Architecture for antenna

Abstract

The present disclosure relates to an architecture for an antenna. The architecture provides an antenna array comprising a plurality of antenna elements, transceiver circuitry for controlling the gain and phase of signals received at and to be transmitted from each antenna element, and a diplexer array. The diplexer array comprises, for each antenna element, a diplexer pair. Each diplexer is generally elongate has a longitudinal axis that extends through and generally orthogonal to a radiating surface of a corresponding antenna element. Each diplexer has a transverse cross-sectional footprint that supports a spacing between the diplexers in the diplexer array of no greater than half a wavelength of radio waves at a highest frequency of operation.

Description

[0001] Architecture for Antenna

[0002] The present invention relates to antenna architectures. The invention has particular although not exclusive relevance to an antenna architecture for a multi-band shared aperture transmitter / receiver mmWave phased array with potential application in a wide range of use cases including for dual polarisation for 5G applications.

[0003] As telecommunication systems have developed, there is an increasing requirement to support equipment that communicates in the mmWave region of the electromagnetic spectrum (typically defined as covering frequencies in the 30GHz to 300GHz range, but commonly used to refer to spectrum down to 24GHz as well in the context of 5G cellular systems). Historically, communication using the millimetre wave (mmWave) band was relatively limited including applications such as mobile satellite communication (SatCom) on the move (SOTM) in the Ka(26.5-40 GHz) band, and short-range, high throughput high capacity indoor communication in the 60GHz industrial, scientific, and medical (ISM) band for stationary wireless devices.

[0004] As cellular communication systems evolve from 4G, to 5G, and beyond, deployment is being planned a variety of previously underutilised spectrum bands. Whilst initial deployments use frequencies below 1 GHz, and later deployments will likely use frequencies between 1 and 6 GHz, for the first time deployments are being considered for spectrum beyond 6 GHz, and in the mmWave frequency range. The use of mmWave frequencies has the potential to provide a considerable amount of spectrum for future 5G (and beyond) broadband mobile communication networks to support the ever increasing capacity demands of such communication networks. Moreover, appropriate use of this frequency spectrum is expected to provide a significant increase in the performance of the cellular network. In addition to the increased bandwidth, utilising mmWave spectrum is expected to provide support for massive parallel communications and ultra-dense networks.

[0005] These high frequency applications, and in particular in the mmWave range, generally require antenna architectures that integrate advanced phased array antennas for supporting beamforming and steering capabilities, and transmitter and receiver operations in different respective frequency regions. Typically, in such architectures, the receiver and transmitter operations are achieved by means of separate transmitter and receiver radiating apertures, which increases the volume required for implementation. Integration of both transmitter and receiver operation into a single aperture is, therefore, desirable. Single aperture antennas typically comprise: a ‘broadband’ antenna array in which each element of the array is designed for operation across a bandwidth that is large enough to cover the respective frequency bands for both the transmitter and the receiver; or a ‘dual-band’ array in which the arrays comprises separate transmitter and receiver elements designed for operation in separate frequency bands (albeit that the separate transmitter and receiver elements may be coaxially aligned to form integrated ‘dual-band’ elements). It will be appreciated that, in the context of cellular communication (e.g., 5G), this is applicable for: time division duplex (TDD) communication, in which it is convenient for a base station to be able to have a receive antenna always on, even when the base station is transmitting; and for frequency division duplex (FDD) communication in which "uplink" and "downlink" communication can occur simultaneously at two separate frequencies.

[0006] However, whilst integration of both transmitter and receiver operation into a single aperture is desirable, designing an effective and compact antenna architecture for a phased array antenna, that provides the required integration of and interconnectivity between the elements of the antenna and the associated beamforming networks, transmitter and receiver electronics, and other circuitry is not trivial. The design of an antenna architecture for a phased array antenna, having a multiband shared transmitter / receiver beamforming aperture, and that is required to operate at higher frequencies (e.g., in the higher GHz range associated with mmWaves) is a particularly challenging and complex task.

[0007] The requirements for time division duplex (TDD) communication tends to drive the requirements of the antenna front-end towards a broadband solution in which the same antenna element is used for reception and transmission. Moreover, the general requirement for the antenna element separation to be no more than half the wavelength (A) at the highest frequency of operation (referred to as the ‘A / 2’ requirement) results in an extremely dense array of antenna elements which makes effective integration with the supporting electronics more challenging. For frequency division duplex (FDD) communication, on the other hand, there is a need for separate transmitter and receiver channels on separate frequencies and hence a need to ensure appropriate isolation between any active transmitter and receiver. The specific isolation requirements tend to be dictated by transmitter noise and receiver blocking capability with a view to maximising performance. This is typically achieved in modern 5G systems with appropriate duplexing between the antenna and the power amplifier (PA) in the transmit path / low noise amplifier (LNA) in the receive path. Additional complications also arise form the need for dual polarization for 5G applications (or to give full flexibility for right-handed circular polarisation (RHCP) or left-handed circular polarisation (LHCP) selection.

[0008] Currently proposed solutions often focus on the layout and structure of the antenna array itself but do not address the additional complications that arise from the need to provide the necessary integration and interconnectivity between the elements of the antenna the associated beamforming chipsets, transmitter, and receiver electronics, and other circuitry. This typically results, therefore, in an antenna system having an arrangement of antenna elements that does not provide for effective and compact integration with beamforming integrated circuits, and especially the more widely available ‘off-the-shelf’ beamforming chips that would be necessary for large scale consumer applications.

[0009] Currently proposed solutions also tend to be relatively inflexible, with little frequency agility, and the antenna radiation pattern tends to be affected significantly by the band of operation and filtering (where filtering is used). Currently proposed solutions also tend to use polarisation as a means for providing isolation between antenna elements (e.g., for FDD purposes) and do not, therefore, fully support complete dual polarisation.

[0010] Some proposed solutions do not allow for the transmitter frequency and the receiver frequency to be used on the same phased array - effectively requiring one antenna for the transmitter and a separate antenna for the receiver, thus using more space in total and making system integration more complex. Some proposed solutions are unable to support the use of dual radio systems on two different frequencies on the same array. Some proposed solutions do not support configurable frequencies within an octave of one another, which is undesirable, in particular, if dual-band support is required for two frequencies (F1 and F2) that are very close one another.

[0011] For satellite communications, and more recently for the back-haul (feeder link) communication for high-altitude platforms (HAPs) used for non-terrestrial networks (NTN) being developed for cellular communication, FDD is used to help reduce latency (and therefore hence inefficiency). The transmitter and receiver frequency bands used, to allow such communication to work without using diplexers, have historically been separated in frequency by a significant amount.

[0012] The present invention seeks to provide one or more aspects of an improved antenna architecture. The present invention seeks to provide, in particular but not exclusively, an architecture that supports a multi-band (dual-band or greater) shared aperture. In one example described herein there is provided an antenna assembly for supporting communication in a plurality of frequency bands, the antenna assembly comprising: an antenna array comprising a plurality of antenna elements, each antenna element being respectively configured for reception and / or transmission of radio signals in at least a first frequency band and a second frequency band; transceiver circuitry for respectively controlling a gain and / or phase of signals received at and / or to be transmitted from each antenna element; and a diplexer array configured for transferring, between the antenna array and the transceiver circuitry, signals received at and / or to be transmitted from the antenna array; wherein the diplexer array comprises, for each antenna element, at least one respective diplexer, each diplexer being configured for diplexing signals received at and / or to be transmitted from that antenna element in the first frequency band, and signals received at and / or to be transmitted from that antenna element in the second frequency band; wherein each diplexer is generally elongate has a longitudinal axis that extends through and generally orthogonal to a radiating surface of a corresponding antenna element; and wherein each diplexer has a transverse cross-sectional footprint that supports a spacing between the diplexers in the diplexer array of no greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band.

[0013] The diplexer array may comprise, for each antenna element, a respective diplexer pair. Each diplexer pair may respectively comprise: a first diplexer for diplexing signals, received at and / or to be transmitted from that antenna element, and having a first type of polarisation; and a second diplexer for diplexing signals, received at and / or to be transmitted from that antenna element, and having a second type of polarisation. The first diplexer of each diplexer pair may have a first longitudinal cross section in a plane corresponding to the first type of polarisation, and the second diplexer of each diplexer pair may have a second longitudinal cross section in a plane corresponding to the second type of polarisation. The first longitudinal cross section of the first diplexer may intersect with the second longitudinal cross section of the second diplexer.

[0014] Each diplexer may have a first filter portion comprising a filter for allowing passage of signals in the first frequency band and a second filter portion for allowing passage of signals in the second frequency band. The first filter portion and the second filter portion may be generally elongate and extend generally parallel to one another and to the longitudinal axis of the diplexer. Adjacent diplexers of the diplexer array may be arranged in a manner whereby the first filter portions of the diplexers associated with at least one first two-by-two group of antenna elements may be closer to a centre of the at least one first two-by-two group of antenna elements than the second filter portions. Adjacent diplexers of the diplexer array may be arranged in a manner whereby the second filter portions of the diplexers associated with at least one second two-by-two group of antenna elements may be closer to a centre of the at least one second two-by-two group than the first filter portions.

[0015] The transceiver circuitry may comprise a plurality of connection ports for connecting the diplexers to corresponding transceiver circuitry. The plurality of connection ports may respectively comprise, for each diplexer: at least one first connection port for connecting the first filter portion to corresponding circuitry for transmitting and / or receiving in the first frequency band; and at least one second connection port for connecting the second filter portion to corresponding circuitry for transmitting and / or receiving in the first frequency band. Each first and / or second connection port may be generally aligned with the first and / or second filter portion for which it provides connectivity. The transceiver circuitry may comprise: at least one first integrated circuit, IC, for transmitting and / or receiving in the first frequency band; and at least one second IC for transmitting and / or receiving in the second frequency band. The at least one first IC may be positioned to have a centre that is aligned with a position within (e.g., equidistant from) a group of first connection ports for the diplexers of at least one first two-by-two group of antenna elements. The at least one second IC may be positioned to have a centre that is aligned with a position within (e.g., equidistant from) a group of second connection ports for the diplexers of at least one second two-by-two group of antenna elements. The at least one first IC may be generally aligned with a centre of at least one first two-by-two group of antenna elements. The at least one second IC may be generally aligned with a centre of at least one second two-by-two group of antenna elements. The at least one first two-by-two group of antenna elements, and at least one second two-by-two group of antenna elements, may have at least one antenna element in common.

[0016] Each first and / or second IC may be a dual polarization transmitter, receiver, or transceiver IC. Each first and / or second IC may be a four-ports, transmitter, receiver, or transceiver IC. Each first and / or second IC may be a beamforming, transmitter, receiver, or transceiver IC.

[0017] The plurality of connection ports may comprise a plurality of first type of polarisation connection ports for connecting at least one diplexer for diplexing signals having a first type of polarisation to corresponding circuitry for transmitting and / or receiving signals having the first type of polarisation. The plurality of connection ports may comprise a plurality of second type of polarisation connection ports for connecting at least one diplexer for diplexing signals having a second type of polarisation to corresponding circuitry for transmitting and / or receiving signals having the second type of polarisation. The plurality of first type of polarisation connection ports may be arranged in one or more rows in which the connection ports aligned with one another in a plane generally parallel to the radiating surface of the antenna array. The plurality of second type of polarisation connection ports may be arranged in one or more columns in which the connection ports aligned with one another in a plane generally parallel to the radiating surface of the antenna array.

[0018] Each diplexer may comprise a ridged waveguide diplexer. Each diplexer may comprise a substrate integrated waveguide, SIW, diplexer.

[0019] Each antenna element, of at least a subset of the antenna elements, may be respectively configured as a broadband antenna element that comprises at least one radiating element configured for reception and / or transmission at any of a range of frequencies including the first frequency band and the second frequency band.

[0020] Each antenna element, of at least a subset of the antenna elements, may be respectively configured as a dual- or multi- band antenna element that comprises a plurality of radiating elements. The plurality of radiating elements may comprise at least a first radiating element configured for reception and / or transmission in the first frequency band and a second radiating element configured for reception and / or transmission in the second frequency band. At least one frequency band of the first frequency band and second frequency band may be at a frequency of at least 10GHz, at least 20GHz, at least 25GHz, or at least 30GHz.

[0021] The diplexers of the diplexer array may be predominantly formed of a polymeric material. The diplexers of the diplexer array may be predominantly formed of a ceramic. The diplexers of the diplexer array may be manufactured using a 3D printing technology that provides a precision sufficient to support a spacing between the diplexers in the diplexer array of no greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band.

[0022] The diplexers of the diplexer array may be manufactured using an injection moulding technology that provides a precision sufficient to support a spacing between the diplexers in the diplexer array of no greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band. The transceiver circuitry may be configured to support time division duplex (TDD) communication and / or frequency division duplex (FDD) communication via the antenna array.

[0023] A spacing between adjacent antenna elements of the antenna array may be configured to be no greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band.

[0024] In one example described herein there is provided an antenna system comprising at least one antenna assembly as defined above and at least one software defined radio (SDR) or at least one radio frequency system on a chip (RFSoC) configured for controlling communication via the at least one antenna.

[0025] The antenna system may comprise a separate SDR, or a separate RFSoC, for respectively controlling communication via: each antenna element of each antenna assembly; or each of a plurality of different subsets of two or more antenna assembly elements of each antenna. The antenna system may comprise a respective software SDR, or a respective RFSoC, for respectively controlling communication via each antenna assembly of the antenna system. The antenna system may comprise a plurality of the antenna assemblies, wherein the or each SDR, or the or each RFSoC, is respectively configured for controlling communication via at least two antenna assemblies of the antenna system. The antenna system may comprise a plurality of the antenna assemblies, wherein the plurality of the antenna assemblies are arranged to form a sparse array antenna in which a separation between respective antenna arrays of different antenna assemblies is greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band. The antenna system may comprise a plurality of the antenna assemblies, wherein the plurality of the antenna assemblies are arranged to form a dense array antenna. The antenna system may comprise a plurality of the antenna assemblies, wherein each antenna assembly of the plurality of antenna assemblies is configured to provide a different respective receiver and / or transmitter beam. The antenna system may comprise a plurality of the antenna assemblies, wherein each antenna assembly of the plurality of antenna assemblies may be configured for providing a respective plurality of sub-beams which together form the different respective receiver and / or transmitter beam. The antenna system may comprise a plurality of the antenna assemblies, wherein at least one antenna assembly of the plurality of antenna assemblies is configured to operate in at least one frequency band that is different to the frequency bands that another antenna assembly of the plurality of antenna assemblies is configured to operate in.

[0026] Embodiments of the invention will now be described by way of example only with reference to the attached figures in which:

[0027] Figure 1 is a perspective view of an antenna system;

[0028] Figure 2 is a front view of the antenna system of Figure 1 ;

[0029] Figure 3 is a side view of the antenna system of Figure 1;

[0030] Figure 4 is an exploded view of the antenna system of Figure 1 ;

[0031] Figure 5 is an exploded view of an antenna array, and an arrangement of diplexers that may be used in the antenna system of Figure 1 ;

[0032] Figure 6 shows the antenna array, and arrangement of diplexers of Figure 5 in an assembled form;

[0033] Figure 7 is an exploded view of the antenna array and the arrangement of diplexers of Figure 5 together with a diplexer housing;

[0034] Figure 8 illustrates a diplexer pair, coupled to a corresponding antenna element, that may be used as a unit part of the arrangement of diplexers shown in Figures 5 to 7;

[0035] Figure 9 illustrates an individual antenna element that may be used as a unit part of the antenna array shown in Figures 5 to 7;

[0036] Figure 10 illustrates another antenna array, and arrangement of diplexers that may be used in the antenna system of Figure 1 ;

[0037] Figure 11 illustrates a diplexer pair, coupled to a corresponding antenna element, that may be used as a unit part of the arrangement of diplexers shown in Figure 10;

[0038] Figure 12 illustrates, schematically, possible diplexer to radiating element connectivity for antenna elements comprising broadband radiating elements that may be used in the antenna system of Figure 1 ;

[0039] Figure 13 illustrates, schematically, possible diplexer to radiating element connectivity for antenna elements comprising dual-band radiating elements that may be used in the antenna system of Figure 1 ; Figure 14 illustrates an arrangement of connection ports in a section of a beamformer board, for providing communicative connectivity between a ridged waveguide diplexer pair, of the type illustrated in Figure 8, and corresponding beamforming transmitter, receiver and / or transceiver ICs;

[0040] Figure 15 illustrates, in more detail, a ridge waveguide diplexer to beamformer board transition for the section of the beamformer board illustrated in Figure 14;

[0041] Figure 16 illustrates how the arrangement of connection ports shown in Figure 14 may be extended for providing communicative connectivity between an array of ridged waveguide diplexer pairs, of the type illustrated in Figure 8, and corresponding beamforming transmitter, receiver and / or transceiver ICs;

[0042] Figure 17 illustrates, schematically in plan, an interlaced arrangement of beamforming chipsets and their respective connectivity to the connection ports of each of a plurality of beamformer board sections of the type illustrated in Figures 14 to 16;

[0043] Figure 18 illustrates, schematically in plan, an interlaced arrangement of beamforming chipsets, and their respective connectivity to diplexer pairs of the type illustrated in Figure 8;

[0044] Figure 19, for example, illustrates, schematically in plan, an interlaced arrangement of transmitter and receiver beamforming chipsets, and their respective connectivity to diplexer pairs of the type illustrated in Figure 11 , of a diplexer array as illustrated in Figure 9;

[0045] Figure 20, for example, illustrates, schematically in plan, possible diplexer to radiating element connectivity for the diplexer array as illustrated in Figures 19 and 20;

[0046] Figure 21 illustrates, schematically, an application of the antenna architecture of to provide a multi-beam cluster of antenna arrays;

[0047] Figure 22 illustrates, schematically, an arrangement of a plurality of clusters multibeam clusters of the type described with reference to Figure 21 ; and

[0048] Figure 23 illustrates a specific sparse array configuration that may be realised using clusters as described with reference to Figures 21 and 22. Overview

[0049] An antenna architecture will now be described, by way of example only, with reference to Figures 1 to 4 which illustrate an antenna system generally at 100.

[0050] As seen in Figure 1, which is a perspective view of the antenna system 100, the antenna system 100 comprises: a beamformer board 112; a diplexer housing or 'caseworks’ 114 that is mounted on the beamformer board 112; an antenna array 116 that is surrounded, and held in position, by an antenna frame 118 that is mounted to the diplexer housing 114.

[0051] As seen in Figure 2, which is a front view of the antenna system 100, in the illustrated example the antenna array 116 and associated antenna frame 118 together form an antenna front end with the antenna array 116 being arranged within an inner perimeter of, and in general coaxial alignment with, the antenna frame 118. The antenna array 116 comprises a generally square 8 x 8 array of individual antenna elements 116-xy (where x is a column index and a member of {0,1, ...7}, and y is a column index and a member of {0,1 , ...7}). It will be appreciated that Figure 2 does not include reference numerals for all antenna elements for simplicity and clarity. It will also be appreciated that while a generally square 8 x 8 array is used in the illustrated example for ease of description, the antenna array 116 and associated antenna frame 118 may be of any suitable shape (e.g., rectangular, or generally circular) with the antenna elements 116- xy being arranged in any suitable corresponding formation with any suitable number of antenna elements.

[0052] As described in more detail later, each antenna element may be a broadband element configured both for transmission via that antenna element in (at least) a first frequency band (F1) and for reception via that antenna element in (at least) a second frequency band (F2). Alternatively, each antenna element may be a dual-band or multi-band compatible antenna element comprising: at least one transmission component for transmission via that antenna element in (at least) the F1 frequency band; and at least one reception component for reception via that antenna element in (at least) the second frequency band (F2).

[0053] As seen in Figure 3, which is a side view of the antenna system 100, the antenna front end, comprising the antenna array 116 and associated antenna frame 118, is aligned with, and mounted on, the diplexer housing 114. The beamformer board 112 comprises a multi-layered printed circuit board (PCB) / circuit card or similar in which transceiver circuitry comprising an arrangement of beamforming integrated circuits (ICs) 112-1 , together with associated electronics, is provided. In the illustrated example, the beamforming ICs 112-1 may include transmit ICs for controlling transmission and receive ICs for controlling reception and / or may comprise transceiver ICs that are configured for both transmission and reception. Each beamforming IC 112-1 comprises the phase shifting components and any variable gain components required for transmission or reception. The antenna architecture beneficially provides the flexibility to use off-the-shelf chipsets (transmit and receive), that those skilled in the art will be familiar with, or bespoke chipsets if needed. By way of example, the beamformer ICs 112-1 may typically comprise dual polarisation, quad channel, transceiver integrated circuits such as those sold by Anokiwave™ (e.g., with product codes AWMF-0221 (24- 30 GHz) or AWMF-0236 (37-43.5 GHz)).

[0054] The antenna architecture also beneficially provides the flexibility to use appropriate chipsets that support FDD operation and / or TDD operation.

[0055] The arrangement of beamforming ICs 112-1 and associated electronics is configured for, when the antenna system 100 is fully assembled and operating, providing individual gain and phase control for each antenna element respectively.

[0056] As seen in Figure 4, which is an exploded view of the antenna system 100, the diplexer housing 114 is configured to house, when fully assembled, an arrangement of diplexers 130 for respectively enabling the sharing of each antenna element between the frequency bands (F1 and F2 in this example). The diplexers are arranged to allow transmissions on different frequencies via the same antenna element and the potential for each band to be used for transmission, reception, or both transmission and reception. Specifically, in the exemplary antenna system 100, when fully assembled and operating, the arrangement of diplexers 130 is configured for filtering signals to be transmitted by the antenna array 116 from corresponding antenna elements (e.g., using the F1 frequency band). The arrangement of diplexers 130 is also configured for filtering signals received by the antenna array 116 at corresponding antenna elements (e.g., in the F2 frequency band). The arrangement of diplexers 130 is also configured for respectively splitting signals received at each antenna element into separate F1 and F2 paths (if reception in both F1 and F2 bands is required), and / or combining signals to be respectively transmitted from each antenna element into separate F1 and F2 paths (if transmission in both F1 and F2 bands is required). The arrangement of diplexers 130 is also beneficially configured for transmission and reception using two orthogonal linear polarisations - vertical and horizontal in the illustrated example (although a ± 45° orthogonal slant polarisations are also possible).

[0057] As described in more detail later, the arrangement diplexers 130 may comprise an arrangement of ridged waveguide based diplexers (as shown in Figure 4) or may comprise PCB based substrate integrated waveguide (SIW) filter based diplexers.

[0058] It will be appreciated that while the antenna system 100 is described in relation to an F1 transmission band and an F2 reception band, the ‘FT and ‘F2’ designations are arbitrary and are not intended to refer to any specific frequency bands or to indicate any particular relationship between frequencies (e.g., F1 may be greater than, or less than, F2). Moreover, for either FDD or TDD, the antenna architecture allows for F1 and F2 to be defined, and the associated transmit / receive chipsets (beamforming ICs) to be selected, with the only constraint being imposed by the antenna element bandwidth to which the chipsets are ultimately connected. Moreover, a similar architecture could be used for supporting more than one transmission band and / or more than one reception band. Nevertheless, it will be appreciated that the architecture described is particularly beneficial for providing an antenna system that is suitable for mmWave (or near mmWave) operation for which at least one of the frequency bands (F1 and / or F2) exceeds 10GHz (or more beneficially exceeds 20GHz, 25GHz, or even 30GHz).

[0059] Beneficially, as described in more detail later, the arrangement of diplexers 130 and the arrangement of beamforming ICs 112-1 on the beamforming board 112 are mutually configured to provide for a dual frequency architecture in a particularly compact, flexible, and efficient manner which allows for A / 2 spacing of antenna elements for mmWave frequency (albeit the architecture is not limited to such frequencies). The architecture may be configured to support FDD operation, or simultaneous (and independent / unsynchronised) transmitter / receiver operation in the different bands. The architecture may be configured to support multi-band TDD operation. The architecture beneficially allows for bands (F1 and F2) that are adjacent (or near adjacent) to be supported by means of using filters that are more selective for those frequencies (e.g., by increasing the length of the diplexers, and hence the dimension of the antenna structure in a direction perpendicular to the surface of the antenna array). Ridged Waveguide Diplexers

[0060] One possible arrangement of diplexers that may be used in the antenna system 100 of Figures 1 to 4 will now be described, by way of example only, with reference to Figures 5 to 9.

[0061] Figure 5 is an exploded view of an antenna array, and an arrangement of diplexers. Figure 6 shows the antenna array, and arrangement of diplexers of Figure 5 in an assembled form. Figure 7 is an exploded view of the antenna array and the arrangement of diplexers of Figure 5 together with a diplexer housing.

[0062] It will be appreciated that the antenna array, arrangement of diplexers, and diplexer housing shown in Figures 5 to 7 correspond generally to the corresponding parts of the antenna system of Figures 1 to 4.

[0063] Referring firstly to Figures 5, 6 and 7 in this example an arrangement of diplexers 530 is formed of ridged waveguide diplexers. Specifically, in this example, the arrangement diplexers 530 respectively comprises, for each antenna element 516-xy of an antenna array 516, a corresponding ridged waveguide diplexer pair 530-xy comprising two orthogonally arranged ridged waveguide diplexers (one for each polarisation).

[0064] As seen in Figure 5, in the antenna array 530, each antenna element 516-xy has, on its rear side (opposite a transmitting / receiving (or ‘radiating’) surface of the antenna element), a respective recess 532-xy. Each recess 532-xy is respectively configured for receiving and mechanically engaging with both ridged waveguide diplexers, of the corresponding ridged waveguide diplexer pair 530-xy, and for providing the necessary communicative coupling between the ridged waveguide diplexers and a radiating portion of that antenna element 516-xy. Thus, the arrangement of arrangement of diplexers 530 and antenna array 516 may be assembled to form an antenna array diplexer assembly as illustrated in Figure 6.

[0065] As seen in Figure 7, the arrangement of diplexers 530 may be received in an appropriate diplexer housing 514, e.g., as part of the antenna system 100 shown in Figures 1 to 4.

[0066] Figure 8 illustrates, in more detail, a diplexer pair, coupled to a corresponding antenna element, that may be used as a unit part of the arrangement of diplexers shown in Figures 5 to 7. As seen in Figure 8, each ridged waveguide diplexer pair 530-xy comprises a vertical polarisation ridged waveguide diplexer 530V-xy, and a horizontal polarisation ridged waveguide diplexer 530H-xy. It will be appreciated that whilst the ridged waveguide diplexers 530H-xy, 530V-xy, are referred to as being ‘horizontal polarisation’ and 'vertical polarisation’ for ease of description, the polarisation for each ridged waveguide diplexer 530H-xy, 530V-xy will depend on the orientation of the ridged waveguide diplexer pair 530-xy. For example, if the antenna element 516-xy (and ridged waveguide diplexer pair 530-xy located in it) is rotated by 90° about an axis that extends through the centre of the antenna element 516-xy perpendicular to a radiating surface 520 of the antenna element 516-xy then the vertical / horizontal polarisation associated with the ridged waveguide diplexers 530H-xy, 530V-xy, will be reversed.

[0067] The horizontal ridged polarisation ridged waveguide diplexer 530H-xy has a pair of elongate filter arms 530HFi-xy, 530HF2-xy that extend generally parallel to one another (from the antenna array 530 towards the beamforming board when the antenna system is assembled). One filter arm 530HFi-xy is configured to filter for allowing the F1 frequency band, and one filter arm 530HF2-xy corresponding to filter for allowing the F2 frequency band. The filter arms 530HFi-xy, 530HF2-xy of the horizontal polarisation ridged waveguide diplexer 530H-xy are connected to one another at one end by a connecting portion 534H-xy that extends perpendicularly to the filter arms 530HFi-xy, 530HF2-xy and connects them to a common port 536H-xy for the horizontal polarisation ridged waveguide diplexer 530H-xy. The common port 536H-xy of the horizontal polarisation ridged waveguide diplexer 530H-xy extends perpendicularly from an opposite side of the corresponding connecting portion 534H-xy to (in a direction away from) the filter arms 530HFi-xy, 530HF2-xy.

[0068] Similarly, the vertical polarisation ridged waveguide diplexer 530V-xy has a pair of elongate filter arms 530VFi-xy, 530VF2-xy that extend generally parallel to one another. One filter arm 530HFi-xy is configured to filter for allowing the F1 frequency band, and one filter arm 530HF2-xy corresponding to filter for allowing the F2 frequency band. The filter arms 530VFi-xy, 530VF2-xy of the vertical polarisation ridged waveguide diplexer 530V-xy are connected to one another at one end by a connecting portion 534V-xy that extends perpendicularly to the filter arms 530VFi-xy, 530VF2-xy and connects them to a common port 536V-xy for the vertical polarisation ridged waveguide diplexer 530V- xy. The common port 536V-xy of the vertical polarisation ridged waveguide diplexer 530V-xy extends perpendicularly from an opposite side of the corresponding connecting portion 534V-xy to (in a direction away from) the filter arms 530VFi-xy, 530VF2-xy.

[0069] The filter arms 530HFi-xy, 530HF2-xy, 530VFi-xy, 530VF2-xy are configured to extend in a direction generally perpendicular to a radiating surface of the antenna element 516-xy (and hence to the plane of the antenna array), when the ridged waveguide diplexer pair 530-xy is in position in the recess 532-xy of the corresponding antenna element 516-xy. The common ports 536H-xy, 536V-xy, are configured for engaging in the recess 532-xy, of the corresponding antenna element 516-xy, for providing the necessary communicative coupling between the ridged waveguide diplexers 536H-xy, 536V-xy, and a radiating portion of that antenna element 516-xy.

[0070] The vertical polarisation ridged waveguide diplexer 530V-xy and horizontal polarisation ridged waveguide diplexer 530H-xy of each ridged waveguide diplexer pair 530-xy are arranged orthogonally relative to one another, with their respective connecting portions 534V-xy, 534H-xy crossing one above the other at a generally central location on the connecting portions 534V-xy, 534H-xy. To facilitate this, one of the common ports - in this example the common port 536V-xy of the vertical polarisation ridged waveguide diplexer 530V-xy - is longer than the other (although it will be appreciated that either one could be the longer). Hence the connecting portion 534V-xy of the vertical polarisation ridged waveguide diplexer 530V-xy is further away from the corresponding antenna element 516-xy than the connecting portion 534H-xy of the horizontal polarisation ridged waveguide diplexer 530H-xy, when the ridged waveguide diplexer pair 530-xy is in position in the recess 532-xy of the corresponding antenna element 516-xy. This therefore allows a particularly compact arrangement of two ridged waveguide diplexers for different respective polarisations.

[0071] The width of each ridged waveguide diplexer 530H-xy or 530V-xy ( / .e., the distance between the outer edges of the corresponding filter arms 530HFi-xy, 530HF2-xy or 530Fi-xy, 530VF2-xy) is no greater than (and typically less than) half the wavelength (A / 2) of the highest frequency of operation of the antenna array 530. This allows the cross-sectional footprint of each ridged waveguide diplexer pair 530-xy in a plane perpendicular to the filter arms 530HFi-xy, 530HF2-xy, 530VFi-xy, 530VF2-xy (i . e. , in a plane parallel to that of the radiating surface of the antenna array) to be smaller than that of the antenna element and hence the antenna array 530 can meet the A / 2 requirement. As seen in Figure 6, when the arrangement of ridged waveguide diplexers 530 are assembled in the antenna array 516, the ridged waveguide diplexer pairs 530-xy in adjacent antenna elements 516-xy are mirrored relative to one another in both the H- polarisation and the V-Polarisation directions. Accordingly, there are 2 x 2 groupings of antenna elements 516-xy within the antenna array 516 that will have a common attribute that the outermost filter arms (i.e., nearest an outer edge or perimeter of the 2 x 2 grouping) will be associated with the same frequency band (which may be F1 or F2 depending on what the 2 x 2 grouping is centred on). Similarly, there are 2 x 2 groupings of antenna elements 516-xy within the antenna array 516 that have the common attribute that the innermost filter arms (i.e., facing one another and located nearest a centre of the 2 x 2 grouping) will be associated with the same frequency band (F2 or F1). As will be explained in more detail later, this is particularly beneficial for providing efficient connectivity with the beamforming chipsets.

[0072] It will be appreciated that whilst, in the illustrated example, the ridged waveguide diplexer pairs 530-xy in adjacent antenna elements 516-xy are mirrored relative to one another to provide the above common attributes for a given 2 x 2 group of antenna elements 516-xy, a similar effect could be achieved by other arrangements. For example, similar common attributes may be achieved by an arrangement on which, for any given 2 x 2 group of antenna elements 516-xy, each ridged waveguide diplexer pair 530-xy is rotated a quarter-turn relative to the ridged waveguide diplexer pairs 530- xy located in adjacent antenna elements 516-xy of that 2 x 2 group. Specifically, starting with the antenna element in one corner of a 2 x 2 group and sequentially proceeding in a clockwise (or anti-clockwise) direction for each antenna element 516- xy of that group, the ridged waveguide diplexer pair 530-xy located in one antenna element 516-xy is sequentially rotated by 90° (about its central longitudinal axis) compared to the ridged waveguide diplexer 530-xy in the preceding antenna element 516-xy.

[0073] It will be appreciated that the ridged waveguide diplexers 530-xy of suitable dimensions may be manufactured in any suitable way. The ridged waveguide diplexers 530-xy may, for example, be manufactured using 3D printing, possibly using an appropriately patterned frequency selective coating / surface. Specifically, to manufacture a ridged waveguide diplexer with small enough dimensions to support the desired frequencies a dielectric material having an appropriate dielectric constant is selected to ensure that the waveguide can be made small enough to meet the specific lattice dimensions dictated by the dense array operation. For example, where the lower frequency (fmin) is 24Ghz and the maximum frequency (fmax) is 30GHz ( / .e., a ratio of 1 .25) a dielectric constant of around 10 is appropriate. Nevertheless, it will be appreciated that other aspects such as the interconnections with the beamformer board and the antenna elements may also influence this choice. An appropriate 3D printing technology, e.g., that allows printing using plastic polymers and / or ceramic materials, may be used to achieve the necessary level of accuracy. Injection moulding is also a viable option albeit limited to the use of polymers. Polymers typically exhibit higher losses compared to ceramic materials, but have the benefits of being more flexible and of facilitating adherence to the interfaces, and hence providing more reliable connectivity

[0074] Figure 9 illustrates, an individual antenna element that may be used as a unit part of the antenna array shown in Figures 5 to 7.

[0075] As mentioned above, and as seen in Figure 9, each antenna element 516-xy includes a recess 532-xy configured for receiving and mechanically engaging with both ridged waveguide diplexers 530H-xy, 530V-xy, of a corresponding ridged waveguide diplexer pair 530-xy. Specifically, the recess 532-xy comprises a first waveguide engagement portion 532H-xy configured to receive the common port 536H-xy of the horizontal polarisation ridged waveguide diplexer 530H-xy, and a second ridged waveguide engagement portion 532V-xy configured to receive the common port 536V-xy of the vertical polarisation ridged waveguide diplexer 530V-xy. These waveguide engagement portions 532H-xy, 532V-xy are also configured to maintain the corresponding ridged waveguide diplexers 530H-xy, 530V-xy, in their orthogonal arrangement relative to one another. Each antenna element 516-xy also comprises respective coupling portions 540 (only one of which is visible), in the recess 532-xy, that are each arranged to provide a communicative coupling between at least one radiative portion of the antenna element 540 and a respective ridged waveguide diplexer 530H-xy, 530V-xy. It will be appreciated that the antenna element may comprise a single broadband radiating portion or may have a dual-band pair of radiating portions each of which is, effectively, coupled to a different respective filter arm of the diplexer.

[0076] Substrate Integrated Waveguide (SIW) Diplexers

[0077] Another possible arrangement of diplexers that may be used in the antenna system 100 of Figures 1 to 4 will now be described, by way of example only, with reference to Figures 10 and 11.

[0078] Figure 10 shows the antenna array, and an arrangement of diplexers in an assembled form. Figure 11 illustrates, in more detail, a diplexer pair, coupled to a corresponding antenna element, that may be used as a unit part of the arrangement of diplexers shown in Figure 10.

[0079] It will be appreciated that the antenna array, arrangement of diplexers, and diplexer housing shown in Figures 10 and 11 correspond generally to the corresponding parts of the antenna system of Figures 1 to 4.

[0080] Referring firstly to Figure 10 in this example an arrangement of diplexers 1030 is formed of substrate integrated waveguide (SIW) diplexers. Specifically, in this example, the arrangement diplexers 1030 respectively comprises, for each antenna element 1016-xy of an antenna array 1016, a corresponding SIW diplexer pair 1030- xy comprising two orthogonally arranged SIW diplexers (one for each polarisation).

[0081] The use of SIW technology allows the formation of appropriate filters, with the small dimensions (miniaturisation) necessary for the complex geometry, on the specific dielectric selected. As described in more detail below, the specific design, in which each individual SIW board has a high pass filter on one side and low pass filter on the other side, allows for the filters to be joined as a diplexer relatively easily whilst also allowing creation of an appropriate orthogonal structure (for supporting dual polarization) in which two SIW boards cross one another orthogonally without causing significant interference.

[0082] In the antenna array 1030, each antenna element 1016-xy has, on its rear side (opposite a transmitting / receiving (or ‘radiating’) surface of the antenna element), a respective waveguide engaging portion 1032-xy. Each waveguide engaging portion 1032-xy is respectively configured for receiving and mechanically engaging with both SIW diplexers, of the corresponding SIW diplexer pair 1030-xy, and for providing the necessary communicative coupling between the SIW diplexers and a radiating portion of that antenna element 1016-xy. Thus, the arrangement of arrangement of diplexers 1030 and antenna array 1016 may be assembled to form an antenna array diplexer assembly as illustrated in Figure 10.

[0083] The arrangement of diplexers 1030 may be received in an appropriate diplexer housing 1014, e.g., as part of the antenna system 100 shown in Figures 1 to 4 in a similar manner to that described for the arrangement of ridged waveguide diplexers described with reference to Figs. 5 to 9. Figure 11 illustrates, in more detail, a diplexer pair, coupled to a corresponding antenna element, that may be used as a unit part of the arrangement of diplexers shown in Figure 10.

[0084] As seen in Figure 11 , each SIW diplexer pair 1030-xy comprises a horizontal polarisation SIW diplexer 1030H-xy formed in a first elongate generally rectangular dielectric substrate portion (e.g., a section of PCB or the like), and a vertical polarisation SIW diplexer 1030V-xy formed in a second elongate generally rectangular dielectric substrate portion (e.g., a section of PCB or the like). It will be appreciated that whilst the SIW diplexers 1030H-xy, 1030V-xy, are referred to as being ‘horizontal polarisation’ and ‘vertical polarisation’ for ease of description, the polarisation for each SIW diplexer 1030H-xy, 1030V-xy will depend on the orientation of the SIW diplexer pair 1030-xy. For example, if the antenna element 1016-xy (and SIW diplexer pair 1030-xy located in it) is rotated by 90° about an axis that extends through the centre of the antenna element 1016-xy perpendicular to a radiating surface 1020 of the antenna element 1016-xy then the vertical / horizontal polarisation associated with the SIW diplexers 1030H-xy, 1030V-xy, will be reversed.

[0085] The horizontal polarisation SIW diplexer 1030H-xy has a pair of filter portions 1030HFi- xy, 1030HF2-xy (albeit only one - filter portion 1030HFi-xy - is visible in Figure 11). The pair of filter portions 1030HFi-xy, 1030HF2-xy are arranged adjacent (and generally parallel) one another in the first substrate portion on either side of its central longitudinal axis. One filter portion 1030HFi-xy is configured to filter for allowing the F1 frequency band, and one filter portion 1030HF2-xy corresponding to filter for allowing the F2 frequency band. The filter portions 1030HFi-xy, 1030HF2-xy of the horizontal polarisation SIW diplexer 1030H-xy are connected to one another at one end by a connecting portion 1034H-xy that connects them to a common port for the horizontal polarisation SIW diplexer 1030H-xy. The common port (not visible in Figure 11) of the horizontal polarisation SIW diplexer 1030H-xy extends perpendicularly from the corresponding connecting portion 1034H-xy to (in a direction away from) the filter portions 1030HFi-xy, 1030HF2-xy.

[0086] Similarly, the vertical polarisation SIW diplexer 1030V-xy has a pair of filter portions 1030VFi-xy, 1030VF2-xy (albeit only one - filter portion 1030F2-xy - is visible in Figure 11). The pair of filter portions 1030Vn-xy, 1030VF2-xy are arranged adjacent (and generally parallel) one another in the first substrate portion on either side of its central longitudinal axis. One filter portion 1030VFi-xy is configured to filter for allowing the F1 frequency band, and one filter portion 1030VF2-xy corresponding to filter for allowing the F2 frequency band. The filter portions 1030VFi-xy, 1030VF2-xy of the vertical polarisation SIW diplexer 1030V-xy are connected to one another at one end by a connecting portion 1034V-xy that connects them to a common port 1036V-xy for the vertical polarisation SIW diplexer 1030V-xy. The common port 1036V-xy of the vertical polarisation SIW diplexer 1030V-xy extends perpendicularly from the corresponding connecting portion 1034V-xy to (in a direction away from) the filter portions 1030VFI- xy, 1030VF2-xy.

[0087] The first and second substrate portions, in which the filter portions 1030HFi-xy, 1030HF2-xy, 1030VFi-xy, 1030VF2-xy are formed, are configured to extend in a direction generally perpendicular to a radiating surface of the antenna element 1016-xy (and hence to the plane of the antenna array), when the SIW diplexer pair 1030-xy is in position in a plurality of clips 1038V-xy, 1038H-xy provided within the waveguide engaging portion (not shown in Figure 11 for simplicity) of the corresponding antenna element 1016-xy. At least a subset of the clips 1038V-xy, 1038H-xy are coupling clips configured for providing a communicative coupling to a radiating portion of that antenna element 1016-xy. The common ports are configured for engaging in respective coupling clips 1038V-xy, 1038H-xy and hence couple the SIW diplexers 1036H-xy, 1036V-xy, to the radiating portion of that antenna element 1016-xy.

[0088] The vertical polarisation SIW diplexer 1030V-xy and horizontal polarisation SIW diplexer 1030H-xy of each SIW diplexer pair 1030-xy are assembled in an orthogonal arrangement relative to one another, with their respective substrate portions crossing one above the other at their generally central longitudinal axes. To facilitate this, the substrate portions may be slotted along part of their generally central longitudinal axes in a manner that allows each substrate portion to be slidably received in the slot of the other to form the orthogonal arrangement as seen in Figure 11.

[0089] The width of each SIW diplexer 1030H-xy or 1030V-xy ( / .e., the distance between the outer edges of the corresponding substrate portions) is no greater than (and typically less than) half the wavelength (A / 2) of the highest frequency of operation of the antenna array 1030. This allows the cross-sectional footprint of each SIW diplexer pair 1030-xy in a plane perpendicular to both substrate portions (i.e. , in a plane parallel to that of the radiating surface of the antenna array) to be smaller than that of the antenna element and hence the antenna array 1030 can meet the A / 2 requirement.

[0090] As seen in Figure 10, when the arrangement of SIW diplexers 1030 is assembled in the antenna array 1016, for any given 2 x 2 group of antenna elements 1016-xy, each SIW diplexer pair 1030-xy is rotated a quarter-turn relative to the SIW diplexer pairs 1030-xy located in adjacent antenna elements 1016-xy of that 2 x 2 group. Specifically, starting with the antenna element in one corner of a 2 x 2 group and sequentially proceeding in a clockwise (or anti-clockwise) direction for each antenna element 1016- xy of that group, the SIW diplexer pair 1030-xy located in one antenna element 1016- xy is sequentially rotated by 90° (about its central longitudinal axis) compared to the SIW diplexer pair 1030-xy in the preceding antenna element 1016-xy.

[0091] Accordingly, there are 2 x 2 groupings of antenna elements 1016-xy within the antenna array 1016 that will have a common attribute that the outermost filter arms (i.e., nearest an outer edge or perimeter of the 2 x 2 grouping) will be associated with the same frequency band (which may be F1 or F2 depending on what the 2 x 2 grouping is centred on). Similarly, there are 2 x 2 groupings of antenna elements 1016-xy within the antenna array 1016 that will have a common attribute that the innermost filter portions (i.e., facing one another and located nearest a centre of the 2 x 2 grouping) will be associated with the same frequency band (F2 or F1). As will be explained in more detail later, this is particularly beneficial for providing efficient connectivity with the beamforming chipsets.

[0092] Nevertheless, it will be appreciated that a similar effect could be achieved by other arrangements. For example, similar common attributes may be achieved using an arrangement, similar to that seen in Figure 6 for ridged waveguide diplexers, in which the SIW diplexer pairs 1030-xy in adjacent antenna elements 1016-xy of a 2 x 2 group of antenna elements 1016-xy are mirrored relative to one another in both the H- polarisation and the V-Polarisation directions.

[0093] It will be appreciated that the SIW diplexers 1030-xy of suitable dimensions may be manufactured in any suitable way. The SIW diplexers 1030-xy may, for example, be manufactured using a semi-additive process (SAP) additive manufacturing process that provides the accuracy required for the SIW filter substrates (e.g., using an Averatek™ Semi-Additive Process (A-SAP™)).

[0094] It will also be appreciated that, whilst the described structure comprises a lattice of separate pairs of SIW boards repeated across the array, a similar effect could be achieved with multiple filter elements being provided on a single PCB spanning multiple antenna elements (e.g., extending across the whole array). For example, the separate boards of adjacent horizontal SIW diplexers in a given row (and / or adjacent vertical SIW diplexers in a given column) may be replaced by one or more boards forming two or more horizontal SIW diplexers (and / or two or more vertical SIW diplexers). It can be seen that this might result, for the specific example illustrated in Figure 10, with eight separate PCB boards for the horizontal polarization diplexers and eight separate PCB boards for the vertical polarization diplexers.

[0095] Connectivity to Radiating Portions of Antenna Elements

[0096] Possible connectivity between the diplexers and the radiating portions of the antenna elements that may be used in the antenna system 100 of Figures 1 to 4 will now be described, by way of example only, with reference to Figures 12 and 13.

[0097] Figure 12 illustrates, schematically, possible diplexer to radiating element connectivity for antenna elements comprising broadband radiating elements.

[0098] As seen in Figure 12, a simplified cross-sectional view of part of an antenna system 1200 (e.g., part of the antenna system 100 of Figures 1 to 4) is shown. The illustrated part of the antenna system 1200 includes an antenna array 1216 and an arrangement of diplexers 1230 in an assembled form.

[0099] The antenna array 1216 comprises a plurality of individual antenna elements 1216-xy (which may form part of a larger array as described earlier) each of which, in this example, is a broadband antenna element configured both for transmission via that antenna element in (at least) the first frequency band (F1) and for reception via that antenna element in (at least) the second frequency band (F2). To this end, each antenna element 1216-xy comprises a broadband radiating portion / element 1220-xy on a transmission / reception side of the antenna element. It will be appreciated that the broadband radiating portion / element 1220-xy may, for example, be an annular element provided on the transmission / reception surface of the antenna element (i.e., in a plane perpendicular to the page) as illustrated at insert (a).

[0100] It will be appreciated that the antenna elements may, for example, correspond to those referred to with reference to Figures 1 to 4, 5 to 9, or 10 and 11.

[0101] The arrangement of diplexers 1230 respectively comprises, for each antenna element 1216-xy of the antenna array 1216, a corresponding diplexer pair 1230-xy comprising two orthogonally arranged diplexers (one for each polarisation).

[0102] Each diplexer pair 1230-xy is coupled to the corresponding antenna element 1216-xy and comprises a horizontal polarisation diplexer 1230H-xy, and a vertical polarisation diplexer 1230V-xy. It will be appreciated that whilst the diplexers 1230H-xy, 1230V-xy, are referred to as being ‘horizontal polarisation’ and ‘vertical polarisation’ for ease of description, the polarisation for each diplexer 1230H-xy, 1230V-xy will depend on the orientation of the diplexer pair 1230-xy as described earlier. It will be appreciated that the diplexers 1230H-xy, 1230VH-xy illustrated in Figure 12 may be ridge waveguide diplexers (e.g., similar to, or the same as, those described in relation to Figures 5 to 9) or SIW diplexers (e.g., similar to, or the same as, those described in relation to Figures W and 11).

[0103] The horizontal polarisation diplexer 1230H-xy has a pair of filter portions 1230HFi-xy, 1230HF2-xy. One filter portion 1230HFi-xy is configured to filter for allowing the F1 frequency band, and one filter portion 1230HF2-xy corresponding to filter for allowing the F2 frequency band. The filter portions 1230HFi-xy, 1230HF2-xy of the horizontal polarisation diplexer 1230H-xy are connected to one another by a connecting portion 1234H-xy that connects them to a common port 1236H-xy for the horizontal polarisation diplexer 1230H-xy. The common port 1236H-xy of the horizontal polarisation diplexer 1230H-xy is arranged to provide a communicative coupling between the broadband radiating portion / element 1220-xy and the filter portions 1230HFi-xy, 1230HF2-xy.

[0104] It will be appreciated that, in a similar manner, the vertical polarisation diplexer 1230V- xy will have a pair of filter portions (one for each of the F1 and F2 frequency bands) connected to one another by a connecting portion that connects them to a common port 1236V-xy that is arranged to provide a communicative coupling between the broadband radiating portion / element 1220-xy and those filter portions.

[0105] It will be appreciated that the diplexers 1230H-xy, 1230VH-xy illustrated in Figure 12 may be ridge waveguide diplexers (e.g., similar to, or the same as, those described in relation to Figures 5 to 9) or SIW diplexers (e.g., similar to, or the same as, those described in relation to Figures 10 and 11).

[0106] Figure 13 illustrates, schematically, possible diplexer to radiating element connectivity for antenna elements comprising dual-band radiating elements.

[0107] As seen in Figure 13, a simplified cross-sectional view of part of an antenna system 1300 (e.g., part of the antenna system 100 of Figures 1 to 4) is shown. The illustrated part of the antenna system 1300 includes an antenna array 1316 and an arrangement of diplexers 1330 in an assembled form. The antenna array 1316 comprises a plurality of individual antenna elements 1316-xy (which may form part of a larger array as described earlier) each of which, in this example, is a dual-band or multi-band compatible antenna element. To this end, each antenna element 1316-xy comprises at least one F1 frequency band radiating portion / element 1320Fi-xy, and at least one F2 frequency band radiating portion / element 1320p2-xy, on a transmission / reception side of the antenna element. It will be appreciated that each radiating portion / element 1320pi-xy, 1320p2-xy may, for example, be an annular element provided on the transmission / reception surface of the antenna element (i.e., in a plane perpendicular to the page) as illustrated at insert (a). It will be appreciated that the antenna elements may, for example, correspond to those referred to with reference to Figures 1 to 4, 5 to 9, or 10 and 11.

[0108] The arrangement of diplexers 1330 respectively comprises, for each antenna element 1316-xy of the antenna array 1316, a corresponding diplexer pair 1330-xy comprising two orthogonally arranged diplexers (one for each polarisation).

[0109] Each diplexer pair 1330-xy is coupled to the corresponding antenna element 1316-xy and comprises a horizontal polarisation diplexer 1330H-xy, and a vertical polarisation diplexer 1330V-xy. It will be appreciated that whilst the diplexers 1330H-xy, 1330V-xy, are referred to as being ‘horizontal polarisation’ and ‘vertical polarisation’ for ease of description, the polarisation for each diplexer 1330H-xy, 1330V-xy will depend on the orientation of the diplexer pair 1330-xy as described earlier. It will be appreciated that the diplexers 1330H-xy, 1330VH-xy illustrated in Figure 13 may be ridge waveguide diplexers (e.g., similar to, or the same as, those described in relation to Figures 5 to 9) or SIW diplexers (e.g., similar to, or the same as, those described in relation to Figures W and 11).

[0110] The horizontal polarisation diplexer 1330H-xy has a pair of filter portions 1330HFi-xy, 1330HF2-xy. One filter portion 1330HFi-xy is configured to filter for allowing the F1 frequency band, and one filter portion 1330HF2-xy corresponding to filter for allowing the F2 frequency band. In this example, each filter portion 1330HFi-xy, 1330HF2-xy of the horizontal polarisation diplexer 1330H-xy is respectively connected to a corresponding one of the radiating portion / elements 1320Fi-xy, 1320F2-xy by an appropriate communicative coupling.

[0111] It will be appreciated that, in a similar manner, the vertical polarisation diplexer 1330V- xy will have a pair of filter portions (one for each of the F1 and F2 frequency bands) that are respectively connected to a corresponding one of the radiating portion / elements 1320Fi-xy, 1320F2-xy by an appropriate communicative coupling.

[0112] It will be appreciated that the diplexers 1330H-xy, 1330VH-xy illustrated in Figure 13 may be ridge waveguide diplexers (e.g., similar to, or the same as, those described in relation to Figures 5 to 9) or SIW diplexers (e.g., similar to, or the same as, those described in relation to Figures 10 and 11).

[0113] Connectivity to Beam forming ICs

[0114] Possible connectivity between the diplexers and the beamforming ICs that may be used in the antenna system 100 of Figures 1 to 4 will now be described, by way of example only, with reference to Figures 14 to 19.

[0115] Figure 14 illustrates an arrangement of connection ports in a section of a beamformer board, for providing communicative connectivity between a ridged waveguide diplexer pair, of the type illustrated in Figure 8, and corresponding beamforming transmitter, receiver and / or transceiver ICs. Figure 15 illustrates, in more detail, a ridge waveguide diplexer to beamformer board transition for the section of the beamformer board illustrated in Figure 14. Figure 16 illustrates how the arrangement of connection ports shown in Figure 14 may be extended for providing communicative connectivity between an array of ridged waveguide diplexer pairs, of the type illustrated in Figure 8, and corresponding beamforming transmitter, receiver and / or transceiver ICs.

[0116] Referring to Figure 14, a section 1410 of the beamformer board (e.g., a beamformer board 112 as shown in Figures 1 to 4) is shown connected to a corresponding ridged waveguide diplexer pair 530-xy, of the type illustrated in Figure 8, comprising a vertical polarisation ridged waveguide diplexer 530V-xy, and a horizontal polarisation ridged waveguide diplexer 530H-xy.

[0117] The beamformer board section 1410 comprises a plurality of connection ports 1450Vn, 1450VF2, 1450HFI , 1450HF2for providing communicative connectivity between the ridged waveguide diplexer pair 530-xy and corresponding beamforming transmitter, receiver and / or transceiver ICs. The plurality of connection ports 1450FI , 1450VF2, 1450Hn, 1450HF2include: a first connection port 1450Vn for providing communicative connectivity between an F1 band filter arm 530VFi-xy of the vertical polarisation ridged waveguide diplexer 530V-xy, and a corresponding beamforming IC; a second connection port 1450VF2 for providing communicative connectivity between an F2 band filter arm 530VF2-xy of the vertical polarisation ridged waveguide diplexer 530V-xy, and a corresponding beamforming IC; a third connection port 1450Hn for providing communicative connectivity between an F1 band filter arm 530HFi-xy of the horizontal polarisation ridged waveguide diplexer 530H-xy, and a corresponding beamforming IC; and a fourth connection port 1450HF2for providing communicative connectivity between an F2 band filter arm 530HF2-xy of the horizontal polarisation ridged waveguide diplexer 530H-xy, and a corresponding beamforming IC.

[0118] As seen in Figure 15, which shows the underside of the beamformer board section 1410 shown in Figure 14, a plurality of transition structures 1452VFI , 1452VF2, 1452Hn, 1452HF2 are provided in the board section 1410 to provide the transition between each filter arm 530VFi-xy, 530VF2-xy, 530HFi-xy, 530HF2-xy and its respective connection port 1450VFi, 1450VF2, 1450HFI , 1450HF2. AS illustrated in the more detailed enlarged view of the transition structure 1452VF2 (for providing the transition between the F2 band filter arm 530VF2-xy of the vertical polarisation ridged waveguide diplexer 530V- xy and the second connection port 1450VF2), each transition structure 1452Vn, 1452VF2, 1452HFI , 1452HF2(in the illustrated example), respectively comprises a first plurality of vias 1454 (in the example 4) and at least one further via 1456. The first plurality of vias 1454 are each provided through a first layer of the beamforming board 1410 for providing connectivity between the corresponding diplexer filter arm 530VFr xy, 530VF2-xy, 530HFi-xy, 530HF2-xy and an interface between the first and a second layer of the beamforming board 1410. Each further via 1456 is provided through a second layer of the beamforming board 1410 for providing connectivity between the interface between the first and the second layer of the beamforming board 1410, and the corresponding connection port.

[0119] Referring to Figure 16, a larger section 1610 of the beamformer board (e.g., a beamformer board 112 as shown in Figures 1 to 4) is shown that corresponds to a 2 x 2 group of antenna elements and associated ridged waveguide diplexer pairs 530-xy. Accordingly, the larger beamformer board section 1610 comprises four sub-sections 1410-1, 1410-2, 1410-3, 1410-4 each sub-section being essentially the same as the beamformer board section 1410 described with reference to Figures 14 and 15. However, as seen in Figure 16 each sub-section 1410-1, 1410-2, 1410-3, 1410-4 is mirrored compared to the adjacent sub-sections (or rotated by 90° about the generally central longitudinal axis of the corresponding diplexer pair 530-xy compared to the adjacent sub-sections) because of the corresponding orientational relationship (mirrored / rotated) between the adjacent diplexer pairs 530-xy (and possibly the associated antenna elements) - for example as described with reference to Figure 6.

[0120] Accordingly, all connection ports 1450n for providing communicative connectivity between the F1 band filter arms of the ridged waveguide diplexer pairs 530-xy of the 2 x 2 group are all located at the outer perimeter of the group of connection ports 1450FI , 1450F2 ( / . e. , nearest an outer edge or peri meter of the larger beamformer board section 1610). Contrastingly, the connection ports 1450F2 for providing communicative connectivity between the F2 band filter arms of the ridged waveguide diplexer pairs 530-xy of the 2 x 2 group are all located nearest to the centre of the group of connection ports 1450FI , 1450F2 (i.e., located nearest a centre of the larger beamformer board section 1610). As mentioned earlier, this is particularly beneficial for providing efficient connectivity with the beamforming chipsets, as will now be explained in more detail with reference to Figures 17 to 19.

[0121] Figure 17 illustrates, schematically in plan, an interlaced arrangement of beamforming chipsets and their respective connectivity to the connection ports of each of a plurality of beamformer board sections of the type illustrated in Figures 14 to 16.

[0122] Specifically, Figure 17 illustrates how the arrangements of connection ports shown in Figures 14 and 16 can be used as component modules of a wider array to provide connectivity with beamforming ICs for each of a plurality of different frequency bands (e.g., F1 and F2).

[0123] As seen in Figure 17, a plurality of F1 beamforming chips / chipsets 1712FI , and a plurality of F2 beamforming chips / chipsets 1712F2, that are arranged on a beamforming board 1712 made up of a plurality of beamformer board sections 1410-1, 1410-2, 1410- 3, 1410-4 of the type illustrated in Figures 14 to 16. Specifically, the beamformer board comprises a plurality of 2 x 2 groupings of four beamformer sub-sections 1410-1 , 1410- 2, 1410-3, 1410-4 where, as described with reference to Figure 16, each sub-section is essentially the same as the beamformer board section 1410 described with reference to Figures 14 and 15. However, as seen in Figure 17 (an described earlier with reference to Figure 16) each sub-section 1410-1 , 1410-2, 1410-3, 1410-4 in a respective 2 x2 grouping is mirrored compared to the adjacent sub-sections (or rotated by 90° about the centre of that sub-section compared to the adjacent sub-sections). Accordingly, there are 2 x 2 groupings of beamformer board sub-sections 1410-1 , 1410-2, 1410-3, 1410-4 (e.g., the grouping (A), (B), (C), and (D)) for which the connection ports for providing F1 connectivity are all located nearest an outer edge or perimeter of those 2 x 2 groupings of beamformer board sub-sections 1410-1, 1410-2, 1410-3, 1410-4. Contrastingly, the connection ports for providing F2 connectivity of each of these groupings of beamformer board sub-sections 1410-1 , 1410-2, 1410-3, 1410-4 is respectively located nearest the centre of that 2 x 2 grouping.

[0124] Similarly, there are 2 x 2 groupings of beamformer board sub-sections 1410-1 , 1410- 2, 1410-3, 1410-4 (e.g., the grouping (D), (E), (F), and (G)) for which the connection ports for providing F2 connectivity are all located nearest an outer edge or perimeter of those 2 x 2 groupings of beamformer board sub-sections 1410-1 , 1410-2, 1410-3, 1410-4. Contrastingly, the connection ports for providing F1 connectivity of each of these groupings of beamformer board sub-sections 1410-1 , 1410-2, 1410-3, 1410-4 is respectively located nearest the centre of that 2 x 2 grouping. It will nevertheless be appreciated that these different 2 x 2 groupings overlap (e.g., beamformer sub-section (D) forms part of both the example groupings).

[0125] The F1 beamforming chips / chipsets 1712FI , and F2 beamforming chips / chipsets 1712F2, are arranged on the beamforming board 1712 relative to the 2 x 2 groupings of beamformer board sub-sections 1410-1, 1410-2, 1410-3, 1410-4, in an interlaced manner relative to one another, that beneficially provides efficient, near optimum, connectivity to the corresponding F1 and F2 connection ports.

[0126] Specifically, the F1 beamforming chips / chipsets 1712FI are arranged on the beamforming board 1712 such that each F1 beamforming chips / chipset 1712FI is generally centred at a position equidistant from the connection ports, of a corresponding 2 x 2 grouping of beamformer board sub-sections 1410-1 , 1410-2, 1410-3, 1410-4, for providing F1 connectivity. Similarly, the F2 beamforming chips / chipsets 1712F2 are arranged on the beamforming board 1712 such that each F2 beamforming chips / chipset 1712Fiis generally centred at a position equidistant from the connection ports, of a corresponding 2 x 2 grouping of beamformer board subsections 1410-1 , 1410-2, 1410-3, 1410-4, for providing F2 connectivity. In addition to the efficiency and scalability associated with positioning the beamforming chips / chipsets 1712FI , 1712F2in this way, this arrangement also helps to ensure that the various path lengths involved are near identical. Nevertheless, it will be appreciated that this arrangement is beneficial even if the beamforming chips / chipset are centred at positions that are near, but not exactly, equidistant from the corresponding connection ports.

[0127] Accordingly, it can be seen that the F1 beamforming chips / chipsets 1712Fiare arranged on the beamforming board 1712 such that each F1 beamforming chip / chipset 1712n is generally concentric with a corresponding 2 x 2 grouping (e.g., the grouping (D), (E), (F), and (G)) of beamformer board sub-sections 1410-1, 1410-2, 1410-3, 1410-4, for which the connection ports for providing F1 connectivity are all located nearest the centre of that grouping of beamformer board sub-sections 1410-1, 1410- 2, 1410-3, 1410-4.

[0128] Similarly, it can be seen that the F2 beamforming chips / chipsets 1712F2 are arranged on the beamforming board 1712 such that each F2 beamforming chip / chipset 1712FI is generally concentric with a corresponding 2 x 2 grouping (e.g., the grouping (A), (B), (C), and (D)) of beamformer board sub-sections 1410-1 , 1410-2, 1410-3, 1410-4, for which the connection ports for providing F2 connectivity are all located nearest the centre of that grouping of beamformer board sub-sections 1410-1, 1410-2, 1410-3, 1410-4.

[0129] In Figure 17, whilst the F1 beamforming chips / chipsets 1712FI are shown as being connected for transmission, and the F2 beamforming chips / chipsets 1712F2are shown as being connected for reception, it will be appreciated that the F1 and / or F2 beamforming chips / chipsets may be connected for transmission, reception, and / or for both transmission and reception.

[0130] It can be seen that the illustrated lattice architecture arrangement on the beamformer board beneficially contributes to providing the dual frequency diplexed architecture described in an efficient and effective manner.

[0131] Figure 18 illustrates, schematically in plan, an interlaced arrangement of transmitter and receiver beamforming chipsets, and their respective connectivity to diplexer pairs of the type illustrated in Figure 8, of a diplexer array as illustrated in Figures 5 to 7.

[0132] In the example of Figure 18, a plurality of transmitter beamformer chips 1812T and a plurality of receiver beamformer chips 1812R are shown forming part of a larger array of beamformer chips 1812T, 1812R (only part of which is shown). The transmitter beamformer chips 1812T may, for example, correspond to the F1 beamforming chips / chipsets 1712FI shown in Figure 17. Similarly, the receiver beamformer chips 1812RT may, for example, correspond to the F2 beamforming chips / chipsets 1712F2 shown in Figure 17.

[0133] Each beamformer chip 1812T, 1812R, is respectively, in this example, a dual polarization, four-ports, beamformer IC and may be the same type of transceiver beamformer IC configured for transmission or reception as shown.

[0134] As seen in Figure 18, each transmitter beamformer chip 1812T is respectively connected to the horizontal polarisation and the vertical polarisation filter arms 530HFI- xy, 530VFi-xy associated with a transmission frequency band (in this example F1) of each of four different diplexer pairs 530-xy. Similarly, each receiver beamformer chip 1812R is respectively connected to the horizontal polarisation and the vertical polarisation filter arms 530HF2-xy, 530VF2-xy associated with a receiver frequency band (in this example F2) of each of four different diplexer pairs 530-xy. The connectivity between the beamformer chips 1812T, 1812R and the diplexer pairs 530-xy may, for example, be provided via appropriate connection ports as described with reference to Figures 14 to 17.

[0135] Accordingly, each diplexer pair 530-xy (e.g., as described with reference to Figure 8) is respectively connected to one transmitter beamformer chip 1812T and one receiver beamformer chip 1812R.

[0136] It can be seen, therefore, that the connectivity described above, the arrangement of the connection ports and beamformer ICs, and the use of dual polarization, four-ports, beamformer ICs, can all contribute to achieving the necessary distribution of the signals whilst helping to ensure an inter-element spacing of A / 2 (or below) even for a very dense array.

[0137] It will be appreciated that whilst Figures 14 to 18 have been described, primarily, with reference to ridged waveguide diplexers and associated diplexer pairs described with reference to Figures 5 to 9, the connectivity described above, the arrangement of the connection ports and beamformer ICs, and the use of dual polarization, four-ports, beamformer ICs, may be adapted to other diplexer arrangements such as the SIW diplexer arrangement described with reference to Figures 10 and 11 .

[0138] Figure 19, for example, illustrates, schematically in plan, an interlaced arrangement of transmitter and receiver beamforming chipsets, and their respective connectivity to diplexer pairs of the type illustrated in Figure 11 , of a diplexer array as illustrated in Figure 9. In the example of Figure 19, a plurality of transmitter beamformer chips 1912T and a plurality of receiver beamformer chips 1912R are shown forming part of a larger array of beamformer chips 1892T, 1912R (only part of which is shown). The transmitter beamformer chips 1912T may, for example, correspond to the F1 beamforming chips / chipsets 1712FI shown in Figure 17. Similarly, the receiver beamformer chips 1912RT may, for example, correspond to the F2 beamforming chips / chipsets 1712F2 shown in Figure 17.

[0139] Each beamformer chip 1912T, 1912R, is respectively, in this example, a dual polarization, four-ports, beamformer IC and may be the same type of transceiver beamformer IC configured for transmission or reception as shown.

[0140] As seen in Figure 19, each transmitter beamformer chip 1912T is respectively connected to the horizontal polarisation and the vertical polarisation filter portions 1030HFi-xy, 1030VFi-xy associated with a transmission frequency band (in this example F1) of each of four different diplexer pairs 1030-xy. Similarly, each receiver beamformer chip 1812R is respectively connected to the horizontal polarisation and the vertical polarisation filter arms 1030HF2-xy, 1030VF2-xy, associated with a receiver frequency band (in this example F2) of each of four different diplexer pairs 1030-xy. The connectivity between the beamformer chips 1912T, 1912R and the diplexer pairs 1030-xy may, for example, be provided via appropriate connection ports 1050Hn-xy, 1050HF2-xy, 1050Vn-xy, 1050VF2-xy in a similar manner to that described with reference to Figures 14 to 17.

[0141] Accordingly, each diplexer pair 1030-xy (e.g., as described with reference to Figure 9) is respectively connected to one transmitter beamformer chip 1912T and one receiver beamformer chip 1912R.

[0142] The transmitter beamformer chips 1912T, and receiver beamformer chips 1912R, are arranged on the beamforming board relative to 2 x 2 groupings of diplexers 1030-xy (in this example SiW diplexers), in an interlaced manner relative to one another, that beneficially provides efficient, near optimum, connectivity to the corresponding F1 and F2 connection ports.

[0143] Specifically, the transmitter beamformer chips 1912T are arranged on the beamforming board such that each transmitter beamformer chip 1912T is generally centred at a position equidistant from the connection ports, of a corresponding 2 x 2 grouping of diplexer connection ports 1050HFi-xy, 1050VFi-xy for providing F1 connectivity. Similarly, the receiver beamformer chips 1912R are arranged on the beamforming board such that each receiver beamformer chip 1912R, is generally centred at a position equidistant from the connection ports, of a corresponding 2 x 2 grouping of diplexer connection ports 1050HF2-xy, 1050VF2-xy for providing F2 connectivity. In addition to the efficiency and scalability associated with positioning the beamforming chips / chipsets in this way, this arrangement also helps to ensure that the various path lengths involved are near identical. Nevertheless, it will be appreciated that this arrangement is beneficial even if the beamforming chips / chipset are centred at positions that are near, but not exactly, equidistant from the corresponding connection ports.

[0144] It can be seen, therefore, that the connectivity described above, the arrangement of the connection ports and beamformer ICs, and the use of dual polarization, four-ports, beamformer ICs, can all contribute to achieving the necessary distribution of the signals whilst helping to ensure an inter-element spacing of A / 2 (or below) even for a very dense array.

[0145] It will be appreciated that whilst Figure 19 has been described with reference to connectivity between the beamforming board and diplexer array, connectivity between the diplexer array and the antenna elements may be achieved in a similar manner.

[0146] Figure 20, for example, illustrates, schematically in plan, possible diplexer to radiating element connectivity for the diplexer array shown in Figure 19.

[0147] As seen in Figure 20, each vertical polarisation diplexer 1030V-xy is respectively provided with at least one vertical polarisation antenna feed connection 1060V-xy for connecting that diplexer to the radiating element of the corresponding antenna element 1016-xy. Similarly, horizontal polarisation diplexer 1030H-xy is respectively provided with at least one horizontal polarisation antenna feed connection 1060H-xy for connecting that diplexer to the radiating element of the corresponding antenna element 1016-xy. For each 2 x 2 group of antenna elements 1016-xy and diplexer pairs 1030- xy, the relative location of the vertical polarisation antenna feed connection 1060V-xy and horizontal polarisation antenna feed connection 1060H-xy for each diplexer pair 1030-xy is mirrored compared to the adjacent diplexer pairs 1030-xy (or rotated by 90° about the generally central longitudinal axis of the corresponding diplexer pair 1030- xy compared to the adjacent diplexer pairs 1030-xy) because of the corresponding orientational relationship (mirrored / rotated) between the adjacent diplexer pairs 1030- xy (and possibly the associated antenna elements) - for example as described with reference to Figure 10. Applications - Multi-beam Clusters and Sparse Arrays

[0148] Referring to Figure 21 , which illustrates, schematically, an application of the antenna architecture to provide a multi-beam cluster of antenna arrays, a plurality of antenna tiles 2100 (2100-1 , 2100-2, 2100-3), may be arranged in a cluster 2110 and configured to support multiple transmitter and / or receiver beams.

[0149] Each antenna tile 2100 in the cluster 2110 comprises, in this example, an antenna array, a diplexer array, and the associated arrangement of beamforming integrated circuits (ICs) and associated electronics as described above. Transmission and / or reception via each cluster 2110 may, beneficially, be controlled via a common transceiver platform 2172 such as, for example, a single software defined radio (SDR) or radio frequency system on a chip (RFSoC). Where necessary, the communication signals sent / received via each tile 2100 may be respectively subject to appropriate frequency conversion at an up / downconverter 2174 (e.g., with synchronisation control provided by a phase-locked loop (PLL) 2176). Nevertheless, it will be appreciated that such frequency conversion may not be necessary (e.g., for frequencies covered by the common transceiver platform 2172 such as the RFSoC). It will be appreciated that, in this example, each tile 2100 may support dual band and / or dual polarisation.

[0150] The tiles 2100 in the cluster 2110 may be arranged without the same restriction on the spacing between them as is imposed on the antenna elements within each tile 2100 (e.g., the spacing between arrays can be significantly greater than half the wavelength (A) - e.g., a plurality of integer multiples of A - at the highest frequency of operation, effectively forming a sparse array). Whilst, compared to dense arrays, sparse arrays are known to suffer from significant sidelobes, the ability to use each tile 2100 to generate a beam through analog beamforming in any specific direction, beneficially allows it to be used effectively in a sparse array because the analog beamforming can be used to reduce the sidelobes significantly (because the individual element radiation pattern has already suppressed the sidelobes outside the main lobe). The effect of the sidelobes can also be reduced by tapering techniques. Moreover, whilst compared to dense arrays, sparse arrays are known to suffer from grating lobes, these can be avoided - or at least minimised - be appropriate positioning (e.g., via randomising) of the tiles 2100.

[0151] As the tiles 2100 are clustered together, and there is no need to reduce the space between them provided that grating lobes are avoided appropriately (e.g., by accurate positioning / randomization of the tiles 2100 themselves), the cluster can be thus operated as a source of multiple beams 2170 (2170-1 , 2170-2, 2170-3) with a respective transmitter and / or receiver beam 2170 provided via each tile 2100. It will be appreciated that while three antenna tiles 2100 are shown there may be any suitable number ‘N’ of tiles 2100 forming a corresponding cluster 2110 to generate N corresponding transmitter beams and / or N corresponding receiver beams. It will be appreciated that each tile 2100 of each cluster2110 could additionally (or alternatively) operate in a different respective frequency band (i.e., not simply providing a different beam).

[0152] It can be seen that this clustered architecture also beneficially allows for a hybrid digital and analog approach in which digital beamforming may be performed within each analog beam for the purpose of increasing resolution and / or generating additional beams within the beamwidth of the analog beam created by a given tile 2100. For example, each tile 2100 can be configured to form a beam in a different respective direction using analog techniques and to form one or more beams within that directional analog beam using digital beamforming (i.e., to provide multiple beams and / or at least one beam pointing in at least one corresponding very specific direction with a high degree of accuracy). As the tiles, themselves, may be arranged sparsely as a sparse array, this may be thought of as being analogous to the scenario in radioastronomy in which a dish may be physically pointed in a specific direction and the resolution enhanced by collecting synchronous data from multiple sparse dishes.

[0153] The use of sparse arrays in this way also has the benefit that it allows more space to be provided behind the elements and clusters, e.g., for provision of the common transceiver platform 2172 (SDR or RFSoC) (as mentioned above) to support hybrid beamforming.

[0154] Multiple clusters, such as those described with reference to Figure 21 may be arranged together to provide a larger sparse array configuration for improved beamwidth and accuracy through digital beamforming. Figure 22, for example, illustrates, schematically, an arrangement of a plurality of clusters multi-beam clusters of the type described with reference to Figure 21.

[0155] As seen in Figure 22, in the illustrated example three clusters 2210 (2210-10, 2210- 20, and 2210-30) are provided. Each cluster 2210 comprises a respective plurality of antenna tiles 2120 (2200-11 to 2200-33) configured to support multiple transmitter and / or receiver beams as described with reference to Figure 21. Each antenna tile 2200 in the cluster 2210 comprises, in this example, an antenna array, a diplexer array, and the associated arrangement of beamforming integrated circuits (ICs) and associated electronics as described above.

[0156] Transmission and / or reception via each cluster 2210 may, beneficially, be controlled via a respective common transceiver platform 2172 (2172-10, 2172-20, and 2172-30) such as, for example, a respective software defined radio (SDR) or radio frequency system on a chip (RFSoC). Where necessary, the communication signals sent / received via each tile 2200 may be respectively subject to appropriate frequency conversion at a corresponding up / downconverter 2174 (2174-11 to 2174-33), for example with synchronisation control provided by a corresponding PLL (2176-10, 2176-20, and 2176-30). Nevertheless, it will be appreciated that such frequency conversion may not be necessary (e.g., for frequencies covered by the common transceiver platform 2172 such as the RFSoC). Operation of the common transceiver platforms 2172 is coordinated by appropriate control circuitry 2280 - in this example a field programmable gate array (FPGA). It will be appreciated that, in this example, each tile 2200 may support dual band and / or dual polarisation.

[0157] As the tiles 2200 are clustered together, and there is no need to reduce the space between them provided that grating lobes are avoided appropriately (e.g., by accurate positioning / randomization of the tiles 2200 themselves), each cluster can be thus operated as a source of multiple beams 2270 (2270-11 to 2270-33) with a respective transmitter and / or receiver beam 2270 provided via each tile 2200. It will be appreciated that while three antenna tiles 2200 are shown in each respective cluster there may be any suitable number ‘N’ of tiles 2200 forming a corresponding cluster 2210 to generate N corresponding transmitter beams and / or N corresponding receiver beams.

[0158] Similarly, it will be appreciated that while three clusters 2210 are shown, there may be any suitable number ‘M’ of clusters 2210. For M clusters comprising the same number ‘N’ of antenna tiles 2200 this therefore provides for M x N analog transmitter and / or receiver beams with the possibility of additional enhancement provided by digital beamforming.

[0159] Figure 23 illustrates a specific sparse array configuration 2380 that may be realised using clusters as described with reference to Figures 21 and 22.

[0160] The sparse array configuration 2380, in this example, comprises 19 (M = 19) clusters 2310 with each cluster 2310 comprising 3 (N=3) antenna tiles 2300 (each providing reception and / or transmission). If each tile has an 8 x 8 array of antenna elements, this corresponds to 1216 elements per cluster 2310. For an operating frequency of 24.5- 29.5GHz, this configuration can be achieved with a sparse array diameter of approximately 80cm.

[0161] Applications - Dense Array

[0162] It will be appreciated that the antenna architecture described above may, nevertheless, be applied for providing the configuration of a traditional dense array (e.g., with the spacing between different arrays being no greater than (or at least near to) half the wavelength (A)). For example, a 35 element x 35 element (1225 elements) dual beam (TX / RX) square array provided using the architecture would be approximately 18cm square for an operating frequency of 24.5-29.5GHz.

[0163] Summary

[0164] It can be seen therefore, that the antenna architecture described involves a three- dimensional arrangement of antenna elements and diplexers that supports implementation of a mmWave phased array antenna comprising an X-Y grid of antenna elements arranged at a A / 2 or narrower spacing. The architecture may be used to support FDD and / or or multiband TDD. The architecture may also be used to support dual-polarisation. The use of precision manufacturing techniques for the antenna array structure (e.g., involving 3D printing methods) enables a A / 2 antenna spacing for high frequency (>25GHz) systems, and enables an antenna that supports a wide bandwidth (up to an octave).

[0165] The architecture supports implementations in which each antenna element is respectively supported by separate software defined radios (SDRs). Nevertheless, also supports implementations in which, as a result of the way in which beamforming components (e.g., variable gain and phase shifter components) are incorporated into the three-dimensional structure of antenna elements and diplexers, the entire antenna array is supported by a single SDR. The architecture also supports implementations that provide simultaneous multi-beam transmission and reception from the (potentially mmWave) antenna array(s). The architecture also supports implementation of a sparse antenna system comprising multiple (potentially mmWave) antenna arrays.

[0166] Each antenna array may effectively form a sub-array in which hybrid digital beamforming may be utilised to provide an ability to generate digital sub-beams in different directions, within the pointing direction the sub-array, for example where these subbeams are configured to point the beam in the same direction.

[0167] Essentially each tile / dense sub-array made with the technology described herein can be driven by an individual SDR / RFSoC to allow such multi-beam digital beamforming.

[0168] For example, as introduced above, a first architecture may be built in which every tile / subarray becomes an individual element of a sparse array. In this case each tile may be configured to point a beam in the same direction (e.g., using the same phase corrections for each element). To support this, the SDR / RFSoC signal can be adjusted for each sub-array. Moreover sub-beams may be generated within the beam direction selected for the tiles. Advantageously, because each tile has a selected beam direction the side-lobes of each element of the sparse array are reduced and the overall sparse array will generate relatively low-level of side-lobes (compared to use of omnidirectional elements).

[0169] In a second example architecture introduced above, the tile / sub-array may be tiled up to become part of a bigger dense array. In this case the individual elements of the tiles / sub arrays can be controlled to use appropriate phases as part of the larger array. The signal provided by the SDR / RFSoC sources in this case will still allow generation of sub-beams albeit within a narrower analog beam.

[0170] In the first example architecture the analog beam generated by a tile (e.g., an 8x8 element array) will have a larger beamwidth, while in the second example the analog beam can be formed using the elements of multiple tiles. Accordingly if, for example, a dense array of 4 tiles (4x8x8 elements in total) is provided, the analog beamwidth will be significantly narrower.

[0171] Detailed examples have been described above. As those skilled in the art will appreciate, a number of modifications and alternatives can be made to the above embodiments whilst still benefiting from the inventions embodied therein.

[0172] Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

Claims

Claims1. An antenna assembly for supporting communication in a plurality of frequency bands, the antenna assembly comprising: an antenna array comprising a plurality of antenna elements, each antenna element being respectively configured for reception and / or transmission of radio signals in at least a first frequency band and a second frequency band; transceiver circuitry for respectively controlling a gain and / or phase of signals received at and / or to be transmitted from each antenna element; and a diplexer array configured for transferring, between the antenna array and the transceiver circuitry, signals received at and / or to be transmitted from the antenna array; wherein the diplexer array comprises, for each antenna element, at least one respective diplexer, each diplexer being configured for diplexing signals received at and / or to be transmitted from that antenna element in the first frequency band, and signals received at and / or to be transmitted from that antenna element in the second frequency band; wherein each diplexer is generally elongate has a longitudinal axis that extends through and generally orthogonal to a radiating surface of a corresponding antenna element; and wherein each diplexer has a transverse cross-sectional footprint that supports a spacing between the diplexers in the diplexer array of no greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band.

2. An antenna assembly as claimed in claim 1 , wherein the diplexer array comprises, for each antenna element, a respective diplexer pair, each diplexer pair respectively comprising: a first diplexer for diplexing signals, received at and / or to be transmitted from that antenna element, and having a first type of polarisation; anda second diplexer for diplexing signals, received at and / or to be transmitted from that antenna element, and having a second type of polarisation.

3. An antenna assembly as claimed in claim 2, wherein the first diplexer of each diplexer pair has a first longitudinal cross section in a plane corresponding to the first type of polarisation, and the second diplexer of each diplexer pair has a second longitudinal cross section in a plane corresponding to the second type of polarisation, and wherein the first longitudinal cross section of the first diplexer intersects with the second longitudinal cross section of the second diplexer.

4. An antenna assembly as claimed in any preceding claim, wherein each diplexer has a first filter portion comprising a filter for allowing passage of signals in the first frequency band and a second filter portion for allowing passage of signals in the second frequency band.

5. An antenna assembly as claimed in claim 4, wherein the first filter portion and the second filter portion are generally elongate and extend generally parallel to one another and to the longitudinal axis of the diplexer.

6. An antenna assembly as claimed in claim 4 or 5, wherein adjacent diplexers of the diplexer array are arranged in a manner whereby the first filter portions of the diplexers associated with at least one first two-by-two group of antenna elements are closer to a centre of the at least one first two-by-two group of antenna elements than the second filter portions.

7. An antenna assembly as claimed in any of claims 4 to 6, wherein adjacent diplexers of the diplexer array are arranged in a manner whereby the second filter portions of the diplexers associated with at least one second two-by-two group of antenna elements are closer to a centre of the at least one second two-by-two group than the first filter portions.

8. An antenna assembly as claimed in any of claims 4 to 7, wherein the transceiver circuitry comprises a plurality of connection ports for connecting the diplexers to corresponding transceiver circuitry, the plurality of connection ports respectively comprising, for each diplexer:at least one first connection port for connecting the first filter portion to corresponding circuitry for transmitting and / or receiving in the first frequency band; and at least one second connection port for connecting the second filter portion to corresponding circuitry for transmitting and / or receiving in the first frequency band.

9. An antenna assembly as claimed in claim 8, wherein each first and / or second connection port is generally aligned with the first and / or second filter portion for which it provides connectivity.

10. An antenna assembly as claimed in claim 8 or 9, wherein the transceiver circuitry comprises: at least one first integrated circuit, IC, for transmitting and / or receiving in the first frequency band; and at least one second IC for transmitting and / or receiving in the second frequency band.

11. An antenna assembly as claimed in claim 10, wherein the at least one first IC is positioned to have a centre that is aligned with a position within (e.g., equidistant from) a group of first connection ports for the diplexers of at least one first two-by-two group of antenna elements, and wherein the at least one second IC is positioned to have a centre that is aligned with a position within (e.g., equidistant from) a group of second connection ports for the diplexers of at least one second two-by-two group of antenna elements.

12. An antenna assembly as claimed in claim 7, 10 or 11 , wherein the at least one first IC is generally aligned with a centre of at least one first two-by-two group of antenna elements, and wherein the at least one second IC is generally aligned with a centre of at least one second two-by-two group of antenna elements.

13. An antenna assembly as claimed in claim 11 or 12, wherein the at least one first two-by-two group of antenna elements, and at least one second two-by-two group of antenna elements, have at least one antenna element in common.

14. An antenna assembly as claimed in any of claims 8 to 13, wherein each first and / or second IC is a dual polarization transmitter, receiver, or transceiver IC.

15. An antenna assembly as claimed in any of claims 8 to 14, wherein each first and / or second IC is a four-ports, transmitter, receiver, or transceiver IC.

16. An antenna assembly as claimed in any of claims 8 to 15, wherein each first and / or second IC is a beamforming, transmitter, receiver, or transceiver IC.

17. An antenna assembly as claimed in any of claims 8 to 16, wherein the plurality of connection ports comprise a plurality of first type of polarisation connection ports for connecting at least one diplexer for diplexing signals having a first type of polarisation to corresponding circuitry for transmitting and / or receiving signals having the first type of polarisation, and a plurality of second type of polarisation connection ports for connecting at least one diplexer for diplexing signals having a second type of polarisation to corresponding circuitry for transmitting and / or receiving signals having the second type of polarisation.

18. An antenna assembly as claimed in claim 17, wherein the plurality of first type of polarisation connection ports are arranged in one or more rows in which the connection ports aligned with one another in a plane generally parallel to the radiating surface of the antenna array.

19. An antenna assembly as claimed in claim 17 or 18, wherein the plurality of second type of polarisation connection ports are arranged in one or more columns in which the connection ports aligned with one another in a plane generally parallel to the radiating surface of the antenna array.

20. An antenna assembly as claimed in any preceding claim, wherein each diplexer comprises a ridged waveguide diplexer.

21. An antenna assembly as claimed in any of claims 1 to 19, wherein each diplexer comprises a substrate integrated waveguide, SIW, diplexer.

22. An antenna assembly as claimed in any preceding claim, each antenna element, of at least a subset of the antenna elements, is respectively configured as a broadband antenna element that comprises at least one radiating element configured for reception and / or transmission at any of a range of frequencies including the first frequency band and the second frequency band.

23. An antenna assembly as claimed in any preceding claim, each antenna element, of at least a subset of the antenna elements, is respectively configured as a dual- or multi- band antenna element that comprises a plurality of radiating elements, the plurality of radiating elements comprising at least a first radiating element configured for reception and / or transmission in the first frequency band and a secondradiating element configured for reception and / or transmission in the second frequency band.

24. An antenna assembly as claimed in any preceding claim, wherein at least one frequency band of the first frequency band and second frequency band is at a frequency of at least 10GHz, at least 20GHz, at least 25GHz, or at least 30GHz.

25. An antenna assembly as claimed in any of claims 1 to 24, wherein the diplexers of the diplexer array are predominantly formed of a polymeric material.

26. An antenna assembly as claimed in any preceding claim, wherein the diplexers of the diplexer array are predominantly formed of a ceramic.

27. An antenna assembly as claimed in any preceding claim, wherein the diplexers of the diplexer array are manufactured using a 3D printing technology that provides a precision sufficient to support a spacing between the diplexers in the diplexer array of no greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band.

28. An antenna assembly as claimed in any of claims 1 to 25, wherein the diplexers of the diplexer array are manufactured using an injection moulding technology that provides a precision sufficient to support a spacing between the diplexers in the diplexer array of no greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band.

29. An antenna assembly as claimed in any preceding claim, wherein the transceiver circuitry is configured to support time division duplex (TDD) communication and / or frequency division duplex (FDD) communication via the antenna array.

30. An antenna assembly as claimed in any preceding claim, wherein a spacing between adjacent antenna elements of the antenna array is configured to be no greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band.

31. An antenna system comprising at least one antenna assembly as claimed in any preceding claim and at least one software defined radio (SDR) or at least one radio frequency system on a chip (RFSoC) configured for controlling communication via the at least one antenna.

32. An antenna system as claimed in claim 31 , comprising a separate SDR, or a separate RFSoC, for respectively controlling communication via: each antenna element of each antenna assembly; or each of a plurality of different subsets of two or more antenna assembly elements of each antenna.

33. An antenna system as claimed in claim 31, comprising a respective software SDR, or a respective RFSoC, for respectively controlling communication via each antenna assembly of the antenna system.

34. An antenna system as claimed in claim 31 , comprising a plurality of the antenna assemblies, wherein the or each SDR, or the or each RFSoC, is respectively configured for controlling communication via at least two antenna assemblies of the antenna system.

35. An antenna system as claimed in any of claims 31 to 34, comprising a plurality of the antenna assemblies, wherein the plurality of the antenna assemblies are arranged to form a sparse array antenna in which a separation between respective antenna arrays of different antenna assemblies is greater than half a wavelength of radio waves of a highest frequency band of the first frequency band or the second frequency band.

36. An antenna system as claimed in any of claims 31 to 34, comprising a plurality of the antenna assemblies, wherein the plurality of the antenna assemblies are arranged to form a dense array antenna.

37. An antenna system as claimed in any of claims 31 to 36 comprising a plurality of the antenna assemblies, wherein each antenna assembly of the plurality of antenna assemblies is configured to provide a different respective receiver and / or transmitter beam.

38. An antenna system as claimed in any of claims 31 to 37 comprising a plurality of the antenna assemblies, wherein each antenna assembly of the plurality of antenna assemblies is configured for providing a respective plurality of sub-beams which together form the different respective receiver and / or transmitter beam.

39. An antenna system as claimed in any of claims 31 to 38 comprising a plurality of the antenna assemblies, wherein at least one antenna assembly of the plurality of antenna assemblies is configured to operate in at least one frequency band that isdifferent to the frequency bands that another antenna assembly of the plurality of antenna assemblies is configured to operate in.

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