ACTIVE ANTENNA, ESPECIALLY FOR SPACE TECHNOLOGY

Description

Technical field of the invention

[0001] The invention relates to the field of active antennas. It applies more particularly, although not limited to, radars and communication systems.

[0002] The invention is preferably intended for application in the space field. Prior art

[0003] Current active antennas are designed to meet several requirements, particularly in terms of compactness and power.

[0004] An active antenna consists of radiating elements connected to active modules for transmitting and / or receiving radiofrequency waves. The need for compactness is particularly linked to radiofrequency specifications that dictate the spacing between two radiating emission openings. Thus, for a LEO satellite (an acronym for "Low Earth Orbit" or low Earth orbit satellite), the need for compactness is generally greater than for a geostationary satellite known as GEO (an acronym for "Geostationary Earth Orbit" or geostationary Earth orbit satellite).

[0005] An existing solution consists of arranging the radiating elements on a shaped, non-planar surface. An example is described in patent application EP 2 654 121 where the shaped surface is a truncated cone surface and the radiating elements are placed on several generatrices.

[0006] Furthermore, given the thermal power dissipated by each of the active radiofrequency wave transmission and / or reception modules, the active antenna must necessarily include a thermal control system, capable of maintaining the active modules at an appropriate temperature.

[0007] Documents FR 2 881 885 and FR 2 751 473 describe examples of active antennas comprising rows of active modules arranged between beams, the beams being crossed by a cooling system allowing the active modules to be cooled. Presentation of the invention

[0008] The present invention aims to remedy the aforementioned drawbacks.

[0009] For this purpose, the present invention provides an active antenna comprising: a passive portion of an antenna array extended at one end by a tray in which openings are arranged, at least one active assembly for emitting RF radiofrequency waves, called an assembly, through said openings, each assembly comprising: o a first row of active modules facing openings in the tray, o a second row of active modules facing openings in the tray and attached to the first row of active modules, o a beam attached to the tray and held tight between the first row of active modules and the second row of active modules, o a heat transfer duct in contact with the first row of active modules and the second row of active modules and projecting on either side of said first and second rows of active modules.

[0010] The beam of an assembly has a beveled profile cooperating with profiles of the first and second rows of active modules of said assembly to press them against the plate. By beveled profile, it is meant that the beam has, in cross-section, a truncated cone shape, with its small base on the plate side. The first row of active modules is fixedly assembled to the beam.

[0011] Each active module comprises at least one solid-state power amplifier, preferably a plurality of solid-state power amplifiers.

[0012] In particular embodiments, the invention further meets the following characteristics, implemented separately or in each of their technically operative combinations.

[0013] In particular embodiments of the invention, the active antenna comprises a plurality of assemblies arranged against each other, the second row of active modules of one assembly being attached to the first row of active modules of an adjoining assembly.

[0014] In particular embodiments of the invention, intermediate strips are arranged between second rows of active modules of one of the sets and first rows of active modules of an adjoining set.

[0015] In particular embodiments of the invention, the number of active modules per row of an assembly increases from one edge of the antenna plate to a center of the plate and then decreases from said center of the plate to an opposite edge. Such an arrangement of active modules thus has an overall pattern close to a circular shape, and preferably symmetrical, which advantageously makes it possible to obtain improved radiofrequency performance.

[0016] In particular embodiments of the invention, to ensure the correct positioning of the active modules of each row of a set when they are placed on the tray, each of said active modules comprises alignment members capable of cooperating with complementary alignment members arranged on the tray.

[0017] In particular embodiments of the invention, to ensure the correct positioning of the beam of an assembly when it is placed on the plate, said beam comprises alignment elements capable of cooperating with complementary alignment elements arranged on the plate.

[0018] An active antenna according to the invention is advantageously compact and allows, thanks to the close openings on the plate, a dense assembly of active modules, therefore of SSPA amplifiers.

[0019] Such an active antenna is capable of withstanding significant vibration loads. It also proposes the installation of a heat pipe in contact with each of the modules allowing effective thermal regulation of the active modules despite their compactness.

[0020] The invention also relates to a method for mounting an active antenna according to at least one of its embodiments, comprising a step of assembling an assembly, called the first assembly, on the plate. Said step comprises: the assembly of the beam of the first set to the plate, the assembly of the first row of active modules of the first set to said beam, the assembly of the heat transfer duct of the first set to said first row of active modules, the assembly of the second row of active modules of the first set to said first row of active modules.

[0021] The four previous steps are carried out consecutively, one after the other.

[0022] In particular embodiments, the invention further meets the following characteristics, implemented separately or in each of their technically operative combinations.

[0023] In particular embodiments of the invention, the method comprises applying a determined pressure to each active module against the plate, then releasing it after assembling each active module to the beam or to an opposing active module.

[0024] In particular embodiments of the invention, the assembly method comprises a step of assembling another assembly, called the second assembly, adjoining the first assembly, said step comprising: the assembly of the beam of the second set to the plate, the assembly of the first row of active modules of the second set to said beam and to the second row of active modules of the first set, the assembly of the heat transfer duct of the second set to said first row of active modules of the second set, the assembly of the second row of active modules of the second set to the first row of active modules of the second set.

[0025] The four previous steps are carried out consecutively, one after the other.

[0026] In particular embodiments of the invention, the assembly method comprises tilting the first row of active modules of the second set when inserting said active modules between the second row of active modules of the first set already in place and the beam.

[0027] Such an assembly method allows a very dense assembly of active modules, despite limited access to each active module.

[0028] In addition, the assembly of the assembly to the plate as proposed allows it to withstand significant vibration loads. An active antenna made in this way can therefore be suitable for application in the space sector. Such a method allows the second assembly to be assembled both to the beam and to the first assembly. Brief description of the figures

[0029] The invention will be better understood by reading the following description, given as a non-limiting example, and made with reference to the following figures: [ Fig. 1 ] illustrates a perspective view of an active antenna according to an exemplary embodiment of the invention; [ Fig. 2 ] illustrates another side view of the active antenna of the Figure 1 ; [ Fig. 3 ] illustrates another top view of the active antenna of the Figure 1 ; [ Fig. 4 ] illustrates an example of the embodiment of a plate belonging to an active portion of the active antenna; [ Fig. 5 ] illustrates an example of the embodiment of an active module belonging to the active portion of the active antenna of the Figure 1 ; [ Fig. 6 ] illustrates another perspective of the active module of the Figure 5 ; [ Fig. 7] illustrates a side view of an assembly of two active modules of an active RF radio frequency wave emission assembly of the active portion of the active antenna of the Figure 1 ; [ Fig. 8 ] illustrates the steps of assembling a first active RF radiofrequency wave emission assembly on a plate of the active antenna; [ Fig. 9 ] illustrates the steps of assembling a second active RF radiofrequency wave emission assembly, following the assembly of the first active RF radiofrequency wave emission assembly.

[0030] In these figures, like reference numerals from one figure to another designate identical or similar elements. Furthermore, for reasons of clarity, the drawings are not to scale unless otherwise indicated. Description of the embodiments

[0031] The present invention relates to an active antenna.

[0032] The invention is described in the particular context of one of its preferred fields of application in which the active antenna is intended to be embarked in a space vehicle, such as a satellite, and intended to transmit and / or receive radiofrequency signals (RF signals), such as radar signals.

[0033] However, the following description is in no way restrictive and the active antenna may have other applications or uses, without departing from the scope of the invention.

[0034] An active antenna 100 according to a preferred embodiment of the invention is illustrated in figures 1 to 9 .

[0035] The active antenna 100 comprises a passive portion 200, an active portion 400 and a plate 300 forming an interface between said passive portion and said active portion. Passive portion 200 :

[0036] The passive portion 200 may conventionally comprise in particular waveguides, polarizers and radiating openings (not shown in the figures).

[0037] The passive portion 200 has one end, called the first end 201, located on the side of the plate 300. The passive portion 200 has another end, called the second end 202. In the example of the figures, the second end 202 is opposite the first end 201.

[0038] The radiating openings are disposed at the second end 202. As illustrated in the figures 1 to 3 , the passive portion 200 comprises a body 203. By extension, the first end 201 of the passive portion 200 corresponds to a first end of the body 203 and the second end 202 of the passive portion 200 corresponds to a second end of the body 203. Plateau 300 :

[0039] The passive portion 200 extends into the plate on which the active portion 400 is arranged, as illustrated in the figures 1 to 3 . The tray 300 is for example fixed to the passive portion 200.

[0040] The plate 300 thus has a face 301 intended to be opposite the active portion 400.

[0041] In the non-limiting example of figures 1 to 3 , the 300 tray has a circular shape.

[0042] Preferably, the plate 300 has a diameter greater than the largest diameter of the body 203. Thus, the plate 300 has a peripheral portion 303, projecting, forming a collar thus forming a rim on which a panel (not shown in the figures) of the space vehicle can rest and be fixed there.

[0043] The 300 tray and the 203 body can be made in a single piece.

[0044] The tray 300 advantageously comprises openings 310, as illustrated in the Figure 4 . Said openings pass through at least the thickness of the plate 300 and open out through the face 301.

[0045] The openings 310 are preferably arranged in at least two parallel rows. Preferably, the openings 310 are arranged in a plurality of parallel rows, with an even number of rows.

[0046] Preferably, the openings 310 arranged on each row of openings are equidistant. The distance between two openings 310, for each of the rows of openings, is preferably substantially identical. Active Portion 400:

[0047] The active portion 400 comprises at least one active assembly for transmitting and / or receiving RF radiofrequency waves. In the remainder of the description, an active assembly for transmitting RF radiofrequency waves will be referred to as an assembly.

[0048] Preferably, the active portion 400 comprises a plurality of assemblies. Each assembly of the active portion 400 comprises the same constituent elements. An exemplary assembly is now described.

[0049] A set includes: Two rows, called first and second rows, of active modules 410, A beam 450, A heat transfer duct 460.

[0050] A set does not have more than two rows of 410 active modules.

[0051] A set necessarily comprises the same number of active modules 410 on both rows. Each active module 410 of the second row is intended to come substantially opposite an active module 410 of the first row. Each row of active modules 410 of a set is advantageously intended to come opposite a row of openings 310 of the plate 300.

[0052] One set may differ from another set by the number of active modules 410.

[0053] The 450 beam and the 460 heat transfer duct are separate elements. Active module:

[0054] Each active module 410 of an assembly comprises at least one solid-state power amplifier. In the remainder of the description, a solid-state power amplifier will be called an SSPA (Solid State Power Amplifier).

[0055] Advantageously, each active module 410 comprises a plurality of SSPA amplifiers.

[0056] In a preferred embodiment, such as that illustrated in the figures, each active module 410 comprises four SSPA amplifiers.

[0057] Each active module 410 is in the form of a box 420, inside which the SSPA amplifiers are arranged.

[0058] The housings 420 of the active modules 410 preferably have an identical shape.

[0059] Each case, as shown in the Figures 5 and 6 , generally has a rectangular parallelepiped geometric shape. Each housing 420 is for example formed of two shells assembled together.

[0060] Each housing 420 comprises a first face 421 and a second face 422, opposite the first face 421, two longitudinal edges 423 and two lateral edges 425, 426.

[0061] Each 420 case features: a length L, between the two lateral edges 425, 426, a width I, between the two longitudinal edges 423, a thickness e, between the first face 421 and the second face 422.

[0062] The active modules 410 of a set, when placed on the tray 300, are positioned so that: the first face 421 of the housing 420 of an active module 410 of a first row is opposite the first face 421 of the housing 420 of an active module 410 of the second row, a lateral edge of the housing 420 of each active module 410, called first lateral edge 425, is opposite the face 301 of the plate 300, two neighboring active modules 410 of the same row are adjoining at the level of a longitudinal edge 423 of each housing.

[0063] Advantageously, as detailed below, these boxes are not fixed to the plate directly by screws inserted perpendicularly into the plate. Indeed, such an arrangement of screws for fixing the modules would result in a significant limitation in terms of compactness. Thus, the boxes are advantageously fixed, in the active antenna according to the invention, by means of screws arranged parallel to the plane of the plate.

[0064] The active modules 410 are thus positioned perpendicularly to the plate 300, assembled laterally to each other on each row.

[0065] Such an arrangement of the active modules 410 on the tray 300 makes it possible to reduce their size on said tray 300, making it possible to increase the number of active modules 410 to be positioned on said tray 300.

[0066] Each active module 410 comprises at least one radio frequency output interface 427, one RF output interface 427 per SSPA amplifier.

[0067] Thus, in a preferred embodiment, when an active module 410 comprises four SSPA amplifiers, said active module 410 comprises four RF output interfaces 427, as illustrated in the Figure 6 .

[0068] The RF output interfaces 427 are arranged at the first side edge 425 of the housing, and are regularly distributed over said first side edge.

[0069] In an exemplary embodiment, the RF output interfaces 427 of the active module 410 are in the form of waveguides.

[0070] The RF output interfaces 427 of an active module 410 are arranged so that, when said active module 410 is in position on the plate 300, each RF output interface 427 is intended to come respectively opposite an opening 310 of a row of openings 310 of the plate 300.

[0071] Each active module 410 further comprises a seal disposed around each RF output interface 427. This seal will be pressurized before the active module is finally fixed to the plate, after which the mounting pressure is removed. A press is for example used to apply a specific nominal pressure to the seal. The invention advantageously makes it possible to precisely adjust the pressure applied to the seals, in the final assembly.

[0072] Thus, in the non-limiting example of the invention where the active module 410 comprises four RF output interfaces 427, said active module 410 comprises four seals.

[0073] Each seal of an active module 410 is arranged around an RF output interface 427 such that, when the active module 410 is in position on the tray 300, said seal is arranged around an opening 310 of a row of openings 310 of the tray 300.

[0074] Each active module 410 comprises at least one radio frequency input interface 428, one RF input interface per SSPA amplifier.

[0075] Thus, in a preferred embodiment, when an active module 410 comprises four SSPA amplifiers, said active module 410 comprises four RF input interfaces 428, as illustrated in the Figures 5 and 6 .

[0076] The RF input interfaces 428 are arranged at a second side edge 426 of the housing 420 and are regularly distributed over said second side edge.

[0077] In an exemplary embodiment, the RF input interfaces 428 are in the form of coaxial outputs.

[0078] Preferably, in order to ensure the correct positioning of the active modules 410 when they are placed on the tray 300, the active modules 410 may comprise alignment members 432, as illustrated in the Figure 6 , intended to cooperate with complementary alignment members 320 arranged on the plate 300, at the level of the face 301, as illustrated in the Figure 4 The alignment members 432 of an active module 410 are preferably arranged at the level of the first lateral edge 425 of the housing 420 of said active module 410.

[0079] In one embodiment, the alignment members 432 of the active modules 410 are alignment pins and the complementary alignment members 432 320 on the plate 300 are receiving pins. Conversely, and without departing from the scope of the invention, the alignment members 432 of the active modules 410 may be receiving pins and the complementary alignment members 320 on the plate 300 are alignment pins.

[0080] Preferably, each active module 410 of an assembly comprises first orifices 433 for receiving fixing elements, called first fixing elements 510. These first fixing elements 510 are intended to assemble two modules facing each other of the same assembly. The first orifices 433 pass through the thickness of the housing 420 of the active module 410.

[0081] Preferably, the first fasteners 510 are reversible fasteners, i.e., they can be installed and removed as needed.

[0082] In a preferred embodiment, the first fastening elements 510 are clamping screws and the first holes 433 of the active module 410 are threaded, forming nuts for the clamping screws.

[0083] In an exemplary embodiment, as illustrated in the Figures 5 and 6 , each active module 410 has four first orifices 433.

[0084] Preferably, each active module 410 of an assembly comprises second orifices 434 for receiving fixing elements, called second fixing elements 520. These second fixing elements 520 are intended to assemble an active module 410 to the beam 450 of said assembly, as will be described later. The second orifices 434 pass through the thickness of the housing 420 of the active module 410, and are arranged on the side of the first lateral edge 425.

[0085] Preferably, the second fastening elements 520 are reversible fastening elements.

[0086] In a preferred embodiment, the second fastening elements 520 are clamping screws and the second holes 434 of the active module 410 are threaded, forming nuts for the clamping screws.

[0087] In an exemplary embodiment, as illustrated in the Figures 5 and 6 , each active module 410 has two second orifices 434. Beam 450 :

[0088] The beam 450 of an assembly is advantageously a longitudinal beam 450, intended to be arranged between two rows of openings 310 of said plate 300 and to be held tight between the first row of active modules 410 and the second row of active modules 410.

[0089] The 450 beam is advantageously intended for: be assembled to the board 300, opposite the face 301 of said board, be assembled to the first row of active modules 410, in order to maintain the active modules 410 of the first row in position with respect to the plate 300 and the passive portion 200.

[0090] Preferably, in order to ensure its correct positioning on the plate 300, the beam 450 may comprise alignment elements (not shown in the figures) intended to cooperate with complementary alignment elements 330 arranged on the plate 300. The complementary alignment elements 330 arranged on the plate 300 are arranged between two rows of openings 310 of said plate 300 intended to receive two rows of active modules 410 of an assembly, as illustrated in the Figure 4 .

[0091] In one embodiment, the alignment elements of the beam 450 are alignment pins and the complementary alignment elements 330 on the plate 300 are receiving pins. Conversely, and without departing from the scope of the invention, the alignment elements of the beam 450 may be receiving pins and the complementary alignment elements 330 on the plate 300 are alignment pins.

[0092] Preferably, the beam 450 comprises first orifices 451 for receiving fixing elements, called third fixing elements 530. These third fixing elements 530 are intended to assemble the beam 450 to the plate 300. The first orifices 451 of the beam 450 are through.

[0093] In parallel, the plate 300 also comprises first orifices 340 for receiving the third fixing elements 530. The first orifices 340 of the plate 300 extend into the thickness of the plate 300, from the face 301 of said plate 300. The first orifices 340 of the plate 300 are preferably not through the thickness of the plate 300. The first orifices 340 of the plate 300 are arranged on the plate 300 such that, when the beam 450 is in position on the plate 300, said first orifices 340 of the plate 300 are opposite the first orifices of the beam 450.

[0094] Preferably, the third fastening elements 530 are reversible fastening elements.

[0095] In a preferred embodiment, the third fastening elements 530 are clamping screws and the first holes 451, 340 of the beam 450 and of the plate 300 are threaded, forming nuts for said clamping screws.

[0096] Preferably, the beam 450 comprises second orifices 452 for receiving the second fixing elements 520. As described previously, the second fixing elements 520 are intended to assemble the beam 450 to an active module 410. The second orifices 452 of the beam 450 are through.

[0097] The second orifices 452 of the beam 450 are arranged in the beam 450 such that, when the beam 450 and an active module 410 of the first row are in position on the plate 300, said second orifices of the beam 450 are opposite the second orifices 434 of said active module.

[0098] In a preferred embodiment, the second fastening elements 520 are clamping screws and the second holes 434 of the active module 410 and the beam 450 are threaded, forming nuts for the clamping screws.

[0099] The 450 beam has a beveled profile. More specifically, the 450 beam has a trapezoidal cross-section, as illustrated in the Figure 7 The trapezoidal section of the beam has in particular a plane of symmetry passing through the middle of the trapezoid.

[0100] An advantage of this trapezoidal profile beam is that by tightening the active modules opposite each other, they are pressed against the plate 300, without requiring tightening by screwing directly into the plate. This achieves sufficient tightening even without having access for screwing directly into the plate.

[0101] The beam 450 is intended to be positioned on the plate 300 such that its small base 453 is arranged facing the plate 300. In other words, when the beam 450 is in position on the plate 300, the beam 450 gradually tapers towards the plate 300.

[0102] The parts, such as the beams, are for example made of aluminum, a material which has sufficient mechanical characteristics, while having a reduced mass. In a preferred embodiment, as illustrated in the Figure 7, each active module 410 may have, over its entire width, a recess 429 for receiving a portion of the beam 450. Said recess has a shape complementary to a portion of the cross-section of the beam 450, preferably half of the cross-section of the beam 450. In the clamped position, a clearance is left between the beam and the active modules 410, on the face of the beam opposite the plate. This provides good contact at the inclined planes of the beam, which guarantees good mechanical strength. Such a recess 429 is made in the housing 420 of the active modules 410, at the level of the first face 421, and extends from the first lateral edge 425. Thus, when two active modules 410 of a set are positioned opposite each other on the plate 300, they substantially surround the beam 450. The first faces of the housings 420 of said active modules are very close together.

[0103] Such an arrangement of the active modules 410 on the tray 300 makes it possible to reduce their size on said tray, making it possible to increase the number of rows of active modules 410 on the tray 300.

[0104] Such an active antenna is compact and advantageously allows, thanks to the close openings on the plate, a dense assembly of active modules, therefore of SSPA amplifiers. In addition, the arrangement of the heat transfer duct between the two rows of active modules allows effective thermal regulation of the active modules despite their compactness. Heat transfer pipe 460

[0105] The assembly further comprises a heat transfer duct 460 intended to evacuate the heat coming from the active modules 410.

[0106] The heat transfer pipe 460 is for example of the capillary heat pipe type.

[0107] The heat transfer conduit 460 comprises, for example, as illustrated Figure 7, at least one elongated tube 461, hollow, and two longitudinal support plates 462, parallel to each other and arranged, opposite the at least one elongated tube 461, in a diagonally opposite manner. Preferably, the capillary heat pipe comprises two parallel elongated tubes 461 arranged between the two longitudinal support plates 462.

[0108] The heat transfer duct 460 is arranged to be advantageously in contact with both all of the active modules 410 of the first row and all of the modules of the second row of the assembly. Thus, in the illustrated example, the heat transfer duct 460 is arranged so that one of the two longitudinal support plates 462 is in contact with all of the active modules 410 of the first row and the other longitudinal support plate 462 is in contact with all of the active modules 410 of the second row.

[0109] The heat transfer duct 460 preferably projects on either side of the first and second rows of active modules 410.

[0110] Preferably, to hold the heat transfer duct 460 in place against the active modules 410 of the two rows and to ensure thermal contact between the heat transfer duct 460 and said active modules, a thermally conductive paste (not shown in the figures) is placed between the heat transfer duct 460 and the active modules 410 of the two rows. The thermally conductive paste advantageously contributes to the passive thermal regulation of the active modules 410. The thermally conductive paste may be self-hardening.

[0111] According to an example of embodiment, the thermally conductive paste is a component of the MAPSIL ® or Sigraflex ® brand.

[0112] In a preferred embodiment, as illustrated in figures 6 And 7, each active module 410 may have, over its entire width, a groove 430 for receiving a portion of the heat transfer conduit 460. Preferably, the groove 430 has a complementary shape, to within a clearance, of a portion of the cross-section of the heat transfer conduit 460, preferably of half of the cross-section of the heat transfer conduit 460. Such a groove 430 is made in the housing 420 of the active modules 410, at the level of the first face 421. Thus, when two active modules 410 of a set are positioned opposite each other on the plate 300, they substantially surround the heat transfer conduit 460. The first faces of the housings 420 of said active modules 410 are thus very close together, or even joined.

[0113] Such an arrangement of the active modules 410 on the tray 300 makes it possible to reduce their size on said tray 300, making it possible to increase the number of rows of active modules 410 on the tray 300.

[0114] In one embodiment, as illustrated in the figures 1 to 3 , the active portion 400 comprises a plurality of assemblies, the assemblies being attached to each other in parallel.

[0115] The tray 300 comprises a plurality of rows of openings 310, the number of rows of openings 310 corresponding at least to the number of rows of the assemblies. Two rows of openings 310 of the tray 300 are spaced apart by a distance d allowing the insertion of two active modules 410 opposite each other, with a clearance close.

[0116] The assemblies are arranged against each other such that the second face 422 of the housings 420 of the active modules 410 of the second row of an assembly is opposite the second face 422 of the housings 420 of the active modules 410 of the first row of active modules 410 of an adjoining assembly.

[0117] Preferably, the active modules 410 of the second row of an assembly and the active modules 410 of the first row of an adjoining assembly are immobilized relative to each other. To enable such immobilization, each active module 410 comprises third orifices 452 for receiving fixing elements, called fourth fixing elements 540. These fourth fixing elements 540 are intended to assemble together two active modules 410 facing each other of two adjoining assemblies. Said third orifices 452 pass through the thickness of the housing 420 of the active module 410.

[0118] Preferably, the fourth fastening elements 540 are reversible fastening elements.

[0119] In a preferred embodiment, the fourth fastening elements 540 are clamping screws and the third holes 452 of the active modules 410 are threaded, forming nuts for said clamping screws.

[0120] In a preferred embodiment, as illustrated in Figure 7 , an intermediate strip 600 can be inserted between the active modules 410 of the second row of a set and the active modules 410 of the first row of an adjoining set.

[0121] The spacer bar 600 is sized to be held by friction between the active modules 410 of the second row of a set and the active modules 410 of the first row of an adjoining set, when said active modules are positioned on the plate 300.

[0122] On an active antenna with a large number of assemblies (double rows), if all the rows were fixed together, the assembly would then become too hyperstatic, the defects would accumulate, making the assembly impossible. However, fixing the assemblies together remains advantageous for better resistance to lateral accelerations. Thus the assemblies, of two rows each, can be fixed for example three by three, four by four or five by five. Thus the assembly has a sufficiently high lateral resonance frequency, without however preventing mechanical assembly.

[0123] For example, since the active modules have identical external dimensions, an intermediate strip is added at the contact areas between them, while the active modules from one set of two rows to the other are not in contact.

[0124] To improve the mechanical strength of assemblies grouped in groups of three, four or five, the spacer bar can be made of rough material such as Ekagrip ® (stainless steel encrusted with micro-diamonds). This increases the coefficient of friction between the assemblies and reduces the forces in the tightening screws.

[0125] In a preferred embodiment, the active portion 400 may comprise at the end of the heat transfer conduits, other heat transfer conduits, called second heat transfer conduits 500. All of the heat transfer conduits 460 and the second heat transfer conduits 500 form a thermal control system. In a preferred configuration, illustrated in the figures 1 to 3 , the active modules 410 of the assemblies are positioned on the plate 300 so as to present an overall pattern close to a circular shape, and preferably symmetrical. Such a pattern advantageously makes it possible to obtain improved radiofrequency performance.

[0126] Thus, the number of active modules per row of a set increases from an edge B1 of the board 300 to the center C2 of the board 300 then decreases from said center of the board 300 to an opposite edge B3, as illustrated in the figures 1 And 3 . In the example of the figures 1 to 3 , the active portion 400 comprises 14 sets, or 28 rows of active patterns. 132 modules are distributed over these 28 rows. Each active module 410 comprises 4 SSPA amplifiers, or a total of 528 SSPA amplifiers.

[0127] A typical density for the tray is for example 5000 to 8000 openings / m 2< .

[0128] The active antenna according to the invention thus advantageously allows the assembly of a high density of SSPA amplifiers.

[0129] Mechanical vibration tests were carried out and found to comply with the modal and quasi-static specifications. The active antenna according to the invention is thus perfectly suited for installation in a space vehicle, and in particular capable of withstanding the vibration loads inherent in the launch phase. Assembly process:

[0130] An example of a method for mounting the constituent elements of the active portion 400 on the plate 300 is now described.

[0131] Due to the large number of active modules and their dense pattern on the board 300, the assembly of the active modules can only be carried out from the side.

[0132] The method is described in the case of the assembly of a first set then of a second set, adjoining the first set, as illustrated in 1 and 2. Each row of the first set and of the second set comprises, in a non-limiting manner, two active modules 410.

[0133] In the example described, each active module 410 comprises a recess 429 and a groove 430.

[0134] Preferably, the passive portion 200 of the active antenna is previously assembled to the plate 300, for example by screwing.

[0135] The first set is assembled to the board 300. The first set is arranged as close as possible to an edge of the board 300.

[0136] In a first step, as illustrated in the Figure 8 a) , the beam 450 of the first set is assembled to the plate 300.

[0137] The beam 450 is positioned on the plate 300 such that its alignment elements cooperate with complementary alignment elements 330 of the plate 300, thus ensuring the correct positioning of the beam 450 on the plate 300. The first holes 451 of the beam 450 thus coincide with first holes 340 of the plate 300.

[0138] Then the beam 450 is fixed to the plate 300 using the first fixing elements 510.

[0139] When the first fixing elements 510 are clamping screws, said clamping screws are screwed into the first threaded holes 451 of the beam 450 then the first threaded holes 340 of the plate 300, thus causing the beam 450 to be immobilized on the plate 300.

[0140] In a second step, as illustrated in the Figures 8 b) and c) , the active modules 410 of the first row are assembled to the beam 450.

[0141] In a first sub-step, a first active module 410 is positioned on the tray 300 such that its alignment members 432 cooperate with complementary alignment members 320 of the tray 300, thus ensuring the correct positioning of the first active module 410 on the tray 300. The RF output interfaces 427 of the first active module 410 thus coincide with openings 310 of a first row of openings of the tray 300. The seals of the first active module 410 surround said openings of the tray 300. The recess 429 of the first active module 410 cooperates with the beam 450.

[0142] In a second sub-step, a second active module 410, adjacent to the first active module 410, is positioned on the plate 300. The second active module 410 is positioned on the plate 300 in such a way that its alignment members 432 cooperate with complementary alignment members 320 of the plate 300. The second active module 410 is found attached to the first active module 410, at one of their longitudinal edges 423. The RF output interfaces 427 of the second active module 410 thus coincide with other openings 310 of the first row of openings of the plate 300. The seals of the second active module 410 surround said openings of the plate 300. The recess 429 of the second active module 410 cooperates with the beam 450.

[0143] In a third sub-step, the active modules 410 are fixed to the beam 450. A nominal pressure is first applied to the first active module 410 to compress the seals of the first active module 410. This nominal pressure is applied from the second lateral edge 426 and in the direction of the plate 300. Preferably, the nominal pressure exerted is of the order of 150 N.

[0144] When the seals of said first active module 410 are put into compression, the first active module 410 is fixed to the beam 450 using the second fixing elements 520.

[0145] When the second fixing elements 520 are clamping screws, each clamping screw passes through the beam 450 then the first active module 410. Each screw is thus screwed first into the second threaded holes 452 of the beam 450 then into the second threaded holes 434 of the first active module 410, thus causing the beam 450 to be immobilized on the plate 300.

[0146] When said second fastening elements 520 are in place, the nominal pressure on the first active module 410 is released. The seals of the first active module 410 are then correctly positioned around the respective openings 310 of the plate 300.

[0147] A nominal pressure is then applied to the second active module 410 to compress the seals of the second active module 410, in a similar manner to that applied to the first active module 410. Then the second active module 410 is fixed to the beam 450 using the second fixing elements 520, as for the first active module 410.

[0148] In the example of the Figure 8.b , two clamping screws allow each active module 410 of the first row to be securely assembled to the beam 450.

[0149] In this example of implementation of this second step, the active modules 410 are positioned one after the other then put under pressure and assembled to the beam 450 one after the other.

[0150] It is also possible to first position, pressurize and securely assemble the first active module 410 to the beam 450 and then to position, pressurize and securely assemble the second active module 410 to the beam 450.

[0151] It is also possible to first position all the active modules 410 then put them under pressure simultaneously and assemble them securely to the beam 450.

[0152] At the end of this second step, all the active modules 410 of the first row are fixed to the beam 450.

[0153] In a third step, as illustrated in the Figure 8 d) , the heat transfer duct 460 is assembled to the active modules 410 of the first row.

[0154] The heat-conducting paste is deposited on a portion of the heat-transfer duct 460. In the example of the heat-transfer duct 460 formed by at least one elongated tube 461 and two longitudinal support plates 462, the heat-conducting paste is deposited on each of the longitudinal support plates 462. Then the heat-transfer duct 460 is positioned against the active modules 410 of the first row. The heat-transfer duct 460 is placed so that one of the longitudinal support plates 462 on which the heat-conducting paste is deposited is placed against the first face 421 of the housings 420 of the active modules 410 of the first row, with the paste between the longitudinal support plate 462 and the first face 421 of the housings 420 of the modules of the first row. The heat transfer conduit 460 is inserted in particular into the groove 430 provided in the first face 421 of the housings 420 of the active modules 410.This step should be done while the dough is still in its final stages of hardening.

[0155] When the paste begins to harden, it forms a layer of paste which adheres both to the longitudinal support plate 462 of the heat transfer duct 460 and to the active modules 410 of the first row so that the heat transfer duct 460 and the modules are secured together.

[0156] The layer of paste advantageously compensates for the differences in thickness between the first face 421 of the housings 420 of the active modules 410 and the longitudinal support plate 462. Thus, it is possible to ensure that the heat-conducting paste fills any gaps between the longitudinal support plate 462 of the heat transfer duct 460 and the active modules 410 of the first row.

[0157] In a fourth step, as illustrated in the Figures 8 d) and e), the active modules 410 of the second row of the first set are assembled to the active modules 410 of the first row. The beveled profile of the active module on the one hand and of the beam on the other hand allows, by tilting the active module of the second row of the first set, to insert it between the active module of the first row already in place and the beam.

[0158] In a first sub-step, a first active module 410 of the second row is positioned on the plate 300 such that its alignment members 432 cooperate with complementary alignment members 320 of the plate 300, thus ensuring the correct positioning of the first active module 410 on the plate 300. The first active module 410 of the second row is positioned such that the first face 421 of its housing 420 is opposite the first face 421 of the housing 420 of the first module of the first row. The RF output interfaces 427 of the first active module 410 of the second row thus coincide with openings 310 of a second row of openings of the tray 300. The seals of the first active module 410 of the second row surround said openings of the tray 300. The recess 429 of the housing 420 of the first active module 410 of the second row cooperates with the beam 450.The groove 430 of the housing 420 of the first active module 410 of the second row cooperates with the heat transfer duct 460, with the heat-conducting paste between the other longitudinal support plate 462 of the heat transfer duct 460 and said groove 430.

[0159] In a second sub-step, the first active module 410 of the second row is attached to the first active module 410 of the first row.

[0160] A nominal pressure is first applied to the first active module 410 of the second row to compress the seals of said first active module 410. This nominal pressure is applied from the second lateral edge 426 and in the direction of the plate 300. Preferably, the nominal pressure exerted is of the order of 150 N.

[0161] When the seals of said first active module 410 of the second row are put into compression, said first active module 410 of the second row is fixed to the first active module 410 of the first row by means of the first fixing elements 510.

[0162] When the first fixing elements 510 are clamping screws, said clamping screws are screwed first into the first threaded holes 433 of the first active module 410 of the second row and then into the first threaded holes 433 of the first active module 410 of the first row, thus causing the first active module 410 of the second row to be immobilized with the first active module 410 of the first row.

[0163] When said first fixing elements 510 are in place, the nominal pressure on the first active module 410 of the second row is released. The seals of the first active module 410 are then correctly positioned around the respective openings 310 of the tray 300.

[0164] In the example of the Figure 8 d) , four clamping screws allow the first active module 410 of the second row to be fixedly assembled to the first active module 410 of the first row, two clamping screws on either side of the heat transfer duct 460.

[0165] In a third sub-step, a second active module 410 of the second row, adjacent to the first active module 410, is positioned on the plate 300. Said second active module 410 is positioned on the plate 300 in such a way that its alignment members 432 cooperate with complementary alignment members 320 of the plate 300. The second active module 410 is found attached to the first active module 410, at one of their longitudinal edges 423. The second active module 410 of the second row is then positioned in such a way that the first face 421 of its housing 420 is opposite the first face 421 of the housing 420 of the second module of the first row. The RF output interfaces 427 of the second active module 410 thus coincide with other openings 310 of the second row of openings of the tray 300. The seals of the second active module 410 of the second row surround said openings of the tray 300.The recess 429 of the second active module 410 cooperates with the beam 450. The groove 430 of the housing 420 of the first active module 410 of the second row cooperates with the heat transfer duct 460, with the heat-conducting paste between the other longitudinal support plate 462 of the heat transfer duct 460 and said groove 430.

[0166] Then the second active module 410 of the second row is attached to the second active module 410 of the first row, similarly to attaching the first active module 410 of the second row to the first active module 410 of the first row (see above, the second sub-step of the fourth step).

[0167] In this example of implementation of this fourth step, the active modules 410 of the second row are positioned, pressurized and assembled one after the other.

[0168] It is also possible to first position all the active modules 410 of the second row and then put them under pressure simultaneously, or one after the other, and assemble them with the active modules opposite, belonging to the first row.

[0169] At the end of this fourth step, the first assembly of the active portion 400 is assembled to the plate 300.

[0170] The beam 450 is fixedly assembled to the plate 300. Each active module 410 of the first row is fixedly assembled to the beam 450. The active modules 410 of the first row are not fixedly assembled to each other. The active modules 410 of the second row are not fixedly assembled to the beam 450 but only to the active modules 410 of the first row located opposite them. The active modules 410 of the second row are not fixedly assembled to each other.

[0171] The second assembly of the active portion 400 can then be assembled to the plate 300. The second assembly is arranged parallel to the first assembly, adjoining it.

[0172] In a fifth step, the beam 450 of the second set is assembled to the plate 300. The beam 450 of the second set is fixed parallel to the beam 450 of the first set.

[0173] The beam 450 of the second set is assembled in a similar manner to the beam 450 of the first set (see first step).

[0174] In a sixth step, as illustrated in the Figures 9 a) to c) , the active modules 410 of the first row of the second set are assembled to the beam 450 of the second set.

[0175] The active modules 410 of the first row of the second set are assembled to the beam 450 of the second set in a manner similar to the assembly of the active modules 410 of the first row of the first set on the beam 450 of the first set (see second step).

[0176] The RF output interfaces 427 of the active modules 410 of the second set thus coincide with openings 310 of a third row of openings of the tray 300.

[0177] When the beam 450 has a trapezoidal cross-section, the first active modules 410 of the first row of the second set are inserted between the active modules 410 of the second row of the first set and the beam 450 of the second set by tilting said first active modules of the first row of the second set to first introduce their first lateral edge 425, then by bringing said active modules of the first row of the second set perpendicular to the plate 300.

[0178] In an optional next step, the intermediate strip can optionally be slid between the second row of active modules of the first set and the first row of active modules of the second set so as to then fix, between them, for example by the screws 540, the active modules of two successive sets.

[0179] In a seventh step, as illustrated in the figures 9 d), the heat transfer duct 460 of the second set is assembled to the active modules 410 of the first row of the second set. This seventh step is similar to the third step.

[0180] In an eighth step, as illustrated in the Figures 9 d) and e) , the active modules 410 of the second row of the second set are assembled to the active modules 410 of the first row of the first set. This eighth step is similar to the fourth step.

[0181] The RF output interfaces 427 of the active modules 410 of the second set thus coincide with openings 310 of a fourth row of openings of the tray 300.

[0182] At the end of this eighth step, the second assembly of the active portion 400 is assembled to the plate 300. The beam 450 is fixedly assembled to the plate 300. Each active module 410 of the first row is fixedly assembled to the beam 450. The active modules 410 of the first row are not fixedly assembled to each other. The active modules 410 of the second row are not fixedly assembled to the beam 450 but only to the active modules 410 of the first row located opposite them. The active modules 410 of the second row are not fixedly assembled to each other.

[0183] The active modules 410 of the first row of the second set are fixedly assembled with the active modules 410 of the second row of the first set.

[0184] As indicated previously in the optional step carried out before the seventh step, the method may comprise a step of positioning an intermediate strip 600 between the active modules 410 of the second row of the first set and the active modules 410 of the first row of the second set. This step may be carried out after the positioning of the active modules 410 of the first row of the second set but before the fixing of said active modules 410 of the first row of the second set to the active modules 410 of the second row of the first set.

[0185] The intermediate strip 600 is interposed between the active modules 410 of the second row of the first set and the active modules 410 of the first row of the second set and is held by friction between the second faces of the housings 420 of the different active modules 410, connected together by screwing.

[0186] The assembly method described above applies to the assembly of several assemblies, the assemblies being able to comprise different numbers of active modules.

[0187] The above description clearly illustrates that through its various characteristics and their advantages, the present invention achieves the objectives it set for itself. In particular, the invention proposes a compact active antenna, with reduced spacing between the active modules, therefore with a high density of SSPA amplifiers, capable of supporting significant vibration loads and allowing the installation of a heat pipe in contact with each of the modules.

Claims

1. Active antenna (100) comprising: - a passive portion (200) of an antenna array extended at one end (201) by a plate (300) in which apertures (310) are formed, - at least one active assembly for transmitting RF radiofrequency waves, called assembly, through said apertures, each assembly comprising: o a first row of active modules (410) facing apertures (310) of the plate (300), o a second row of active modules (410) facing apertures (310) of the plate (300) and attached to the first row of active modules, o a beam (450) attached to the plate (300) and held clamped between the first row of active modules (410) and the second row of active modules (410), o a heat-transfer duct (460) in contact with the first row of active modules (410) and the second row of active modules (410) and jutting out on either side of said first and second rows of active modules, said active antenna (100) being characterised in that the beam (450) of an assembly has a bevelled profile configured to cooperate with profiles of the first and second rows of active modules of said assembly to press them against the plate (300).

2. Active antenna (100) according to the preceding claim, comprising a plurality of assemblies arranged against one another, wherein the second row of active modules of one assembly is attached to the first row of active modules of an adjoining assembly.

3. Active antenna (100) according to claim 2, wherein intermediate bars (600) are arranged between second rows of active modules of one of the assemblies and first rows of active modules of an adjoining assembly, so as to form groups of several assemblies secured to one another.

4. Active antenna (100) according to claim 2 or 3, wherein the number of active modules (410) per row of one assembly is increasing from one edge (B1) of the plate (300) up to a centre (C2) of the plate and then decreasing from said centre (C2) of the plate towards an opposite edge (B3).

5. Method for mounting an active antenna (100) according to one of the preceding claims, comprising a step of assembling an assembly, called first assembly, on the plate (300), said step comprising: - assembling the beam (450) of the first assembly to the plate (300), - assembling the first row of active modules (410) of the first assembly to said beam (450), - assembling the heat-transfer duct (460) of the first assembly to said first row of active modules (410), - assembling the second row of active modules (410) of the first assembly to said first row of active modules.

6. Method for mounting an active antenna (100) according to claim 5, comprising setting at a determined pressure of each active module against the plate, then relieving after assembly of each active module to the beam or to an opposite active module.

7. Mounting method according to claim 5 or 6, comprising a step of assembling another assembly, called second assembly, adjoining the first assembly, said step comprising: - assembling the beam (450) of the second assembly to the plate, - assembling the first row of active modules (410) of the second assembly to said beam and to the second row of active modules (410) of the first assembly, - assembling the heat-transfer duct (460) of the second assembly to said first row of active modules (410) of the second assembly, - assembling the second row of active modules (410) of the second assembly to the first row of active modules (410) of the second assembly.

8. Mounting method according to claim 7, comprising tilting the first row of active modules (410) of the second assembly upon insertion of said active modules between the second row of active modules (410) of the first assembly already in place and the beam (450).