504) generate an electrical resonance within the ring slots, and the ring slots couple energy to the feeding lines. The method according to claim 10.

14. The conductive fences (1402, 1502) shield the ring slots (1410, 1510) from an RF power distribution network and reduce undesired mutual coupling with other ring slots in adjacent ring cells (1600a - d) that are part of the array antenna (1600). The method according to claim 10.

15. The conductive fence (1402, 1502) comprises one or more metal walls. The method according to claim 14.

16. The conductive fence (1402, 1502) comprises electrical vias (1702a - n) in a circular pattern. The method according to claim 14.

17. The ring patches (1404, 1504) are disposed below the dielectric layer (1412, 1512) and above the foam layer (1416, 1516). The method according to claim 10.

18. The feeding lines (1406, 1408, 1506, 1508) include a T - junction delay (1801) for feeding. The method according to claim 10.

19. A method (2500) of manufacturing a unit cell antenna system (1400, 1500) for a periodic antenna array (1600), comprising: Forming (2510) an upper section for communicating a radio frequency (RF) signal, the upper section comprising: A dielectric layer (1412, 1512), and Forming an upper section that includes ring patches (1404, 1504), the ring patches being supported by the dielectric layer and having a central cutout hole for reducing the resonance frequency of the ring patches. Forming a lower section (2520) for generating a desired radio frequency (RF) signal, the lower section including a plurality of dielectric layers (1422, 1426, 1444, 1448, 1522, 1526, 1544, 1548), ring slots (1410, 1510) supported by one of the plurality of dielectric layers, conductive fences (1402, 1502) substantially surrounding the ring slots, forming a lower section that includes two feed lines (1406, 1408, 1506, 1508), the feed lines having a 90-degree phase shift, and forming a foam layer (1416, 1516) disposed between the upper section and the lower section (2530), including forming a foam layer for separating the ring patches from the ring slots. Claim 20 The method according to claim 19, wherein the lower section further includes an RF distribution layer of a symmetric stripline embedded in an asymmetric stripline (1505) of the lower section, and the RF distribution layer of the embedded symmetric stripline provides high signal insulation due to the physical separation between the upper section and the lower section.

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