Low profile dual-band filter using metal insert

Abstract

A dual-band filter (300), which may be incorporated into an array of dual-band filters (1120) for a phased array antenna, may include a first waveguide component (310) having a first waveguide channel (312) and a second waveguide component (320) having a second waveguide channel (322). The waveguide components can be united. An interface between the two waveguide components may define a coupling junction (340) that couples the first waveguide channel (312) to the second waveguide channel (322). The coupling junction (340) may include parallel tunnels (815, 816) perpendicular to the first / second waveguide channels (312, 322). Within each tunnel (815, 816) there may be a filter (332, 334). Each filter (332, 334) may have a set of predetermined transmission characteristics.

Description

Low Profile Dual-Band Filter Using Metal InsertTechnical Field

[0001] The present disclosure relates to a dual band filter that can be used with antennas of a telecommunications network, in particular, though not exclusively as part of a phased array.Background

[0002] For 5G advanced and 6G telecommunications networks, the trend is towards base station radios that can flexibly utilize a large part of the frequency spectrum. Dualband and multi-band filters will play a crucial role in this trend as they select what subbands to use for transmission and reception, and what sub-bands to suppress in order to suppress unwanted emissions and interfering signals. 6G operation within 7-24 GHz (FR3) is particularly challenging considering the many sensitive incumbent services to coexist with, and the resulting sharp pass-band edges that will be required. Filters with air filled metal cavities, and, potentially, ceramic waveguide filters, are among the few candidates to consider for this application.

[0003] The specification requirements, encompassing both electrical and mechanical aspects, for dual-band filters can often be stringent, thus limiting the choice of suitable filter technologies. Most frequently, the primary determinant of filter complexity is the narrow guard band, delimiting a passband and a rejection band. Considering manufacturing tolerances and other parameters affecting filter stability, many filter technologies may be disqualified due to their inability to achieve the required level of stability or steepness (low Q-factor) of the filter function. In such scenarios, the choice of technology is often constrained to air-metal filters (such as cavities, MEMS, etc.).

[0004] Furthermore, dual-band filters should be compatible with phased arrays, imposing size limitations and integration challenges. Typically, the footprint of the filter is required to fit within X / 2 x X / 2 to avoid grating lobes during scanning. However, depending on the antenna requirements and its architecture, the use of subarrays, comprising a few unit cells, is often feasible. Utilizing subarrays offers cost benefits due to the reduced number of TRx units and filters, and is associated with less stringent footprint requirements. Integration challenges arise since antenna elements normallyblock the entire antenna area on the front side, while electronic components and / or connectors cover a large part of the back-side at high frequency. One must therefore find either filter components that are very small and fit between the other electronic components, or small filters that can be sandwiched between the antenna elements and the electronic components, with input and output ports on opposite sides and with interfaces that are suitable for assembly.

[0005] A number of solutions for air-metal dual-band filters have been proposed. A first example was described in Synthesis and Design of Asymmetrical Dual-Bandpass Filters Based on Equivalent Network Simplification”, Philippe Lenoir, Stephane Bila, Fabien Seyfert, Dominique Baillargeat and Serge Verdeyme, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 54, NO. 7, JULY 2006, pp.3090-3097. This example utilized dual-mode cavities. However, utilizing Transverse Electric (TE)113 degenerate modes of circular cavities results in a rather large crosssection. Additionally, this filter requires tuning, incurring extra costs. Owing to its considerable size and expense, such filters are impractical for use in phased arrays.

[0006] An early study was described in Design of Dual-Band Bandpass Filters Based on Metal-Integrated Suspended Line Technology”, Yi Wu and Kaixue Ma, IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS, April 2024. In this study, there was proposed a solution using Metal-Integrated Suspended Line (MISL). This approach leveraged dual mode resonators to design a dual band filter. The filter structure incorporated multiple metal plates, consisting of five plates in a typical instantiation. Such a filter, which is based on quarter-wavelength and three-quarter wavelength dual mode resonators, encounters several challenges: i) how to integrate multiples of such filter into a phased array, ii) the absence of a rigorous design procedure for arbitrary filter functions and therefore, a complex practical implementation of higher order filter functions; iii) it does not allow the two bands to be placed close to each other, rather the ratio between upper and lower pass band is 3.

[0007] A further solution was described in Fahmi, M., Ruiz-Cruz, J. A., Mansour, R.R., and Zaki, K.A. (2010) Compact wide-band ridge waveguide dual-band filter. IEEE International Microwave Symposium (IMS). This solution utilized a dual-band filter with ridge waveguide. It can be applied in scenarios in which there is a significant gap between the lower and upper bands and has the advantage of being smaller. Ridge waveguides suffer two main drawbacks. Firstly, this is more compact if compared tosimilar implementation of this filter with standard waveguides, but still large for potential application in phased array. Secondly, the architecture of the filter imposes placement of both ports at the same side which prevents sandwich integration of the filter within a phased array. For phased arrays a separation of input and output interfaces across opposite sides is required.

[0008] The solutions discussed above have drawbacks that render their application in phased arrays challenging, if not entirely unfeasible.Summary

[0009] A dual-band filter, which may be incorporated into an array of dual-band filters for a phased array antenna, may include a first waveguide component having a first waveguide channel and a second, waveguide component having a second waveguide channel. The waveguide components can be united. An interface between the two waveguide components may define a coupling junction that couples the first waveguide channel to the second waveguide channel. The coupling junction may include parallel tunnels perpendicular to the first / second waveguide channels. Within each tunnel there may be a conductive plate comprising a first and second filter. Each filter may have a set of predetermined transmission characteristics.

[0010] In one aspect, there is provided a dual-band filter. The dual-band filter comprises a first waveguide component comprising a first waveguide channel and a second waveguide component attachable to the first waveguide component and comprising a second waveguide channel. The dual-band filter comprises at least one conductive plate comprising a first filter and a second filter adjacent to the first filter. The first waveguide component and second waveguide component, when assembled, define a coupling junction. The coupling junction comprises a first tunnel and a second tunnel adjacent to the first tunnel. The first tunnel and the second tunnel couple the first waveguide channel to the second waveguide channel. The at least one conductive plate is received between the first waveguide component and the second waveguide component such that the first filter is disposed in the first tunnel and the second filter is disposed in the second tunnel.

[0011] In one embodiment the first tunnel and the second tunnel are perpendicular to the first waveguide channel and the second waveguide channel.

[0012] In one embodiment the at least one conductive plate is parallel to a broad wall of the first waveguide channel and the second waveguide channel.

[0013] In one embodiment the resonators are each u-shaped and the first and last resonators in the filter are asymmetric.

[0014] In one embodiment the first waveguide component and the second waveguide component are identical.

[0015] In one embodiment the first waveguide component and the second waveguide component each comprise half of the coupling junction.

[0016] In one embodiment the at least one conductive plate comprises a single metal plate.

[0017] In one aspect, there is provided a dual-band filter array. The dual-band filter array comprises a first waveguide component comprising a first array of first waveguide channels and a second waveguide component comprising a second array of second waveguide channels. The dual-band filter array comprises at least one conductive plate comprising one or more first filters and one or more second filters. The first waveguide component and second waveguide component, when assembled, define an array of coupling junctions within the assembly. Each coupling junction comprises a first tunnel and a second tunnel adjacent to the first tunnel. Each first tunnel and each second tunnel couple one of the first waveguide channels to one of the second waveguide channels. The at least one conductive plate is received between the first waveguide component and the second waveguide component such that each coupling junction comprises a first filter disposed in the first tunnel and a second filter disposed in the second tunnel.

[0018] In one embodiment the first tunnel and the second tunnel are perpendicular to the first waveguide channel and the second waveguide channel.

[0019] In one embodiment the resonators are each u-shaped and the first and last resonators in the filter are asymmetric.

[0020] In one embodiment the first waveguide component and the second waveguide component are identical.

[0021] In one aspect, there is provided a phased array antenna assembly. The phased array antenna assembly comprises an antenna layer comprising a plurality of antennas and an electronics layer comprising a plurality of transitions, phased array antenna assembly comprises a filter layer comprising at least one dual-band filter arrayfor coupling and filtering signals between the antenna layer and the electronics layer. The at least one dual-band filter array comprises a first waveguide component comprising a first array of first waveguide channels and a second waveguide component comprising a second array of second waveguide channels. The dual-band filter array comprises at least one conductive plate comprising one or more first filters and one or more second filters. The first waveguide component and second waveguide component, when assembled, define an array of coupling junctions within the assembly. Each coupling junction comprises a first tunnel and a second tunnel adjacent to the first tunnel. Each first tunnel and each second tunnel couple one of the first waveguide channels to one of the second waveguide channels. The at least one conductive plate is received between the first waveguide component and the second waveguide component such that each coupling junction comprises a first filter disposed in the first tunnel and a second filter disposed in the second tunnel.Brief Description of the Drawings

[0022] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

[0023] Fig. 1 schematically depicts the concept of a dual-band filter;

[0024] Fig. 2 depicts dual-band filter transmission function;

[0025] Fig. 3 depicts a dual band filter in accordance with an embodiment of the present disclosure;

[0026] Fig. 4 depicts a first waveguide component;

[0027] Fig. 5 depicts the first waveguide component of Fig. 4 with a filter plate;

[0028] Fig. 6 depicts a single line of u-shaped resonators in a uu pattern;

[0029] Fig. 7 depicts a single line of u-shaped resonators in an alternating un pattern;

[0030] Fig. 8 depicts a longitudinal cut cross-section of the dual-band filter of Fig. 3

[0031] Fig. 9 depicts a transversal cut cross-section of the dual-band filter of Fig. 3;

[0032] Fig. 10 depicts the assembled dual-band filter with a portion of the upper waveguide removed to expose the tunnels;

[0033] Fig. 11 depicts the concept of a phased array antenna assembly;

[0034] Fig. 12 depicts a dual-band filter array;

[0035] Fig. 13 depicts a first waveguide component of a dual-band filter array;

[0036] Fig. 14 depicts a first / last asymmetric resonator;

[0037] Fig. 15 depicts a Q-factor curve for the asymmetric resonator;

[0038] Fig. 16 depicts a first alternative asymmetric resonator; and

[0039] Fig. 17 depicts a second alternative asymmetric resonator.Detailed Description

[0040] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0041] There will be described herein embodiments of a compact dual-band filter using a conductive insert and coupling junction with waveguide interfaces. The dualband filter to be described may itself form a unit cell that is replicated across an array of dual-band filters. The primary advantage of the proposed embodiments lies in its compact size, relatively low cost, and its strong potential for integration with phased arrays.

[0042] A dual band filter 100 to be described herein utilizes two single-band filters connected in parallel, as depicted schematically in Fig. 1. Each of two filters fl 102 and f2 104 is designed to have a specified and predetermined transmission function within its allocated band. Both filters interact and therefore their filter functions are not identical to those of isolated single band filters. Fig. 2 shows the transmission bands 202, 204 of each of the filters fl, f2 as a function of frequency. From Fig. 2, it is clear that since two passbands do not overlap, the signal passing though the network in Fig.1 favors a branch / path with better transmission. When operating within the low band, a signal is passing through filter 102 centered at fl while being blocked by filter 104 centered at f2 due to its high rejection at fl, and vice versa.

[0043] In accordance with an embodiment of the present disclosure, a dual-band filter may be implemented using three parts: two waveguide components that together establish a filter case and a conductive insert clamped in between them. The conductive insert typically has a thickness of 50-1000 micrometers (deviation from this range ispossible if required for reasons such as mechanical stability or Q-factor). Certain portions of the conductive insert are removed, thereby creating a frequency-selective resonance structure as will be described in more detail below. If the design specification has sufficient symmetry, particularly in the tunnel designs as will be described in more detail below, then the two waveguide components may be identical, and unite together to define the filter assembly. This simplifies the manufacture and reduces cost.

[0044] A dual band filter in accordance with an embodiment of the present disclosure is shown generally 300 in Fig. 3 in assembled form. The dual band filter 300 includes a first wave guide component 310 and a second wave guide component 320 and a conductive insert 330 (not visible in Fig. 3) comprising a filter arrangement between them. An inlet / outlet waveguide channel 322 of the second waveguide component 320 is visible in Fig. 3. The inlet / outlet channel 322 (and a corresponding inlet / outlet channel of the first waveguide component 310) has a width W and a height H. The specific dimensions of W and H will depend on the frequency band for which the dual band filter is designed. By way of example, a Ku band filter may use a waveguide with inlet and outlet channels having dimensions W=15.8 H=7.9mm (standard R140 WG). The outlet channel 322 is not centered within the surface of the waveguide component 320 but is located adjacent to a second edge 323 of the second waveguide component 320.

[0045] The first wave guide component 310 is shown in isolation in Fig. 4. The first waveguide component 310 includes an inlet / outlet waveguide channel 312 in an outer surface of the component 310. Similar to the inlet / outlet channel 322, the inlet / outlet channel 312 is offset from the center of the surface of the first waveguide component, being located adjacent a first edge 313 of the first waveguide component. When the waveguide is fully assembled, the first edge 313 and second edge 323 are opposite.

[0046] An inner surface 314 of the first waveguide component 310 is the face that unites with the corresponding face of the second waveguide component 320. This face defines a first portion 340 of a coupling junction. Specifically, the coupling junction portion 340 includes a first channel 315 and a second channel 316 that is parallel to the first channel. The first channel 315 and second channel 316 extend perpendicular to the waveguide inlet / outlet channel 312. The first channel 315 and second channel 316 are separated by a separation ridge 317. The first channel 315 and second channel 316 are joined by a lateral channel 318.

[0047] Each of the first channel 315 and second channel 316 has a width wl, w2 respectively. It is desirable to keep the width of both channels wl and w2 as small as possible to reduce input-output signal leakage but larger than Lambda / 4 at the center frequency of the respective channel. For the filter example mentioned above with R140 interface and lower and upper channels of 13GHz and 14.2GHz respectively, the width of the lower channel may be wl=6.25mm while for the upper channel the width may be w2=5.75mm.

[0048] Around the rim of the coupling junction 340, there is a recess 311 that allows a conductive plate 330 to be received into the coupling junction portion of the waveguide component 310 as is shown in Fig. 5. In alternative embodiments, the recess may be omitted, thereby reducing one or more machining steps.

[0049] The second waveguide component 320 may be identical to the first waveguide component. When the first waveguide component 310 abuts the second waveguide component 310, the internal abutting surfaces, each defining a coupling junction portion 340, act together to create the coupling junction. The coupling junction will comprise first and second tunnels formed by the first and second channels 315, 316 respectively of each of the first waveguide component 310 and the second waveguide component 320. The tunnels extend perpendicular to, and interconnect, the inlet / outlet waveguide channel 312 and the inlet / outlet waveguide channel 322. The plate 330, set within the recess 311, will be located between the first waveguide component 310 and the second waveguide component.

[0050] The waveguide components 310, 320 may be produced by milling or by die casting optionally with post-milling if required. The waveguide components 310, 320 may be formed from aluminum, zinc, etc. as is known in the art. Molding in plastic with subsequent metallization is also an option. In one embodiment, the waveguide components may be 3D printed. The waveguide components 310, 320 may be assembled together using screws, rivets, soldering or other suitable joining means. Guide pins (not shown) may be used to orient and align the waveguide components and the plate 330.

[0051] Fig. 5 shows a conductive filter plate 330 located within the first waveguide component 310. The metal plate includes a first slot-line resonator array 332 that corresponds to a first band and an adjacent second slot-line resonator array 334 that corresponds to a second band. When the plate 330 is installed, the first resonator array332 is disposed in the first channel 315 and the second resonator array 334 is disposed in the second channel 316.

[0052] Fig. 6 shows the concept of a single slot-line resonator array 600. The conductive insert typically has a thickness of 50-1000 micrometers and may be made of a metal such as copper or any other suitable metals or alloys as understood by the person skilled in the art. In one embodiment the conductive insert may be Invar (nickel-iron alloy) which has the advantage of good temperature stability. In one embodiment, metalized plastic or other substrate may be used. Certain portions of the metal insert are removed, thereby creating a frequency-selective resonance structure. Fig. 6 illustrates a metal insert featuring an array of slot-line resonators. Each slot-line resonator adopts a U-shape, e.g. resonator 602, resulting in a highly compact structure. The orientation of the resonators can be adjusted to enhance or weaken coupling as required. In Fig. 6, the resonators have a uuuuu pattern. For example, Fig. 7 shows a slot-line resonator array 700 containing both U-shaped resonators 702 and flipped (n-shaped) resonators 704. In Fig. 7, the resonators have an alternating ununu pattern. The same effect can be achieved by altering the width-to-length ratio of a resonator. Choice of specific arrangement depends on the bandwidth of filters to be designed. Both resonator arrangements in Figs. 6 and 7 are known in the art and the specific form of the resonators are not considered pertinent to the present disclosure. The metal insert featuring adjacent slot-line resonator arrays may be produced with high precision techniques such as laser cutting, directional etching, or electrical discharge machining (EDM), etc.

[0053] A single conductive filter plate 330 is shown in which high band and low band filter arrays area formed adjacent each other. In an alternative embodiment, individual high band and low band filter arrays may be produced and laid side by side. However, the single filter plate arrangement 330 is preferred due to precision and cost of manufacturing considerations.

[0054] Fig. 8 shows a longitudinal cut cross-section of the dual-band filter using metal insert of Fig. 3. Fig. 9 shows a transversal cut cross-section. In Figs. 8 and 9, it can be seen that any signal enters the inlet channel 312, is coupled into the tunnels 815, 816 containing the first and second slot-line resonator arrays 332, 334 of the metal insert 330 and then coupled into the exit channel 322. Arrow 810 indicates a polarization of the E-field of the applied excitation signal. Fig. 9 shows the metal insert330 is loaded into tunnel 1 815 and tunnel 2816. Fig. 10 depicts the dual band filter with a portion of the upper waveguide component 320 removed to illustrate how the tunnels 815, 816 are formed and how they accommodate the conductive plate 330.

[0055] The two rectangular tunnels 815, 816 behave as waveguides below their respective cutoff frequencies (signal is not propagating) and guarantee that there will be no spurious response in transmission due to cavity modes.

[0056] The dual band filter unit of Fig.3 can be relatively easy to manufacture. A particular advantage is that such a filter unit can be integrated with a phased antenna array. An architecture of a passive part of a front-end is shown in Fig.11. A signal is propagated vertically to / from antennas 1110 through a filter layer 1120. Feeding of the filters utilize an arrangement of transitions integrated in a Printed Circuit Board (PCB) 1130. Fig. 12 shows a dual band filter array 1200 comprised of an array of the dual band filter unit cells 300. The array 1200 can be formed by two arrays 1210, 1220 of the waveguide component units 310, 320. In one embodiment, the two arrays 1210, 1220 may be identical which can reduce the cost of manufacture but is not essential for operation. Fig. 13 shows a section A-A from Fig. 12 which shows a first array 1210 of waveguide component unit cells. Individual metal plates 330 are disposed into each coupling junction portion of the waveguide component unit cells. Each waveguide component array 1210, 1220 may be formed by milling or die casting as described above for the individual waveguide component units. Individual metal insert plates 330 common to all the units of the array can be inserted into the array before assembling the upper and lower waveguide component arrays 1210, 1220 together. Forming the filter array in such a manner can have significant cost advantages. In an alternative embodiment, a single metal plate comprising an array of sets of parallel filters may be inserted between the waveguide component arrays 1210, 1220.

[0057] The compact dual band filter array can be realized because the coupling junction perpendicular to the inlet and outlet waveguide channels allows the metal insert to be placed parallel to a surface of an antenna array. Any other orientation of the metal insert would require the use of multiple waveguide pieces which would add expense, size and complexity.

[0058] In one embodiment, the coupling of the signal between the waveguide inlet / outlet channels 312, 322 and the coupling junction 340 may be enhanced by deforming the first and last slot-line resonators of each of the slot line resonator arrays332, 334 of the metal plate 330 to make the resonator asymmetric. In a first embodiment, a shape of the resonator is modified to achieve unequal coupling to the upper and lower legs of the resonator. Fig.14 depicts the first / last resonator 1410 in which one leg 1412 of the resonator is longer than the other 1414 (the other resonators have been omitted from Fig. 14 for clarity). The difference in the length of the legs is represented as deltal 1416. Fig. 15 shows a simulation for external Q-factor for the deformed U-shaped resonator. It can be seen that as the resonator approaches symmetry (delta 1^0), external Q^-^, i.e. zero coupling. As the difference in leg length increases, external Q decreases to practically useful levels.

[0059] There are many other ways to deform a resonator that will enable coupling to a feed waveguide. Two examples are shown in Figs 16 and 17.

[0060] The dual band filter described herein implements a waveguide coupling junction that consists of a common waveguide feed connected to two perpendicularly oriented tunnels which behave as waveguides below cut off. Owing to this, metal insert featuring parallel slot-line resonator arrays loaded in tunnels is oriented parallel to E-filed component of excitation signal. Via proper deformation of the first and last resonators of both filter arrays, splitting / combining of signals from lower and upper band filters to a common waveguide interface can be practically realized in a compact unit requiring a minimum number of components to manufacture, in particular for a dual band filter array.

[0061] The junctions in each end of the parallel filter sections are adapted to combine the signal in the two parallel filter sections into a common signal in the waveguide. The conductive sheet acts as an end-wall in the waveguide that blocks wave propagation behind it, with the outermost resonator of both filter chains exposed to and interfering with the currents in the end wall thereby indirectly creating coupling from the resonator to the waveguide.

[0062] In addition to deforming the first and last resonators for coupling the signal to the inlet and outlet channels, it can be desirable to deform one or more of the slot line resonators within the body of the slot line array to achieve stronger coupling. This helps to avoid narrow electrodes between adjacent resonators.

[0063] Advantages

[0064] Reduced size: The proposed filter solution yields a miniaturization (in comparison to cavity filters) and low-profile practical implementation suitable for integration with phased arrays.

[0065] Low production variations: Since the resonator fields are mainly confined in the narrow gaps of the slots, the frequency precision is mainly determined by the metal insert, while the tunnel has less impact. Proposed design relies only on metal and air as materials and therefore production variations are mainly due to tolerances of metal insert structure that contains resonators. The accuracy is very good (<5um) and allows trim-free filters.

[0066] Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.

[0067] While processes in the figures may show a particular order of operations performed by certain embodiments of the present disclosure, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

[0068] Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

ClaimsWhat is claimed is:

1. A dual-band filter (300) comprising:a first waveguide component (310) comprising a first waveguide channel (312); a second waveguide component (320) attachable to the first waveguide component and comprising a second waveguide channel (322); andat least one conductive plate (330) comprising:a first filter (332); anda second filter (334) adjacent to the first filter;wherein the first waveguide component and second waveguide component, when assembled together, define a coupling junction (340) comprising:a first tunnel (815); anda second tunnel (816) adjacent to the first tunnel;wherein the first tunnel and the second tunnel couple the first waveguide channel to the second waveguide channel; andwherein the at least one conductive plate is received between the first waveguide component and the second waveguide component such that the first filter is disposed in the first tunnel and the second filter is disposed in the second tunnel.

2. The dual-band filter of claim 1 wherein the first tunnel (815) and the second tunnel (816) are perpendicular to the first waveguide channel (312) and the second waveguide channel (322).

3. The dual-band filter of claim 1 or 2 wherein the at least one conductive plate (330) is parallel to a broad wall of the first waveguide channel (312) and the second waveguide channel (322).

4. The dual-band filter of any preceding claim wherein a width of each of the first tunnel (815) and the second tunnel (816) is small enough to suppress guided wave propagation inside the respective tunnel.

5. The dual-band filter of any preceding claim wherein the first filter (332) and the second filter (334) each comprise an array of slot-line resonators (600).

6. The dual-band filter of claim 5 wherein the slot-line resonators are u-shaped(602).

7. The dual-band filter of claim 6 wherein the array of slot-line resonators of at least one of the first filter and the second filter comprises an array (600) of u shaped resonators 602 in a uu pattern.

8. The dual-band filter of claim 6 wherein the array of slot-line resonators of at least one of the first filter and the second filter comprises an array (700) of u shaped resonators (702, 704) in an alternating un pattern .

9. The dual-band filter of any one of claims 5 to 8 wherein at least one of a first slot-line resonator and a last slot-line resonator in each of the first filter and the second filter is asymmetric.

10. The dual-band filter of any preceding claim wherein the first waveguide component and the second waveguide component are identical.

11. The dual-band filter of claim 10 wherein the first waveguide component (310) and the second waveguide component (320) each comprise half of the coupling junction (340).

12. The dual-band filter of any preceding claim wherein the first filter (332) and the second filter (334) are each configured to have predetermined transmission characteristics.

13. The dual-band filter of any preceding claim wherein the at least one conductive plate (330) comprises a single metal plate.

14. A dual-band filter array (1120) comprising:a first waveguide component (1210) comprising a first array of first waveguide channels (312);a second waveguide component (1210) comprising a second array of second waveguide channels (322); andat least one conductive plate (330) comprising:one or more first filters (332); andone or more second filters (334);wherein the first waveguide component and second waveguide component, when assembled, define an array of coupling junctions (340) within the assembly, each coupling junction comprising:a first tunnel (815); anda second tunnel (816) adjacent to the first tunnel;wherein each first tunnel and each second tunnel couple one of the first waveguide channels to one of the second waveguide channels; andwherein the at least one conductive plate is received between the first waveguide component and the second waveguide component such that each coupling junction comprises a first filter disposed in the first tunnel and a second filter disposed in the second tunnel.

15. The dual-band filter array of claim 14 wherein for each coupling junction (340) the first tunnel (815) and the second tunnel (816) are perpendicular to the first waveguide channel (312) and the second waveguide channel (322).

16. The dual-band filter array of claim 14 or 15 wherein for each coupling junction (340) the at least one conductive plate (330) is parallel to a broad wall of the first waveguide channel (312) and the second waveguide channel (322).

17. The dual-band filter array of any one of claims 14 to 16 wherein for each coupling junction (340) a width of each of the first tunnel (815) and the second tunnel (816) is small enough to suppress guided wave propagation inside the respective tunnel.

18. The dual-band filter array of any one of claims 14 to 17 wherein the first filter (332) and the second filter (334) each comprise an array (600) of slot-line resonators (602).

19. The dual-band filter array of claim 18 wherein the slot-line resonators are u- shaped.

20. The dual-band filter array of claim 19 wherein the array (600) of slot-line resonators of at least one of the first filter and the second filter comprises an array (600) of u shaped filters in a consecutive uu pattern (602).

21. The dual-band filter array of claim 19 wherein the array of slot-line resonators of at least one of the first filter and the second filter comprises an array (700) of u shaped filters in an alternating un pattern (702, 704).

22. The dual-band filter array of any one of claims 18 to 21 wherein at least one of a first slot-line resonator (1410) and a last slot-line resonator (1410) in each of the first filter and the second filter is asymmetric.

23. The dual-band filter array of any one of claims 14 to 22 wherein the first waveguide component (310) and the second waveguide component (320) are identical.

24. The dual-band filter array of claim 23 wherein for each coupling junction (340) the first waveguide component (310) and the second waveguide component (320) each comprise half of the coupling junction.

25. The dual-band filter array of any one of claims 14 to 24 wherein the first filter (332) and the second filter (334) are each configured to have predetermined transmission characteristics.

26. The dual-band filter array of any one of claims 14 to 25 wherein the at least one conductive plate (330) comprises a single metal plate for each coupling junction, each single metal plate comprising a first filter and a second filter.

27. The dual-band filter array of any one of claims 14 to 25 wherein the at least one conductive plate comprises a single metal plate comprising an array of sets of a first filter and a second filter.

28. A phased array antenna assembly comprising:an antenna layer (1110) comprising a plurality of antennas;an electronics layer (1130) comprising a plurality of transitions; anda filter layer (1120) comprising at least one dual-band filter array for coupling and filtering signals between the antenna layer and the electronics layer, the at least one dual-band filter array comprising:a first waveguide component (1210) comprising a first array of first waveguide channels;a second waveguide component (1210) comprising a second array of second waveguide channels; andat least one conductive plate (330) comprising:one or more first filters (332); andone or more second filters (334);wherein the first waveguide component and second waveguide component, when assembled, define an array of coupling junctions (340) within the assembly, each coupling junction comprising:a first tunnel (815); anda second tunnel (816) adjacent to the first tunnel;wherein each first tunnel and each second tunnel couple one of the first waveguide channels to one of the second waveguide channels; andwherein the at least one conductive plate is received between the first waveguide component and the second waveguide component such that each coupling junction comprises a first filter disposed in the first tunnel and a second filter disposed in the second tunnel.

29. The phased array antenna assembly of claim 28 wherein for each coupling junction (340) the first tunnel (815) and the second tunnel (816) are perpendicular to the first waveguide channel and the second waveguide channel.

30. The phased array antenna assembly of claim 14 or 29 wherein for each coupling junction (340) the at least one conductive plate (330) is parallel to a broad wall of the first waveguide channel (312) and the second waveguide channel (322).

31. The phased array antenna assembly of any one of claims 28 to 30 wherein for each coupling junction (340) a width of each of the first tunnel (815) and the second tunnel (816) is small enough to suppress guided wave propagation inside the respective tunnel.

32. The phased array antenna assembly of any one of claims 28 to 31 wherein the first filter (332) and the second filter (334) each comprise an array (600) of slotline resonators.

33. The phased array antenna assembly of claim 32 wherein the slot-line resonators are u-shaped (602).

34. The phased array antenna assembly of claim 33 wherein the array of slot-line resonators of at least one of the first filter and the second filter comprises an array (600) of u shaped filters in a uu pattern (602).

35. The phased array antenna assembly of claim 33 wherein the array of slot-line resonators of at least one of the first filter and the second filter comprises an array (700) of u shaped filters in an alternating un pattern (702, 704).

36. The phased array antenna assembly of any one of claims 32 to 35 wherein at least one of a first slot-line resonator (1410) and a last slot-line resonator (1410) in each of the first filter and the second filter is asymmetric.

37. The phased array antenna assembly of any one of claims 28 to 22 wherein the first waveguide component and the second waveguide component are identical.

38. The phased array antenna assembly of claim 37 wherein for each coupling junction (340) the first waveguide component (310) and the second waveguide component (320) each comprise half of the coupling junction.

39. The phased array antenna assembly of any one of claims 28 to 38 wherein the first filter (332) and the second filter (334) are each configured to have predetermined transmission characteristics.

40. The phased array antenna assembly of any one of claims 28 to 39 wherein the at least one conductive plate (330) comprises a single metal plate for each coupling junction, each single metal plate comprising a first filter (332) and a second filter (334).

41. The phased array antenna assembly of any one of claims 28 to 39 wherein the at least one conductive plate (340) comprises a single metal plate comprising an array of sets of a first filter and a second filter.

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