HIGH-FREQUENCY MODULE

Description

technical field

[0001] The present invention relates to a radio frequency (RF) module, intended to form the passive part of a direct radiating array (DRA). State of the art

[0002] Antennas are devices used to transmit or receive electromagnetic signals into free space. Simple antennas, such as dipoles, have limited performance in terms of gain and directivity. Parabolic antennas offer higher directivity but are bulky and heavy, making them unsuitable for applications such as satellites, where weight and size must be minimized.

[0003] We also know of DRA antenna arrays that combine several radiating elements (elementary antennas) with phase shifts to improve gain and directivity. The signals received on the different radiating elements, or emitted by these elements, are amplified with varying gains and phase shifts relative to each other to control the shape of the array's receive and transmit lobes.

[0004] At high frequencies, for example at microwave frequencies, the individual radiating elements are each connected to a waveguide that transmits the received signal to the radio frequency electronic modules, or that supplies the radiating element with a radio frequency signal to be transmitted. The signals transmitted or received by each radiating element can also be separated according to their polarization using a polarizer.

[0005] The assembly consisting of the radiating elements (elementary antennas) in a network, the associated waveguides, any filters, and polarizers is referred to in this text as a passive radio frequency module. The waveguides and associated polarizers are referred to as the feed network. The assembly is intended to constitute the passive part of a direct radiation array (DRA).

[0006] Radiating element arrays for high frequencies, particularly microwave frequencies, are difficult to design. It is often desirable to place the individual radiating elements of the array as close together as possible to reduce the amplitude of secondary emission or reception lobes in directions other than the preferred emission or reception direction. However, reducing the spacing between the different radiating elements of the array is incompatible, firstly, with the minimum size required by the polarizers, and secondly, with the size of the amplification and phase-shifting electronic circuits upstream of the polarizers.

[0007] Therefore, the size of the polarizers and electronics most often determines the minimum spacing between the different radiating elements of an array. The resulting large spacing generates undesirable emission and reception side lobes.

[0008] Other radio frequency modules, on the other hand, require greater spacing between the radiating elements, for example to equip them with an emission cone. It is also sometimes desirable to modify the relative arrangement of the radiating elements.

[0009] US2016 / 218436 discloses an integrated multi-beam antenna system for a satellite comprising a support structure having an alignment plate.

[0010] WO2016 / 202394 relates to a waveguide coupling for a radar antenna in the form of a linear scanner.

[0011] US2009 / 153426 discloses a structure and method for an aperture plate intended for use in a phase-controlled antenna array.

[0012] US2003 / 189515 relates to a phased array antenna design that is modular and scalable in terms of beam quantity, coverage area, and sensitivity at the receive and transmit levels. Brief summary of the invention

[0013] One aim of the present invention is therefore to propose a passive radio frequency module, intended to form the passive part of a direct radiation array (DRA), which is free from or minimizes the limitations of known devices.

[0014] These objectives are achieved in particular through the use of a monolithic radio frequency module obtained by additive manufacturing, comprising: a first layer comprising an array of radiating elements, each radiating element having a cross-section enabling it to support at least one wave propagation mode; a second layer forming an array of waveguides; a fourth layer forming an array of ports; the second layer being interposed between the first and fourth layers; each waveguide being intended to transmit a radio frequency signal in one direction or the other between a port of the fourth layer and a radiating element; the surface area of ​​the first layer being different from the surface area of ​​the fourth layer; the waveguides approaching each other between the fourth and first layers or between the first and fourth layers, the radio frequency module including polarizers between the first and second layers.

[0015] Waveguides thus have a dual function; on the one hand, they allow the transmission of signals between the ports of the fourth layer and the radiating elements of the first layer, and on the other hand, they allow the independent selection of the pitch of the radiating elements and the pitch of the ports of the fourth layer.

[0016] In a first embodiment, the waveguides converge towards each other between the fourth and first layers. The surface area of ​​the first layer is then smaller than the surface area of ​​the fourth layer.

[0017] This arrangement thus makes it possible to reduce the spacing between the radiating elements of the first layer, in order to reduce the amplitude of undesirable secondary lobes ("grating lobes").

[0018] For this purpose, the step (p1) between two radiant elements of the first layer is preferably less than λ\2, λ being the wavelength at the maximum operating frequency.

[0019] The convergent arrangement of the waveguides from the fourth layer to the radiating elements also allows for spacing the ports of the fourth layer. The significant spacing between ports allows, for example, the amplification and phase-shifting electronic circuitry feeding each port to be placed in close proximity to each port, reducing constraints on the circuit's dimensions. This significant spacing also allows for the placement of sufficiently large polarizers near each port, if necessary, to achieve effective signal separation based on polarization.

[0020] In another embodiment, the surface area of ​​the first layer is larger than that of the fourth layer. The waveguides are then spaced further apart between the fourth and first layers. This embodiment allows the use of relatively large radiating elements without requiring a large port layer.

[0021] The arrangement of the radiating elements in the first layer can differ from the arrangement of the ports in the fourth layer. For example, the radiating elements in the first layer might be arranged in a rectangular MxN matrix, while the ports in the fourth layer might be arranged in a rectangular KxL matrix, where M is different from K and N is different from L. This different arrangement can also involve different shapes, for example, a rectangular arrangement in one layer and a circle, oval, cross, hollow rectangle, polygon, etc., in the other layer.

[0022] The radio frequency module may include a third layer interposed between the second and fourth layers.

[0023] Elements of the third layer can perform a signal transformation.

[0024] The third layer may also include a network of elements providing cross-sectional matching between the output cross-section of the ports in the fourth layer and the differently shaped cross-section of the waveguides. Such a third layer may be used, in particular, when only the ports or only the waveguides are grooved.

[0025] The third layer, placed between the second and fourth layers, may contain a filter.

[0026] Each radiating element of the first layer can be provided with at least one striation parallel to the direction of signal propagation.

[0027] The radiating elements of the first layer can also be non-striated and consist of open waveguides or square, circular, pyramidal, spline-shaped horns.

[0028] Radial elements can have a square, rectangular, or preferably hexagonal, circular, or oval external cross-section

[0029] The step (p1) between two radiating elements can be variable within the module.

[0030] The radio frequency module may include waveguides having a square, rectangular, round, oval, or hexagonal cross-section, the inner faces of which are provided with at least one groove extending longitudinally along each inner face of the waveguides.

[0031] Each waveguide in the second layer is preferably designed to transmit either only one fundamental mode or one fundamental mode and one degenerate mode.

[0032] The length of the different waveguides of the second layer is advantageously identical.

[0033] The length of the different waveguides of the second layer can also be variable; in this case, waveguides that are isophase at the wavelength considered will preferably be used, i.e. waveguides all producing an identical phase shift.

[0034] In one embodiment, the different waveguides have different lengths and cross-sections to compensate for the phase variation produced by the different lengths. The different waveguides are preferably isophase, meaning that the phase shifts across the different waveguides are identical.

[0035] The channel of different waveguides is preferably non-straight.

[0036] The waveguides of the second layer are preferably curved.

[0037] The curvature of the individual waveguides in the second layer can vary. For example, the waveguides at the periphery can be more curved than the waveguides in the center.

[0038] One end of all the waveguides may be in a foreground, while a second end of all the waveguides may be in a background.

[0039] Additive manufacturing makes it possible to produce waveguides of complex shapes, including curved waveguides converging in a funnel shape between the layer of radiating elements and the layer of polarizers.

[0040] Additive manufacturing refers to any process for manufacturing parts by adding material, according to computer data stored on a computer medium and defining a model of the part. Besides stereolithography and selective laser melting, the term also encompasses other manufacturing methods involving the hardening or coagulation of liquid or powder, including but not limited to methods based on inkjet printing (binder jetting), DED (Direct Energy Deposition), EBFF (Electron beam freeform fabrication), FDM (fused deposition modeling), PFF (plastic freeforming), aerosol deposition, BPM (ballistic particle manufacturing), powder bed fusion, SLS (Selective Laser Sintering), ALM (Additive Layer Manufacturing), polyjet, EBM (electron beam melting), photopolymerization, etc.However, manufacturing by stereolithography or selective laser melting is preferred because it allows for parts with relatively clean surface finishes and low roughness.

[0041] Monolithic module manufacturing reduces costs by eliminating the need for assembly. It also ensures precise relative positioning of the various components.

[0042] The invention also relates to a module comprising the above elements as well as an electronic circuit with amplifiers and / or phase shifters linked to each port. Brief description of the figures

[0043] Examples of implementation of the invention are given in the description illustrated by the accompanying figures, in which: There figure 1 illustrates a schematic, side view of the different layers of a module according to the invention. figure 2illustrates two examples of implementations of the third layer, in which each element of this layer has either one or two inputs to the fourth layer. figure 3A illustrates a perspective view of the second and third layers of an example module according to the invention. figure 3B illustrates a front view of the second and third layers of an example module according to the invention, viewed from the third layer. figure 3C illustrates a front view of the second and third layers of an example module according to the invention, viewed from the side corresponding to the first layer. figure 4 illustrates a perspective view of an example of the first layer of a module according to the invention. figures 5A to 5C illustrate three examples of radiant elements that can be used in the first layer of a module according to the invention. figure 6illustrates a front view of another example of the first layer of a module according to a second embodiment of the invention. figure 7 illustrates a perspective view of a module comprising a set of waveguides converging towards the radiating elements of the first layer according to a third embodiment of the invention. figure 8 illustrates a view from the fourth layer of the module according to the third embodiment of the invention. figure 9 illustrates a side view of the module according to the third embodiment of the invention. Figure 10 illustrates another side view of the module according to the third embodiment of the invention. figure 11 illustrates a perspective view of a module comprising a set of waveguides diverging towards the radiating elements of the first layer, according to a fourth embodiment of the invention. figure 12illustrates a side view of the module according to the fourth embodiment of the invention. Example(s) of an embodiment of the invention

[0044] There figure 1 illustrates a passive radio frequency module 1 according to a first embodiment of the invention, intended to form the passive part of a direct radiation array (DRA).

[0045] The radio frequency module 1 has four layers 3, 4, 5, 6.

[0046] Among these layers, the first layer 3 comprises a two-dimensional array of N radiating elements 30 (antennas) to emit electromagnetic signals into the ether, respectively to receive the received signals.

[0047] The second layer 4 contains a network of 40 waveguides.

[0048] The third layer 5 is optional; it can also be integrated into layer 4. When present, the third layer 5 includes a network of elements 50, for example section adapters.

[0049] The fourth layer 6 comprises a two-dimensional network, for example a rectangular matrix, with N waveguide ports 60. Each port 60 interfaces with an active element of the DRA, such as an amplifier and / or a phase shifter, forming part of a beamforming network. A port thus allows a waveguide to be connected to an electronic circuit, in order to inject a signal into the waveguides or, conversely, to receive electromagnetic signals into the waveguides.

[0050] It is also possible to use 2N ports 60A, 60B, if a linearly or circularly polarized antenna is used.

[0051] According to the invention, instead of integrating the polarizers into the third layer 5, a layer of polarizers is used between the first layer 3 with the radiating elements and the second layer 4 with the waveguides, or the polarizers are integrated into the radiating elements. This solution has the advantage of bringing the polarizers closer to the radiating elements and avoiding the complexity of transmitting a multi-polarity signal in each waveguide.

[0052] This module 1 is intended for use in a multibeam environment. The radiating elements 30 are preferably placed close together so that the pitch p1 between two adjacent radiating elements is smaller than the wavelength at the nominal frequency at which the module 1 is intended to operate. This reduces the amplitude of the secondary transmission and reception lobes.

[0053] THE figures 3A to 3CThe diagrams illustrate different views of an example module according to a first embodiment of the invention, without the third and fourth layers. In this example, the waveguides 40 and the radiating elements 30 have a square cross-section with four symmetrically arranged grooves on their inner sides. The waveguides converge towards the first layer 3.

[0054] THE figures 7 to 10 illustrate other views of an example module similar to that of the figures 3A to 3C , but in which the waveguides 40 and the radiating elements 30 have a rectangular cross-section with two grooves arranged in the middle of the long sides of the inner flanks. The waveguides are also convergent in the direction of the first layer 3.

[0055] In these modes of implementation of figures 3A to 3C And 7 à 10The distance between two adjacent ports 60 of the fourth layer 6 is preferably greater than the wavelength at the nominal frequency at which the module 1 is intended to be used. This arrangement allows the radiating elements 30 to be placed closer together, in order to reduce unwanted sidelobes in reception and transmission, while spacing the ports 60 of the fourth layer 6 further apart, in order to facilitate connection to the active electronic elements for transmitting or receiving a signal in each waveguide.

[0056] The first layer 3 comprising a network of radiating elements 30 thus has a surface, in a plane perpendicular to the direction d of signal propagation, smaller than the fourth layer 6 with the network of ports 60. The step p1 between two corresponding points of two adjacent radiating elements 30 is therefore smaller than the step p2 between two corresponding points of two adjacent ports 60.

[0057] The step p1 between adjacent elements can be the same in both orthogonal directions, or different. Similarly, the step p2 between adjacent elements can be the same in both orthogonal directions, or different.

[0058] THE Figures 11 to 12 illustrate another embodiment of a module according to the invention, in which the waveguides 40 are divergent in the direction of the radiating elements 30. The surface area of ​​the first layer 3 is thus larger than the surface area of ​​the fourth layer 6, and the pitch p1 between radiating elements 30 of the first layer 3 is larger than the pitch p2 between the ports of the fourth layer 6. This arrangement makes it possible to create a module with large radiating elements 30, for example in a horn shape, without increasing the size of the ports 60 and the network of active elements (not shown) connected to these ports.

[0059] THE figures 3A to 3C And 7 à 12The diagram illustrates waveguides 40 that are separated from one another. According to the invention, these waveguides are, however, linked to one another so as to maintain their relative positioning and form a monolithic assembly. The link between the waveguides can be established, for example, by the first layer 3, the third layer 5, and / or the fourth layer 6. It is also possible to create support elements in the form of bridges between different waveguides.

[0060] An example of a 30 radiant element array in layer 3 is illustrated on the figure 4 In this example, the N radiant elements 30 are arranged in a rectangular matrix, here a square matrix. The cross-section of each radiant element 30 is square and has a 300 striation on each internal edge, the arrangement of the striations being symmetrical. Adjacent radiant elements share a common lateral edge, which allows them to be placed even closer together.

[0061] The phase and amplitude of each radiating element in the first layer 3 allow for high isolation between the different beams. Radiating elements smaller than the wavelength reduce the impact of sidelobes in the covered region.

[0062] There figure 6 illustrates another example of a first layer 3 of radiant elements made up of lines of radiant elements 30 with a variable number of radiant elements depending on the lines, the general shape of the layer forming an octagon.

[0063] It is also possible to make first layers 3 with radiant elements 30 out of phase on successive lines, the value of the phase shift being able to be less than the step p1 between two adjacent elements 30 on the same line.

[0064] A first layer 3 of arbitrary polygonal shape, or substantially circular, can also be made.

[0065] The radiant elements 30 can also be arranged in a triangle, rectangle, or rhombus, with aligned or out-of-phase lines.

[0066] In the embodiments illustrated on the Figures 1 And 3 à 6 , the elements 30 are preferably made up of waveguides whose internal cavity is provided with grooves 300, for example two or four grooves 300 distributed at equal angular distances.

[0067] There figure 5A This illustrates an example of a square cross-section radiating element with four striations, known as a "quad-ridge square". figure 5B This illustrates an example of a radiating element with a rectangular cross-section and two striations, known as a "dual-ridge rectangular". figure 5CThis illustrates an example of a circular cross-section radiating element with four grooves, known as a "quad-ridge circular". The design of radiating elements illustrated with such grooves allows for the creation of radiating elements with dimensions smaller than the wavelength of the signal to be transmitted or received.

[0068] Other forms of radiating elements supporting at least one propagation mode can be implemented, including rectangular, circular, or rounded shapes, ribbed or unribbed. The ribs can be 2, 3, or 4 in number.

[0069] Radiant elements 30 can be single-polarized or dual-polarized. The polarization can be linear, inclined, or circular.

[0070] The pitch p1 between two radiant elements 30 of the first layer 3 is preferably less than or equal to λ / 2, λ being the wavelength at the maximum frequency for which the module is intended.

[0071] According to an embodiment not corresponding to the invention, the radiating elements include polarizers not shown, for example at the junction with the second layer 4. In another embodiment not shown and not part of the invention, polarizers are provided immediately after the free air portion into which the emitted signal is radiated. As will be seen later, according to an embodiment not corresponding to the invention, polarizers may also be provided in the third layer 5.

[0072] The second layer 4 comprises N waveguides 40. Each waveguide 40 transmits a signal from a port 60 and / or an element of the third layer 5 to a corresponding radiating element 30 in transmission, and vice versa in reception. The waveguides 40 also perform a conversion between the arrangement of the elements 60 in layers 5 and 6 and the different arrangement of the radiating elements in the first layer 3.

[0073] Waveguides 40 preferably have a cross-section of practically constant shape and size.

[0074] The waveguides 40 are preferably curved so as to form a transition between the surface of the third or fourth layer 5 and the different surface of the first layer 3 of radiating elements. The waveguides thus form a funnel-shaped volume. In embodiments of Figures 1 , 3A to 3C And 7 à 10 The waveguides converge towards the first layer 3. In the embodiment of Figures 11 to 12 , they diverge towards this first layer 3.

[0075] The second layer 4 can not only allow the pitch between adjacent elements to be adapted; in one embodiment, it can also be made so as to effect a transition between the arrangement of the radiant elements 30 of the first layer 3 and a different arrangement of the ports 60 of the fourth layer 6. For example, the second layer 4 can effect a transition between a network of elements or ports arranged in a rectangular matrix and a network of elements or ports arranged according to a different matrix, or in a polygon, or in a circle.

[0076] At least some 40 waveguides are curved, as can be seen for example on the Figures 3A , 7 And 11 In particular, at least some waveguides are curved in two planes perpendicular to each other and parallel to the longitudinal axis d of the module, as can be seen especially on the figures 9 And 10(first embodiment) and 12 (second embodiment). These waveguides 40 are thus curved in an S shape in two planes orthogonal to each other and parallel to the main direction d of signal transmission.

[0077] The connection plane between the waveguides 40 and the radiating elements 30 on one side, and the connection plane between the waveguides 40 and the elements 50 on the other side, are preferably parallel to each other and perpendicular to the main direction d of signal transmission.

[0078] The waveguides 40 at the periphery of the second layer 4 are more curved and longer than those near the center. The waveguides 40 near the center can be straight.

[0079] The dimensions of the internal channel through the waveguides 40 and those of layer 41, as well as their shapes, are determined according to the operating frequency of the module, i.e. the frequency of the electromagnetic signal for which module 1 is manufactured and for which a stable transmission mode and optionally with a minimum of attenuation is obtained.

[0080] As we have seen, the various waveguides 40 in the second layer 4 have different lengths and curvatures, which influence their frequency response curve. These differences can be compensated for by the electronics feeding each port 60 or processing the received signals. Preferably, however, these differences are at least partially compensated by matching the cross-section of the various waveguides 40, which then have different shapes and / or dimensions.

[0081] The length of the different waveguides 40 of the second layer is advantageously identical, which makes it possible to ensure an identical phase shift of the signals passing through the different waveguides, and therefore to maintain their relative offset.

[0082] The lengths of the various waveguides 40 may differ; in this case, waveguides that are isophase at the wavelength considered are preferably used, that is, waveguides that all produce the same phase shift. To this end, in one embodiment, the various waveguides have different lengths and cross-sections so as to compensate for the phase variation produced by the different lengths.

[0083] It is also possible to use waveguides of different lengths, and / or producing different phase shifts, and to exploit or compensate for these phase shifts with the network of active electronic phase-shifting circuits, in order to control the relative phase shift between radiating elements, and for example to control beamforming.

[0084] The second layer 4 can also, depending on the embodiment, include other waveguide elements such as filters, polarization converters or phase adapters.

[0085] Each 40 waveguide can be designed to transmit a single-polarized or dual-polarized signal.

[0086] The third layer 5 is optional and includes elements 50. In one embodiment, the elements 50 allow a transition between the cross-section of the ports 60 of the fourth layer 6 and the cross-section, which may be different, of the waveguides 40 of the second layer 4, generally corresponding to the cross-section of the radiating elements of the first layer 3. The waveguides of the third layer 5 ensure, for example, a transition between the square or rectangular section of the output of the ports 60 and the section of the waveguides 40 and the radiating elements 30 which is provided with grooves 400 respectively 300.

[0087] The elements 50 of the third layer 5 can also, depending on the embodiments, perform a transformation of the signal, for example using other waveguide elements such as filters, polarization converters, phase adapters, etc.

[0088] The cross-sectional area of ​​the third layer 5 is preferably equal to the cross-sectional area of ​​the fourth layer 6.

[0089] There figure 2 illustrates an example of element 50 of the third layer 5. In the embodiment at the top of the figure, this element 50 has an inlet 51 linked to a port 60 and an inlet 53 linked to the inlet 41 of a waveguide 40.

[0090] In the embodiment shown at the bottom of the figure, this element 50 has two inputs 52A, 52B, each connected to a port 60A respectively 60B of the fourth layer, and an input 53 connected to the input 41 of a waveguide 40. In this embodiment not corresponding to the invention, the element 60 preferably has a polarizer to combine respectively separate two polarities on the ports 60A, 60B, from / to a combined signal on the waveguide 40.

[0091] The entire module 1 is manufactured monolithically by additive manufacturing. According to an embodiment not corresponding to the invention, it is also possible to manufacture the entire module 1 in several blocks assembled together, each block comprising the four layers 3, 4, 5, and 6, or at least layers 3, 4, and 6. Manufacturing by subtractive machining or assembly is also possible, according to embodiments not corresponding to the invention.

[0092] In one embodiment, the module is made entirely of metal, for example aluminum, by additive manufacturing.

[0093] In another embodiment, module 1 comprises a core made of polymer, PEEK, metal, or ceramic, and a conductive coating deposited on the faces of this core. The core of module 1 may be made of a polymer material, ceramic, metal, or alloy, for example, aluminum, titanium, or steel.

[0094] The core of module 1 can be produced by stereolithography or by selective laser melting. The core can consist of different parts assembled together, for example glued or welded.

[0095] The metallic layer forming the envelope can comprise a choice of metals from Cu, Au, Ag, Ni, Al, stainless steel, brass or a combination of these metals.

[0096] The inner and outer surfaces of the core are coated with a conductive metallic layer, for example copper, silver, gold, nickel, etc., plated by chemical deposition without electric current. The thickness of this layer is, for example, between 1 and 20 micrometers, or for example between 4 and 10 micrometers.

[0097] The thickness of this conductive coating must be sufficient for the surface to be electrically conductive at the chosen radio frequency. This is typically achieved using a conductive layer whose thickness is greater than the skin depth δ.

[0098] This thickness is preferably substantially constant on all internal surfaces in order to obtain a finished part with precise dimensional tolerances.

[0099] The deposition of conductive metal on the inner and possibly outer surfaces is achieved by immersing the core in a series of successive baths, typically 1 to 15 baths. Each bath involves a fluid with one or more reactants. The deposition does not require applying a current to the core being coated. Consistent mixing and deposition are achieved by agitating the fluid, for example, by pumping the fluid in the transmission channel and / or around module 1, or by vibrating the core and / or the fluid bath, for example, with an ultrasonic vibrator to create ultrasonic waves.

[0100] The metallic conductive sheath can cover all faces of the core continuously. In another embodiment, module 1 comprises side walls with external and internal surfaces, the internal surfaces defining a channel, said conductive sheath covering said internal surface but not the entire external surface.

[0101] Module 1 may include a smoothing layer intended to at least partially smooth out irregularities in the core surface. The conductive sheath is deposited over the smoothing layer.

[0102] Module 1 may include a tack coat (or primer coat) deposited on the core so as to cover it in an uninterrupted manner.

[0103] The tack coat can be made of conductive or non-conductive material. The tack coat improves the adhesion of the conductive layer to the core. Its thickness is preferably less than the core roughness Ra and less than the resolution of the core additive manufacturing process.

[0104] In one embodiment, module 1 comprises successively a non-conductive core produced by additive manufacturing, an adhesion layer, a smoothing layer, and a conductive layer. The adhesion layer and the smoothing layer reduce the surface roughness of the waveguide channel. The adhesion layer improves the bond between the core, whether conductive or non-conductive, and the smoothing and conductive layers.

[0105] The shape of module 1 can be determined by a computer file stored in a computer data medium and allowing control of an additive manufacturing device.

[0106] The module can be linked to an electronic circuit, for example in the form of a printed circuit board mounted behind the 5-layer ports, with amplifiers and / or phase shifters linked to each port.

Claims

1. Monolithic radio frequency module (1) obtained by additive manufacturing, comprising: a first layer (3) comprising an array of radiating elements (30), each radiating element (30) having a cross-section capable of supporting at least one wave propagation mode, a second layer (4) forming an array of waveguides (40); a fourth layer (6) forming an array of ports (60); the second layer (4) being interposed between the first layer (3) and the fourth layer (6); each waveguide (40) being intended to transmit, in one direction or the other, a radio frequency signal between a port (60) of the fourth layer (6) and a radiating element (30) of the first layer; the surface area of the first layer (3) being different from the surface area of the fourth layer (6); the waveguides (40) converging towards one another between the fourth layer (6) and the first layer (3) or between the first layer (3) and the fourth layer (6), the radio frequency module comprising polarizers between the first and the second layer.

2. Radio frequency module according to claim 1, characterized in that the surface area of the first layer (3) is smaller than the surface area of the fourth layer (6) and in that the waveguides (40) converge towards one another between the fourth layer (6) and the first layer (3).

3. Radio frequency module according to claim 2, characterized in that the pitch (p1) between two radiating elements (30) of the first layer (3) is less than λ / 2, λ being the wavelength at the maximum operating frequency.

4. Radio frequency module according to any one of claims 1 to 3, characterized in that each cross-section of the first layer is provided with at least one ridge parallel to the direction (d) of propagation of the signal.

5. Radio frequency module according to claim 1, characterized in that the surface area of the first layer (3) is greater than the surface area of the fourth layer (6) and in that the waveguides (40) diverge from one another between the fourth layer (6) and the first layer (3).

6. Radio frequency module according to any one of claims 1 or 5, characterized in that the radiating elements (30) of the first layer are non-ridged and consist of open waveguides with a square, rectangular, circular, hexagonal or octagonal cross-section, or pyramidal horns, or spline-shaped elements.

7. Radio frequency module according to any one of claims 1 to 6, characterized in that it comprises a third layer (5) interposed between the second layer (4) and the fourth layer (6) and comprising an array of elements (50) performing a cross-section transition between the cross-section at the output of the ports (60, 60A, 60B) of the fourth layer (6) and the differently shaped cross-section of the waveguides (40).

8. Radio frequency module according to any one of claims 1 to 7, characterized in that it comprises a third layer (5) interposed between the second layer (4) and the fourth layer (6) and comprising a filter.

9. Radio frequency module according to any one of claims 1 to 8, characterized in that each waveguide (40) has a transverse cross-section in the shape of a square, rectangle, hexagon, circle or oval, the internal faces of which are provided with at least one ridge (400) extending longitudinally along each internal face of the waveguides.

10. Radio frequency module according to any one of claims 1 to 9, characterized in that the different waveguides are isophase.

11. Radio frequency module according to claim 10, characterized in that the different waveguides have different lengths and different cross-sections so as to at least partially compensate for the differences in frequency response and / or the phase differences caused by the different lengths and / or different curvatures of the waveguides.