WO2019058378A1

WO2019058378A1 - Dual band planar antenna

Info

Publication number: WO2019058378A1
Application number: PCT/IL2018/051059
Authority: WO
Inventors: Heylal MASHAAL
Original assignee: Mashaal Heylal
Priority date: 2017-09-19
Filing date: 2018-09-18
Publication date: 2019-03-28

Abstract

A highly performing dual-band and broad-band planar antenna can replace conventional feed horn technology as feed antennas for reflector systems. Embodiments allow custom electronically selectable polarization: linear or circular polarization in both bands independently by controlling the amplitude and phase stimulation of four feed probes for each band. Full integration of the antenna and RF frontend can be on the same printed circuit board or chip. Embodiments alleviate the need for specialized polarizers and orthomode transducers for operation in circular polarization and two bands. The planar antenna has low footprint and weight as compared to traditional horn antennas and facilitates greater flexibility in design and can be produced with standard low-cost PCB production processes and materials. Performance comparable to traditional horn technology can be achieved, such as extremely rotationallv symmetric beam thus suitable for efficient reflector illumination together with extremely low cross polarization performance.

Description

DUAL BAND PLANAR ANTENNA

Field of the Invention

The present invention relates to antennas, and in particular it concerns a dual band planar antenna.

Background of the Invention

The satellite communication market is developing rapidly with the

introduction of high throughput satellites in the relatively newly used Ka (27.5-30 GHz) and K (17.7-20.2 GHz) frequency bands. This opens the door for a wide use of two-way (bi-directional) broadband data services, for example, to homes and small businesses. A two-way system operates at two different frequency bands, the uplink channel from the user to the satellite, typically at Ka band, and the downlink channel from the satellite to user, typically at K band. The use of separate communication bands facilitates full-duplex communication. At the same time, it is likely that in the coming years, the existing generation of satellites, operating in Ku band (13.75-14.5 GHz) uplink channel and X band (10.75-12.75 GHz) downlink channel, will continue to be of wide service and co-exist with the new generation of satellites. It is therefore desirable to develop antenna systems that can operate in two or more pairs of frequency bands to allow two-way communications in Ka-K or Ku-X bands, for example, or working with two generations of collocated satellites operating simultaneously in K and X bands for example.

In satellite communications, systems with dish-type antennas are commonly used for collecting and directing the radiated signals. These systems typically include one or more feed horns situated in the focal plane of the dish. Horn technology is traditionally preferred as a feed system due to horn technology's ability to provide high performance, such as broadband operation, high efficiency, and low levels of undesired emitted radiation e.g. side lobes and cross polarization. However, dual band feed horns have several limitations, such as large footprints, usually optimal in one band only, complicated and relatively costly to make, require a specialized waveguide feed network and polarizer/orthomode transducer, and are hard to integrate with the RF frontend.

Advances in printed antenna technology and the new availability of chip scale integrated RF frontend components for the satellite frequency bands, mainly driven by the development of phased array antennas and the 5^th generation of cellular networks (5G), motivate the use of printed antennas as feeds for dish-type antenna systems. Printed antenna technology has advantages over conventional antennas of lower manufacturing costs, standard printed circuit board technology, low volume, low weight, easier and faster proto-typing and easier integration with RF frontend and additional circuitry. To date, there are no successful printed antenna solutions that can rival the performance of horn technology as feeds for reflector antenna systems for two-way communications in terms of bandwidthe, beam symmetry and low levels of cross-polarization.

Summary of the Invention

The present invention is a highly performing dual-band and broad-band planar antenna that can replace conventional feed horn technology as feed antennas for reflector systems. Embodiments allow custom electronically selectable

polarization: linear or circular polarization in both bands independently by controlling the amplitude and phase stimulation of four feed probes for each band. Pull integration of the antenna and RF frontend can be on the same printed circuit board or chip. Embodiments alleviate the need for specialized polarizers and orthomode transducers for operation in circular polarization and two bands. The planar antenna has low footprint and weight as compared to traditional horn antennas, allowing greater flexibility in design and can be produced with standard low-cost PCB production processes and materials. Performance comparable to traditional horn technology can be achieved, such as extremely rotationally symmetric beam thus suitable for efficient reflector illumination together with extremely low cross polarization performance.

According to the teachings of the present embodiment there is provided a planar antenna including:

a ground plane,

a first patch antenna mounted in spaced relation to the ground plane and radiating towards a zenith normal to the ground plane in a first frequency band,

a second patch antenna generally concentric with the first patch antenna and radiating towards the zenith in a second frequency band, the second frequency band other than the first frequency band, a first feed arrangement including a first set of two or more feed probes, the first feed arrangement feeding a first signal to the first patch antenna, and

a second feed arrangement including a second set of two or more feed probes, the second feed arrangement feeding a second signal to the second patch antenna,

wherein each the set of feed probes is respectively disposed at angular intervals with respect to an axis extending through a concentric center of the first and second patch antenna elements.

In an optional embodiment, a radius of the first patch antenna is smaller than a radius of the second patch antenna, and the first frequency band is higher than the second frequency band. In another optional embodiment, a shape of the first and second patch antennas is selected from the group consisting of: the same shape, different shapes, different annular shapes, annular, circular rings, a central patch and a surrounding annular shape. In another optional embodiment, the first and second patch antennas are disposed in a layer of the planar antenna selected from the group consisting of: the same layer, different layers, and different layers separated by a third dielectric layer. In another optional embodiment, the first frequency band and the second frequency band are respectively selected from the group consisting of: the Ka band and the K band, the K band and the Ku band, the K-band and the X-band, the Ku-band and the X-band, the WIFI bands, the L-bands for GPS communication, and a ratio of a center frequency of the high band to a center frequency of the low band is in a range from 1.3 to 2. In another optional embodiment, the angular intervals are equally spaced.

In another optional embodiment, the first set and second set of feed probes each include four feed probes. In another optional embodiment, each of the feed probes is connected to a conductive element, each the conductive element extending through, and insulated from, the ground plane. In another optional embodiment, the feed probes are separated from the patch antennas by a second dielectric layer. In another optional embodiment, the first set of feed probes is operationally connected to a high or bandpass filter, and the second set of feed probes is operationally connected to a low or bandpass filter. In another optional

embodiment, the first set and second set of feed probes each connect to respective RF chains, each RF chain for transmitting and receiving signals via respective first and second patch antennas.

In another optional embodiment, further including: a conductive fence:

disposed circumferentially surrounding the first and second patch antennas, surrounding the first and second feed arrangements, and electrically connected to the ground plane. In another optional embodiment, the conductive fence has a radius less than 1/2 of a wavelength of the first frequency band. In another optional embodiment, further including; a choke enclosure: disposed circumferentially surrounding the first and second patch antennas, and electrically connected to the ground plane. In another optional embodiment, a height of the choke enclosure is less than1/4 wavelength of an intermediate frequency, and a width of the choke enclosure is less than ½ wavelength of the intermediate frequency, the intermediate frequency being a frequency lower than the first frequency band and higher than the second frequency band, and the width being a gap distance between: an inner radius of the conductive fence, and an outer radius of conducting elements, the conducting elements disposed circumferentially surrounding the conductive fence, and electrically connected to the ground plane. In another optional embodiment, the conductive fence and the conducting elements are made of vertical conducting elements that connect the ground plane and a second conducting layer.

In another optional embodiment, the first and second patch antennas radiate with respective first and second beams, each of the beams is one of linearly, circularly or elliptically polarized, a polarization of each of the beams being independently controlled by an amplitude and phase of the first and second signals provided by the first and second feed arrangements.

In another optional embodiment, a printed circuit board (PCB) includes the planar antenna.

According to the teachings of the present embodiment there is provided phased array antenna system including a plurality of the planar antenna, the plurality of antennas being mounted on a common substrate and operating collectively to provide a combined output beam.

According to the teachings of the present embodiment there is provided antenna system including: at least one of a reflective or refractive element having a focal site, and at least one planar antenna of claim 1 located at the focal site and deployed to feed the at least one reflective or refractive element, the at least one planar antenna being mounted on a common substrate.

According to the teachings of the present embodiment there is provided a broadband dual band antenna including:

a ground plane;

a first patch antenna element mounted in spaced relation to the ground plane and radiating towards a zenith in a first frequency band;

a second patch antenna element generally concentric with the first patch antenna element and radiating towards the zenith in a second frequency band;

a first feed arrangement for feeding the first patch antenna element; and

a second feed arrangement for feeding the second patch antenna element.

In an optional embodiment, a dimension of the first patch antenna element is smaller than a dimension of the second patch antenna element and the first frequency band is higher than the second frequency band.

In another optional embodiment, the first frequency band includes the Ka band for satellite communication and the second frequency band includes the K band for satellite communication.

In another optional embodiment, the first frequency band includes the K band for satellite communication and the second frequency band includes the Ku band for satellite communication.

In another optional embodiment, the first frequency band includes the K band for satellite communication and the second frequency band includes the X band for satellite communication.

In another optional embodiment, the first frequency band includes the Ku band for satellite communication and the second frequency band includes the X band for satellite communication.

In another optional embodiment, the first frequency band includes the L band for GPS communication and the second frequency band includes the L band for GPS communication. In another optional embodiment, the first and second patch antenna elements are similarly shaped,

In another optional embodiment, also including a conductive fence

circumferentially surrounding the first and second patch antenna elements and the first and second feed arrangements.

In another optional embodiment, the fence has a radius of less than ¾ of a wavelength of the first frequency band.

In another optional embodiment, also including a choke enclosure at least partially surrounding the conductive fence.

In another optional embodiment, the choke enclosure includes at least one conductive trench circumferentially surrounding the conductive fence.

In another optional embodiment, the choke enclosure includes a portion of the ground plane forming a base of the choke enclosure, an array of erect conductive elements mounted on the ground plane forming a wall of the choke enclosure and a conductive rim mounted on the array of erect conductive elements and extending over at least a portion of the ground plane and forming a roof of the choke

enclosure, the conductive rim having an inner circumference greater than a circumference of the conductive fence.

In another optional embodiment, the choke enclosure has a width of less than ¾ of a wavelength of an intermediate frequency and a depth of less than a ¾ of the wavelength, the intermediate frequency lying between the first and second frequency bands.

In another optional embodiment, the first feed arrangement includes a first plurality of generally L-ehaped feed probes feeding a first signal to the first patch antenna element and arranged at equally spaced angular intervals with respect to an axis extending through a concentric center of the first and second patch antenna elements; and the second feed arrangement includes a second plurality of generally L-shaped feed probes feeding a second signal to the second patch antenna element and arranged at equally spaced angular intervals with respect to the axis, each of the first plurality of feed probes being angularly shifted with respect to a

corresponding one of the second plurality of feed probes.

In another optional embodiment, the first plurality of feed probes is connected to one of a high frequency band pass filter or a high pass filter and each of the second plurality of feed probes is connected to one of a low frequency band pass filter or a low pass filter.

In another optional embodiment, the first and second patch antenna elements radiate with a first and second beams, each of the beams is one of linearly, circularly or elliptically polarized, a polarization of each of the first and second beams being independently controlled by an amplitude and phase of the signal provided by the first and second pluralities of feed probes respectively.

In another optional embodiment, each of the first and second beams includes two mutually orthogonal polarizations, the two mutually orthogonal polarizations being one of linear or circular polarizations.

In another optional embodiment, the antenna includes at least one non- rotationally symmetric element and the first and second patch antenna elements radiate with a non^rotationally symmetric beam.

In another optional embodiment, the at least one non-rotationaUy symmetric element includes at least one of the choke, the fence and the first and second patch antenna elements.

According to the teachings of the present embodiment there is provided a phased array antenna system including a plurality of antennas according to any of the preceding claims, the plurality of antennas being mounted on a common substrate and operating collectively to provide a combined output beam.

According to the teachings of the present embodiment there is provided an antenna system including at least one of a reflective or refractive element having a focal site and at least one antenna according to any of the preceding claims located at the focal site and feeding the at least one reflective or refractive element.

In another optional embodiment, the at least one antenna includes a multiplicity of antennas, the multiplicity of antennas being mounted on a common substrate and operating mutually independently.

According to the teachings of the present embodiment there is provided a feed antenna for at least one of a reflector or refractor in an antenna system including:

a first patcb antenna element radiating in first frequency band; and a second patch antenna element radiating in a second frequency band, the first and second patch antenna elements in combination with the at least one of a reflector or refractor radiating a first and second beams having a cross- polarization of less than -20dB, the first and second patch antenna elements in combination with the at least one of a reflector or refractor radiating with an efficiency of greater than 50%.

In another optional embodiment, also including:

a ground plane, the first patch antenna element being mounted in spaced relation to the ground plane and radiating towards a zenith in the first frequency band, the second patch antenna element being generally concentric with the first patch antenna element and radiating towards the zenith in the second frequency band;

a first feed arrangement for feeding the first patch antenna element; and

a second feed arrangement for feeding the second patch antenna element.

Brief description of figures

Fig. 1 is a schematic in perspective view of a cross-section of an antenna structure depicting the different layers composing the antenna structure.

Figs. 2(a)~(d) present perspective views of a schematic of the antenna structure:

Fig. 2(a) presents the complete structure.

Fig. 2(b) presents the top layer D3 flipped with the D3 bottom side that contains 22H and 27 facing up (which is not visible in Fig. 2A).

Fig. 2(c) is the antenna with the top layer D3 removed and without annular patches (22L, 22H) and choke cover 27.

Fig. 2(d) the same as Fig. 2(c) without the dielectric substrates Dl,

D2.

Fig. 3 is a cross section schematic of an embodiment with an external choke enclosure.

Fig. 4(a) presents an illustrative schematic diagram of an embodiment of the antenna with distributed microstrip filters implemented on the back side of the device, layer C4.

Fig. 4(b) presents an illustrative schematic diagram of an embodiment with RF frontend chips assembled on the back side of the device. Fig. 5 presents a simplified block diagram of a typical RF front end connected to the antenna.

Figs. 6(a)-(c) depicts different polarization schemes that can be implemented with the antenna.

Fig. 7 presents a schematic of a multi-antenna feed board.

Fig. 8 presents a schematic of an antenna array composed of the single antenna design.

Figs. 9(a)-(b) present the return loss of a sample embodiment in the K and Ka bands.

Figs. 10(a)-<b) present the efficiencies of a sample embodiment in the K and

Ka bands.

Fig. ll(a)-(b) present the beam-widths of a sample embodiment in the K and Ka bands.

Fig. 12(a)-(b) present the radiation patterns of a sample embodiment in the K and Ka bands.

Fig. 13(a)-(b) present the phase radiation patterns of a sample embodiment in the K and Ka bands.

Fig. 14(a)-(b) present illustrative embodiments serving as an antenna feed for primary and offset parabolic dish reflectors.

Fig. 15(a)-(b) present efficiencies of primary and offset reflectors, with the sample embodiment serving as a feed antenna, for both frequency bands: K and Ka.

Fig. 16(a)-(b) present radiation patterns of a primary reflector, with the device of the sample embodiment serving as a feed antenna, for both frequency bands: K and Ka.

Fig. 17(a)-(b) present radiation patterns of an offset reflector, with the device of the sample embodiment serving as a feed antenna, for both frequency bands: K and Ka.

Detailed Description - Figs. I to 17(b)

The principles and operation of the system according to a present

embodiment may be better understood with reference to the drawings and the accompanying description that is descriptive and not limiting. For the sake of brevity, some well-known features, methods, systems, procedures, components, circuits, and so on, are not described in detail.

A. The structure

Referring to Fig. 1, there is shown a schematic in perspective view of a cross- section of an antenna structure device 10 depicting the different layers composing the antenna structure 10. The antenna structure 10 facilitates a new class of multilayer integrated planar antenna and RF frontend capable of dual frequency band operation with high performance in both bands, a highly symmetric beam, low cross polarization level and independently selectable polarization for each band, linear, circular or elliptical polarization.

The antenna structure can be implemented as a multi-layer printed circuit board (PCB) or chip, composed of a stack of conducting and dielectric substrate layers as detailed in Table 1, below. In the production process, the conducting metallic layers are shaped, typically by etching, to provide desired metallic features, as commonly known in the art (for these layers only the final etched components are presented in Fig. 1). The antenna structure 10 is composed of a conductin g ground plane (layer) CO, a first dielectric substrate layer Dl mounted on top of the ground plane, a first conducting layer CI that is etched for creating four high band feed probe elements 21H (three of which high band feed probe elements are visible in the current figure), and four low band feed probe elements 21L (two of which are visible in the current figure). The first conducting layer Cl is preferably mounted on top of the first dielectric layer Dl . A second dielectric substrate layer or air D2 is mounted on top of the first conducting layer Cl. A second conducting layer C2 is etched for creating a high band annular patch antenna element 22H and choke cover 27 (not shown in the current figure). The second conducting layer C2 is mounted on top of the second dielectric substrate layer D2. A third dielectric layer D3 is mounted on top of the second conducting layer C2. A third conducting layer C3 is etched for creating a low band annular patch antenna element 22L and mounted on top of the third dielectric layer D3. A fourth dielectric layer D4 is mounted below the ground plane CO. A fourth conductive layer C4 is mounted below the fourth dielectric layer D4 and etched for creating distributed filters 41L, 41H (not shown in the current figure). Fence 25 and choke side conducting elements 26 are made of vertical conducting elements that connect the ground plane CO and the second conducting layer C2.

High band relates to the frequency band of operation of the high band patch antenna element 22H and high band feed probe elements 21H. Low band relates to the frequency band of opera tion of the low band patch antenna element 22L and low band feed probe elements 21L. The low frequency band is different and lower than the high frequency band.

The first patch antenna and the second patch antenna are generally concentric. In the context of this document, the term "generally concentric" refers to a center point of the first patch antenna (high band patch antenna 22H) being substantially aligned with a center point of the second patch antenna (low band patch antenna 22L) in a direction normal to the ground plane CO.

The second patch antenna is disposed around the first patch antenna.

The first and second patch antennas can each be in a respective layer. For example, the (first) high band patch antenna 22H in the second conductive layer C2 and the (second) low band patch antenna 22L in the third conductive layer C3, with the second and third conductive layers separated by the third dielectric layer D3. Alternatively, the first and second patch antennas can both be in the same layer. For example, the high band patch antenna 22H and the low band patch antenna 22L in the second conductive layer C2.

In the context of this document, the term "spaced relation" generally refers to elements being in different planes, for example, different layers of a PCB structure separated by a dielectric layer.

Table 1: layers stack description from top to bottom

In other embodiments, a plurality of stacked bottom dielectric and conductive layers can be mounted below the fourth dielectric substrate D4 to host the RF frontend wiring and circuitry.

In another embodiment, the low band and high band patch elements (22L,

22H) can be contained in the same conductive layer, thus eliminating the need for dielectric layer D3, as opposed to having both patch elements on different conductive layers as depicted in Table 1.

In another embodiment an additional dielectric layer can be placed on top of layer C3 and serve as a radome for protective purposes.

In another embodiment, the feed probe elements of the low and high bands (21L, 21H) can be contained on separate conductive layers with an additional dielectric substrate layer inserted in between the layers of the feed probe element 21L and 21JH, instead of having both groups of feed probe elements for high and low bands on the same conductive layer as was depicted in Table 1.

In another embodiment one or more of the dielectric layers can be air.

Fig. 2(a)-2(d) present perspective views of the antenna structure 10:

Fig. 2(a) presents a complete structure of the antenna structure 10, with low band annular patch 22L of layer C3 visible on top of the third dielectric layer D3.

Fig. 2(b) presents the third dielectric layer D3 flipped, so that the second conductive layer C2 with the high band annular patch 22H and choke cover 27, an annular conductive element, that were not visible in Fig. 2(a) are now visible.

Fig. 2(c) presents the structure without the layers C3, D3,€2, so that the internal feed probes structures (21L, 21H) are visible.

Fig. 2(d) is the same as Fig. 2(c) without the dielectric substrates Dl, D2.

The high band patch element 22H is an annulus or a disc and the low band patch element 22L is an annulus. For simplicity in this description, the high band patch element 22H will be referred to as an annulus. The high band patch element 22H typically has a radius smaller than the low band patch 22L. Thus, a gap exists between the low band annulus 22L and the high band annulus 22H. The patch elements (22H, 22L) are typically circular annulus shapes (round rings). In other embodiments, the patch elements may also be an annulus with a rectangular symmetry, hexagonal, or elliptical symmetry. In another embodiment, the inner patches can be solid shapes surrounded by annular shapes, for example an inner solid square surrounded by a square annulus. In another embodiment, the patches (22H, 22L) can be of different shapes, e.g. an inner annular ring patch and an outer square annulus patch.

The low and high band probe elements (21L, 21H) are typically planar rectangles. In other embodiments, the probe elements may have other shape geometries, e.g. a triangle or a trapezoid. The low band probe elements 21L are located at 45°, 135°, 225°, 315° degrees rotation relative to the center of the annulus and the positive X axis as defined in Fig. 2(a), and the high band probes elements 21H are located at 0°, 90°, 180°, 270° degrees rotation relative to the center of the annulus and the positive X axis. Therefore, the high band probes 21H are aligned with 45° rotation relative to the low band probes 21L. The probe elements (21L, 21H) are connected to filters (41L,41H) (not shown in the current figure) using respective vertical conductive elements (23L, 23H) accordingly, such as via conductive holes or conductive rods, through a clearance in the ground plane CO, to avoid short circuit to the ground CO. The probe elements (21L, 21H) provide proximity coupling to the patch elements (22L, 22H) and lie beneath the patch elements (22L, 22H) without direct electrical contact with the patch elements (22L, 22H).

In another embodiment, each or se veral of the feed probes (21L, 21H) may be coaxial feed probes with outer conductors connected to the ground plane CO and inner conductors connected to corresponding patch elements (22L, 22H) through a clearance in the ground plane CO, to avoid short-circuit.

In another embodiment, each or several of the feed probes (21L, 21H) may be replaced by aperture coupled feeds, provided by a transmission line, e.g. microstrip type in layer C4, and a slot in the ground plane CO feeding the patch elements (22L, 22H).

As commonly known in the art, a choke ring structure is a concentric metallic trench slot with a rectangular cross-section that circumferentially surrounds the antenna with a typical depth of 1/4 wavelength of the operating frequency. The choke structure is usually added to horn type antennas, in order to improve horn antenna radiation performance.

An innovative feature of the current embodiment is the use of a choke enclosure with a planar antenna, which can support successfully dual band antennas, also referred to in the context of this document as a choke enclosure. The conventional choke structure is upgraded with the addition of choke cover, an annular conducting surface 27 that partially covers the conventional choke structure. Optimization of the choke enclosure dimensions allows obtaining improved antenna radiation characteristics in both bands simultaneously.

A choke enclosure can be created as part of the PCB production process by the following elements: a) ground plane CO at the bottom, b) the choke sides are generated using a circular perimeter of dense conducting elements 26 that stretch typically from the high band radiating element layer (second conducting layer C2) or the probes layer (first conducting layer CI) to the ground plane CO and

electrically connected to the ground plane CO and c) the choke cover 27 is an annular conducting element that is etched of the second conductive layer C2 (as the high band patch element 22H), covering and in contact with the side conducting elements 26 and has an inner radius which is between an outer radius of the side conducting elements 26 and a radius of the fence 25. The height of the choke enclosure, given by the height of conducting elements 26 is typically under 1/4 wavelength of an intermediate frequency. The width of the choke enclosure is given by the gap distance between the fence 25 and the choke side 26, is typically under 1/4 wavelength of an intermediate frequency. The term intermediate frequency typically relates to a frequency that is between the low and high frequency bands and can vary with design optimization (that is, a frequency higher than the low band frequency and lower than the high band frequency).

The choke enclosure side 26 is typically implemented as part of the PCB production process using a tight circular perimeter of conducting vias (conductive plated holes), rods, a continuous metallic surface, or a combination of those elements, which are all electrically connected to the ground plane CO. In another embodiment, the perimeter of the choke side 26 can have other than circular symmetry, e.g. rectangular, elliptical, or hexagonal perimeter.

The patch and probe area are cireumferentially surrounded with the conducting fence 25. A typical height of the fence 25 extends from the second conductive layer C2 to the ground layer CO and connected to the ground layer CO. The height of the fence 25 may be higher or lower than layer C2 according to design requirements. The radius of the fence is typically a little under 0.5 times the wavelength of the high band.

The fence 25 is typically implemented as part of the PCB production process using a tight circular perimeter of conducting vias (conductive plated holes), rods, a continuous metallic surface, or a combination of those elements that are all electrically connected to the ground plane. In another embodiment, the perimeter of the fence can have other than circular symmetry, e.g. rectangular, elliptical, or hexagonal perimeter.

Fig. 3 presents an alternative embodiment with a fence and choke enclosure 31 implemented as a single external mechanical enclosure that hosts the printed feed structure 10. A depth of the choke enclosure 31 stretches from the bottom of D3 to the bottom of the choke enclosure 31, and is t3T)ically around 1/4 of an intermediate frequency. In this implementation, layer C3 is eliminated and the patch elements 22L, 22H are both etched out of layer C2, at the bottom side of layer D3. In this embodiment, layer D2 is an air gap.

In another embodiment, the perimeter of the choke enclosure 31 can have other than circular geometry, e.g. rectangular, elliptical, or hexagonal

circumference.

In another embodiment, the choke enclosure 31 can have a structure implemented as two (or more) concentric trenches and choke covers, side by side.

In another embodiment, the choke enclosure 31 can have a structure implemented as two (or more) concentric trenches, side by side. The inner trench has a depth around quarter wavelength of the high band and the outer trench has a depth around quarter wavelength of the low band.

Referring to Fig. 4(a) there is shown an embodiment with distributed filters that are printed as part of the antenna device 10. Each feed probe (21H, 21L) is connected to a filter. A low or bandpass filter 41L is connected to each of the low band feed probes 21L of the low band annulus 22L using respective vertical conductive elements 23L. A high or bandpass filter 41H is connected to each of the high band feed probes 21H of the high band annulus 22H using respective vertical conductive elements 23H. In another embodiment, filter chips can be assembled as part of the RF frontend instead of, or in addition to, the distributed filters (41H, 41L).

Fig. 4(b) presents the bottom side of a sample embodiment with an

exemplary 2.5mm by 2.5mm footprint of commercial RF frontend silicone core chips (low band 42L, high band 42H), four chips for each band. This embodiment typically requires an addition of two conductive layers and two dielectric substrate layers for the wiring of the chips.

Referring now to Fig. 5 there is shown a simplified block diagram of a typical RF frontend connected to the antenna. The RF frontend contains a separate RF chain for each feed probe. The current figure presents a schematic of a simplified transmit mode (high band) - Tx' RF frontend containing variable gain control 51H, variable phase control 52H, a power amplifier 53H and a filter 54H. The current figure also presents a schematic of a receive mode (low band) - 'Rx' RF frontend containing a filter 54L, LNA (low noise amplifier) 53L, variable phase control 52L and variable gain control 51L. In another embodiment, the RF frontend may contain additional amplification stages. The RF frontend may contain additional dielectric and metallic layers for wiring the RF frontend, which can be produced with the antenna as part of the same printed circuit board (added below later D4).

In Rx mode, the RF chains of the four feed probes, each as described in Fig. 5 are combined equally and down converted to an intermediate frequency (IF) band to provide an output signal. In Tx mode the intermediate frequency input signal is upconverted and split equally to the four RF chains of the corresponding feed probes, as described in Fig. 5.

In another embodiment, the required phase shifts of the feed probes can be provided using delay lines (transmission lines with required length that provides the necessary phase shift) or 90deg and 180deg ('rat-race') hybrid coupler

components.

In other embodiments, the antenna can be generalized to support additional frequency bands by adding additional external annular patches (for example, three annular patched for three bands) and corresponding feed probes.

In another embodiment, the number of the feed probes that correspond with each band and radiating patch antenna element can be other than four. In general, configurations with symmetric number and placement of probes are preferred for most applications due to usually better performance. The most common cases include four high band and four low band feed probes, four high band and two low band feed probes, two high band and four low band feed probes and two high band and two low band feed probes.

B. Principles of operation

1. Dual frequency band operation

The dual band operation is achieved by using two co-located annular patch antennas 22L and 22H operating in basic modes of radiation (with radiation to zenith, normal to the ground plane CO). Typically, the outer annulus (low band patch antenna element, 22L) operates at the low frequency band and the inner annulus (high band patch antenna element 22H) at the high frequency band. Each annular patch is typically fed by four feed probes, the four low band feed probes 21L located at 45^c, 135°, 225°, 315° degrees rotation relative to the center of the annulus and the positive X axis, and the four high band feed probes 21H located are 0°, 90°, 180°, 270° degrees rotation relative to the center of the annulus and the positive X axis. The typical but not restricting ratio of the center frequencies of both bands (ratio of high band to low band) spans from 1.3 to 2.

2. Polarization control

Polarization selection can be achieved by selecting the amplitude and the phase of each feed probe with the RF frontend. For each band , linear polarization is achieved by stimulating simultaneously only two feed probes which are rotated 180° apart (diagonally opposed), for example in the high band 0° and 180° for vertical polarization - V, or 90° and 270° for horizontal polarization - Ή¹. The two probes are stimulated with equal amplitude and 180° phase difference to create a mutual in-phase operation at these two feed locations. This is because the fields of the annular patch basic resonating mode are 180° out phase at these two feed locations.

An arbitrary angle linear polarization can be generated for each band by stimulating simultaneously both orthogonal polarizations H and V in the same phase and controlling the relative amplitude of the V probes relative to the H probes, in order to achieve any linear polarization angle given by Arctan(Ev/EH), with Ev and EH being the components of the Far-Field electric field of polarizations V, H. For example, in the high band, the following set in table 2 produces 45° linear polarization.

Table 2

Circular polarization can be generated for each band by using a sequential rotation strategy for a chosen band with all feed probes stimulated simultaneously and with angular progressive phase shift of 90°. As an example, in the high band, the following set in Table 3 produces the required stimulation for creating circular polarization.

Table 3

The handedness of the circular polarization, namely RHCP/LHCP (right/left hand circular polarization) can be determined by the phases of the probes.

The most general case of arbitrary elliptical polarization can be generated for each band by stimulating simultaneously both orthogonal polarizations H and V and varying the relative amplitude and phases of the V probes relative to the H probes (the private case of circular polarization for example is the case with the identical amplitudes of the H and V feed probes and phase difference between the H and V probes of +90°/-90° depending on the handedness).

The previous examples were presented for the high band feed probes. The same logic is applied to the polarization of the low band feed probes for generating an arbitrary polarization. Fig. 6(a) presents an embodiment in which all 4 feed probes 60 (corresponding to the low band feed probes 21L or the high band feed probes 21H) that are connected to the feed probes corresponding RF frontend chains are used with a function 61 of equal summation to generate a combined

input/output signal 62 (in this case input) in Rx (receive mode) mode, or the function 61 being equal division from the input/output signal 62 (in this case output) in Tx (transmit mode) mode, allowing the selection of any desired

polarization for a given band of operation. Dual-direction arrows are used to indicate that the operation of the schemes described in the current figure can be either for Tx with an outgoing signal or Rx with an incoming signal. This

embodiment relates to each band of operation independently.

Fig. 6(b) describes another embodiment in which, the system can be set as a pre-determined linear dually polarized system, with two independent

communication channels 64A and 64B one for each polarization. For example, in the high band linear orthogonal polarizations, e.g. V and H serve as independent channels. In this embodiment, each pair of probes 60 that are diametrically opposed and connected to corresponding RF frontend chains are used with a function being equal summation 63 to create output signals to the communications channels (64A, 64B) in Rx mode, or with equal division from input signals from the communication channels (64A, 64B) in Tx mode. This embodiment relates to each band of operation independently.

Fig. 6(c) describes another embodiment in which an addition of a 90"

(degree) hybrid coupler 65 to the system described in Fig. 6(b) allows dual circular polarization operation RHCP and LHCP over the independent communication channels (64A, 64B). This embodiment relates to each band of operation

independently.

An overall of two orthogonal polarizations can be set for each band, thus allowing 4 independent polarization communication channels in total. For example, the system can be set as V and H polarizations for the low band and RHCP and LHCP for the high band. In another embodiment, a more basic device can be made with a single polarization for each band, e.g. V polarization in the low band and RHCP polarization in the high band.

In another embodiment, polarization selection can be set dynamically by the RF frontend, in order for example, to match a varying polarization of a dynamic transmitt«r/receiver or medium transmission for achieving maximal throughput, 3. Broad band operation

Proximity feed probes with L-shape, generated by the feed probe element

(21L, 21H) and vertical conducting elements (23L, 23H), are a known strategy to obtain broadband microstrip patch antennas. Despite that, in this configuration, each probe independently does not provide the necessary return loss conditions for a good broadband antenna performance. Broadband operation is achieved by two main strategies: a) the symmetric feed configuration of the probes, namely the simultaneous excitation of each pair of diametrically opposed feed probes (relating to the 4 feed probes of each band), with an equal amplitude and 180° phase shift, provides a balanced feed configuration for the basic radiating mode of the patch antenna radiator with a broadband performance, unlike single feed configurations b) The fence 25 that circumferentially surrounds the patch radiators and connected to the ground layer CO creates effectively a cavity that contains the patch radiator and affects the patch radiator radiation properties. Proper tuning of the feed structure geometry and the fence 25 radius and height allows controlling the S- parameters (scattering parameters) of the first and second diametrically opposed feed probes that compose each pair, so that (relating to the first feed probe, but the argument is symmetrical for the second feed probe) the coupled Wave S s

close in magnitude, but opposite in phase (180º) to the returned wave SfireHJrst of the first feed probe, thus the two terms cancel each other to a good extent, and the overall active return loss at the first feed probe diminished (Active return loss: Sfoe_t-

and provides a good broadband performance. The fence 25 serves a crucial role is this broadband cancelation of the S parameters terms, and without the fence the device operates in a narrow band fashion.

4. Isolation/Low coupling

In a standard simultaneous operation of both bands (low and high) - full duplex, the resonating structure of each band, namely the feed probes (21L, 21H) and the annular patches (22L, 22H), can interfere with the successful independent operation of the other band, resulting in coupling between both structures, power loss and distorted radiation patterns. Successful independent operation of both bands is achieved by introducing filters that are connected to each feed probe and do not permit the operation outside the desired frequency band.

High or bandpass filters 41H are connected to the high band probes 21H and responsible for passing the high band and blocking the low band. Low pass or bandpass filters 41L are connected to the low band probes 21L and are responsible for passing the low band and blocking the high band. The filters ensure low coupling between the two frequency bands structures. The filter can be distributed planar filters that can be printed as part of the PCB or filter chips/blocks that can be assembled as part of the RF frontend.

Another factor that aids reducing the coupling between the high and low bands is the relative angular offset of 45° between the high band probes and the low band probes.

In an embodiment which uses hybrid couplers (90° or 180°) an additional coupling is provided by the couplers that are designed for each band specifically and do not operate well for the other and therefore provide some basic isolation.

Typical values of filters can vary between different types of applications.

When used in one-way mode for both high and low bands, e.g. receiving two generations of satellite TV, typically 2()dB filters are sufficient for successful

21 operation. Two-way systems are more demanding and require high isolation, typically better than 50dB_f

This issue of couplingAeakage does not exist when the antenna is used in half-duplex mode when the low band and high band are not operating

simultaneously (e.g. as with WIFI communication).

5. Low cross polarization and symmetric beam

A highly symmetric beam and low cross polarization is achieved at least in part using three strategies:

a) Symmetric feed configuration:

As described previously, for a specific band, linear polarization is generated by stimulating 2 probes that are diametrically opposed and stimulating the probes with 180° phase difference between the probes. The advantage of this configuration is provided by creating a symmetric and balanced stimulus of the basic radiating mode of the annular patches (22H, 22L) (unlike conventional single feed strategies), thus creating a highly symmetric beam. Another significant advantage is the cancelation of the cross-polarization fields of the two probes, which are opposite in phase due to the probes 180° phase difference in stimulation. In a similar fashion, a highly symmetric beam and low cross-polarization performance is obtained when all feed probes, namely two pairs of probes with orthogonal polarizations are

stimulated simultaneously, for example for generating circular polarization.

b) Fence

The fence 25 that is connected to the ground plane CO provides a cavity structure that encloses the patch radiators and strongly influences the properties of the radiated beams. The radius of the fence 25 is closely related with the beam- width and symmetry of the antenna beams and allows tuning parameters. This is crucial for when the antenna 10 serves as a feed for a reflector antenna for example. Successful reflector antenna illumination requires a highly symmetrical beam for obtaining high reflector antenna efficiencies.

c) Choke ring

The choke ring is a well-known strategy in horn design for reducing side and back lobes, enhancing the symmetry and reducing the cross polarization of the radiated beam, however, this strategy is rarely used with printed planar antennas. The conventional choke ring is typically a mechanical trench with a rectangular cross-section that is implemented on the circumference of the antenna with a typical depth of a quarter wavelength of the target frequency .

In the current embodiment, the conventional choke enclosure is upgraded with the addition of choke cover, an annular conducting surface 27 which is typically printed in the same layer C2 of the high band patch element 22H and with the remaining part of the top that stretches from the choke conducting elements 26 to the fence 25 being clear. By optimizing the choke enclosure depth, overall width and the width of the choke coyer 26 it is possible to obtain a choke enclosure that simultaneously provides good radiation performance for the two frequency bands.

The choke enclosure has a crucial role in shaping the radiated beams of both bands: controlling rotational symmetry, reducing undesired emitted radiation such as cross polarization fields and side lobe level, and boosting gains. This is crucial for successful reflector antenna illumination (for an antenna 10 that serves as a feed for a reflector antenna) and obtaining high reflector antenna efficiencies for example. Tuning the choke parameters also allows controlling the beam-widths of both bands, in some cases even equating the beam -widths, and therefore allows controlling the beam-width's suitability for illumination of a specific reflector antenna with given f/D ratio (focal length f to diameter D) which is closely related with the feed antenna beam-width.

6. Phase center

The two annular radiating patches (22L, 22H) are co-located, this creates almost identical phase centers of the beams of the low and high bands. This means that when this feed antenna 10 is placed at the focal spot of a reflector antenna system for example, there is no problem of loss emanating from axial defocusing in both bands, as might happen with dual band feeds having different phase centers for both bands.

C. Uses and advantages

Embodiments can be used as an antenna feed that is placed in the focal point or plane of a reflector/lens antenna system that contains one or more

reflective/refractive surfaces (or a combination of reflective and refractive surfaces). For example, a primary parabolic reflector or oflset parabolic reflector with a typical diameter of 1ft to 12ft. In addition, the high symmetry of the beams and the ability to tune the beam-widths in both bands enable relatively close or even identical beam-widths which correspond with high illumination efficiencies in both frequency bands. The feed can be typically designed for systems with f/D ratios (focal length f to diameter D) of 0.3-0.6.

Referring to Fig. 7, there is shown a schematic of multi-antenna board, with each antenna operating independently. This implementation can be used for example for MIMO (Multiple Input and Multiple Output) applications with spatial and polarization diversity or as a multi-feed antenna for reflector antennas.

Conventional multi-antenna feed systems for reflector antenna systems are often implemented by an assembly of several feed horn antennas that are located in the focal plane of the reflector system. A lateral offset from the focal point is translated to an angular offset of the beam, thus each feed horn points at a different direction in the sky which allows, for example, working with multiple satellites. In the current figure, a multi-antenna feed for a reflector antenna system is made by duplicating the design of a single feed 72 (here presented without the top dielectric) on the same printed circuit board 71 with designed lateral offsets, shown as single feeds 72A and 72B. This configuration of single feeds creates a fully integrated printed circuit board design of multiple feeds pointing at different directions. In this embodiment, each of the feeds (72, 72A, 72B) can be designed to support different frequency bands.

In another embodiment, designs can have deliberately non-symmetric beams over the main axes of the device, e.g. by using elliptical or rectangular symmetry for one or more of the followings: the annular patch element, fence or choke enclosure. This can be used for efficiently illuminating an elliptical reflector antenna which requires different beam-widths for the two main axes of the reflector for example.

Fig. 8 presents another embodiment, in which antenna without the choke enclosure can be used as an antenna element 81 in a standard array antenna or in a phased array antenna with dual-band operation. In this application, the beam of each band can be scanned independently pointing at different directions in space.

In other embodiments and applications, the device 10 can be used as a standalone antenna. The high azimuthal symmetry, broad elevation beam-widths, the possibility of working with circular polarization in both bands, and low footprint make the antenna device 10 especially suitable for applications where the direction of transmission/reception is unknown. Examples include antennas for drone communication and satellite IOT (internet of things) terminals.

Sample applications for the antenna device 10 include the following:

Two-way satellite communications, e.g. satellite internet in Ka, K, Ku, X, E and V bands.

One-way satellite communication in two frequency bands: e.g.

collocated DTH (direct to home TV) satellites in K and X bands.

Satellite IOT terminals.

A dual band GPS antenna operating in L band.

- Dual band WIFI applications, e.g. at 2.4 and 5 GHz bands.

Terrestrial communication links, e.g. for fifth generation 5G networks in Ka, K, E and V bands.

Energy harvesting applications.

D. Performance of a sample embodiment

A device for a collocated dual Ka band - K band reflector feed application with right handed circular polarization in both bands, e.g. for two-way satellite internet, was designed and evaluated using CST microwave studio, a commercial three- dimensional electromagnetic simulator. The device is based on the design that is depicted in Fig. 1 and Fig. 2 and was designed using commercial low loss Rogers 4003 LoPro laminates. The device presents superb performance as a parabolic reflector feed in both frequency bands of operation.

Figures 9(a) and 9(b) present the broadband return loss performance of the device in both bands. In the low band, the device has a 1.5 GHz bandwidth for return loss performance lower than -12dB, a common merit in satellite applications (the exact band can be better tailored to specific applications). In the high band, the return loss is lower than -15dB for all frequency band from 27.5GHz to 30GHz.

Figures 10(a) and 10(b) present the efficiency performance of the device in both bands. In the low band, the efficiency is higher than 85% over the bandwidth of operation and in the high band the efficiency is higher than 90% over the

bandwidth of operation. The efficiency includes the dielectric loss in the dielectric substrates, Ohmic loss in the conductors, surface roughness loss in the conductors, miss-match loss and coupling loss (between different ports). Figures 11(a) and 11(b) present the beam- widths of the device. 3dB beam- widths are presented for both bands and relate to the angular range between the half power points of the beam relative to the boresight value this is commonly defined as the "main-beam". lOdB beam-widths are presented for both bands and relate to the angular range between the 10% power points of the beam (10% of boresight value).

The 10dB beam-widths are roughly 135° in the low band and roughly 100° in the high band (relating to band centers). The lOdB beam-widths determine the f/D (focal length f to diameter D) ratio of an optimal parabolic dish that fits this feed. In this example, an optimal performance of the high frequency band is preferred, therefore a dish with f/D=0.55 corresponding with a beam-width of 100° is selected. Despite the low band performance is most suitable for an f/D=0.45 due to the higher beam-width, only a small degradation in efficiency of roughly 0.3dB is obtained in the low band for a dish with f/D of 0.55 and not 0.45. Different design versions may have more optimal beam-widths in both bands, such as the one depicted in Pig. 3 which can have equal beam-widths fitting f/D=0.45.

Figures 12(a) and 12(b) present the radiation patterns of both bands in the co-polarization and the cross-polarization patterns for two cross-sections phi=0° and phi=45° (the performance is identical between phi=90° and 0°, and between 45° and 135°). The planar feed structure located in the X-Y plane and the z-axie is the normal to the center of the feed. The angle Phi (φ) relates to the polar angle in the X-Y plane from the positive X-axis as described in Fig. 2. Extremely symmetric patterns are obtained with barely distinguishable differences. This is an important quality for an optimal illumination of a reflector. In addition, Cross polarization levels are also substantially lower than -20dB over the main beam, which is required for low cross polarization levels for a feed integrated with a reflector.

Figures 13(a) and 13(b) present the phase radiation patterns of the co- polarization components in both bands for cross-sections phi=0° (phase patterns are extremely similar in other sections and therefore not presented here). Phase patterns are extremely uniform with a variation lower than 10° over the main beam. High phase uniformity is required for efficient reflector illumination.

Figures 14(a) and 14(b) present examples of parabolic antenna systems with focal sites that are used with planar antennas 10 as feed antennas, as opposed to horn feed antennas. The parabolic dish antennae in these examples have f/D=0.55 and a diameter of 304.8mm. Fig. 14(a) presents a primary configuration, with the antenna 141 located in the focal site of a primary dish 142 and the main beam 143 is normal to the dish 142. Fig. 14(b) presents an offset dish 144

configuration in which the antenna 145 is located at a focal site with an angular offset relative to normal to the dish, creating a beam 146 with an angular shift, relative to the normal to the dish 144.

Figures 15(a) and 15(b) present the efficiencies of the integrated feed-dish systems of Fig. 14 in both bands and both configurations: primary parabolic dish and offset parabolic dish. High efficiencies, well over 50% are obtained for both bands and both dish configurations.

Figures 16(a) and 16(b) present the co-polarization and cross-polarization radiation patterns of the primary dish antenna configuration in both bands for different cross sections phi-0°, 45° (the performance is identical for cross sections phi=0° and 90° and for 45° and 135°). Extremely symmetric patterns and low cross polarization levels, more than 30dB below the co-polarization are obtained.

Figures 17(a) and 17(b) present the co-polarization and cross-polarization radiation patterns of an offset dish antenna configuration in both bands for different cross sections phi=0°, 90°. Relatively symmetric patterns and low cross polarization levels, more than 30dB below the co-polarization are obtained.

Note that the above-described examples, numbers used, and exemplary calculations are to assist in the description of this embodiment. Inadvertent typographical errors, mathematical errors, and/or the use of simplified calculations do not detract from the utility and basic advantages of the invention.

To the extent that the appended claims have been drafted without multiple dependencies, this has been done only to accommodate formal requirements in jurisdictions that do not allow such multiple dependencies. Note that all possible combinations of features that would be implied by rendering the claims multiply dependent are explicitly envisaged and should be considered part of the invention.

Claims

WHAT IS CLAIMED IS

1. A planar antenna comprising:

(a) a ground plane (CO),

(b) a first patch antenna (22H) mounted in spaced relation to the ground plane and radiating towards a zenith normal to said ground plane in a first frequency band,

(c) a second patch antenna (22L) generally concentric with said first patch antenna and radiating towards said zenith in a second frequency band, said second frequency band other than said first frequency band,

(d) a first feed arrangement including a first set (21H) of two or more feed probes, said first feed arrangement feeding a first signal to said first patch antenna, and

(e) a second feed arrangement including a second set (21 L) of two or more feed probes, said second feed arrangement feeding a second signal to said second patch antenna, wherein each said set of feed probes (21H, 21L) is respectively disposed at angular intervals with respect to an axis extending through a concentric center of said first and second patch antenna elements.

2. The planar antenna of claim 1 wherein:

(a) a radius of said first patch antenna is smaller than a radius of said second patch antenna, and

(b) said first frequency band is higher than said second frequency band.

3. The planar antenna of claim 1 wherein a shape of said first and second patch antennas is selected from the group consisting of:

(a) the same shape,

(b) different shapes,

(c) different annular shapes,

(d) annular,

(d) circular rings,

(e) a centra] patch and a surrounding annular shape.

4. The planar antenna of claim 1 , wherein said first and second patch antennas are disposed in a layer of the planar antenna selected from the group consisting of: (a) the same layer,

(b) different layers (C2, C3), and

(c) different layers separated by a third dielectric layer (D3).

5. The planar antenna of claim 1, wherein said first frequency band and said second frequency band are respectively selected from the group consisting of:

the Ka band and the K band,

the K band and the Ku band,

the K-band and. the X-band,

the Ku-band and the X-band,

the WIFI bands,

the L-bands for GPS communication, and

a ratio of a center frequency of said high band to a center frequency of said low band is in a range from 1.3 to 2.

6. The planar antenna of claim 1 , wherein said angular intervals are equally spaced.

7. The planar antenna of claim 1 , wherein said first set (21 H) and second set (21 L) of feed probes each include four feed probes.

8. The planar antenna of claim 1 , wherein each of said feed probes (21 H, 21 L) is connected to a conductive element (23H, 23L), each said conductive element (23H, 23L) extending through, and insulated from, said ground plane (CO).

9. The planar antenna of claim 1 , wherein said feed probes (21H, 21L) are separated from said patch antennas by a second dielectric layer (D2).

10. The planar antenna of claim 1 , wherein:

(a) said first set of feed probes are operationally connected to a high or bandpass filter, and

(b) said second set of feed probes are operationally connected to a low or bandpass filter.

11. The planar antenna of claim 7 wherein said first set (21H) and second set (21L) of feed probes each connect to respective R.F chains, each RF chain for transmitting and receiving signals via respective first and second patch antennas (22H, 22L).

12. The planar antenna of claim 1 further including:

(f) a conductive fence (25): antennas,

13. The planar antenna of claim 12 wherein said conductive fence (25) has a radius less than 1/2 of a wavelength of said first frequency band.

14. The planar antenna of claim 12 further including:

(g) a choke enclosure (31B):

(i) disposed circumferentially surrounding said first and second patch antennas, and

(ii) electrically connected to said ground plane (CO).

15. The planar antenna of claim 14 wherein:

(a) a height of said choke enclosure (31B) is less than ¼ wavelength of an intermediate frequency, and

(b) a width of said choke enclosure (31 B) is less than ¼ wavelength of said intermediate frequency,

said intermediate frequency being a frequency lower than said first frequency band and higher than said second frequency band, and

said width being a gap distance between:

(i) an inner radius of said conductive fence (25), and

(ii) an outer radius of conducting elements (26), said conducting elements (26) disposed circumferentially surrounding said conductive fence (25), and electrically connected to said ground plane (CO).

16. The planar antenna of claim 15 wherein said conductive fence (25) and said conducting elements (26) are made of vertical conducting elements that connect the ground plane (CO) and a second conducting layer (C2).

17. The planar antenna of claim 1 wherein said first and second patch antennas radiate with respective first and second beams, each of said beams is one of linearly, circularly or elliptically polarized, a polarization of each of said beams being independently controlled by an amplitude and phase of said first and second signals provided by said first and second feed arrangement.

18. A printed circuit board (PCB) comprising the planar antenna of claim 1.

19. A phased array antenna system comprising a plurality of planar antennas of claim 1 , the plurality of antennas being mounted on a common substrate and operating collectively to provide a combined output beam.

20. An antenna system comprising:

at least one of a reflective or refractive element having a focal site, and at least one planar antenna of claim 1 located at said focal site and deployed to feed said at least one reflective or refractive element,

the at least one planar antenna being mounted on a common substrate.