EP3086409A1 - Structural antenna module including elementary radiating sources with individual orientation, radiating panel, radiating network and multibeam antenna comprising at least one such module - Google Patents

Abstract

Each radiating source of the structural module comprises a radiating horn (16) connected to an RF chain (10) via a bent ring (18), the bent ring being intended to orient the radiating horn (16) in one direction desired. The bend of the bent ring (18) has an opening angle of predefined value for each horn individually according to the desired orientation, and a vertex (27) placed in a plane of symmetry of the RF chain orthogonal to the XY plane containing the RF chain. The RF channels of each radiating source can then be arranged next to each other and be integrated into structural planar subassemblies, reducing the number of parts necessary for the development of the multibeam antenna.

Description

The present invention relates to an antenna structural module incorporating elementary radiating sources with individual orientation, a radiating panel comprising a structural module, a radiating network comprising a plurality of radiating panels and a multibeam antenna comprising at least one structural module. It applies to the space domain such as satellite telecommunications and more particularly to multibeam antennas comprising a network of several radiating sources placed in the focal plane of a reflector.

A radiant source is constituted by a radiating element, for example a horn, connected to a radiofrequency (RF) chain. The RF chain comprises RF components for switching from a guided propagation mode of the electromagnetic waves to a radiated mode and performs for each beam, the transmission and reception functions in a particular frequency band, for example the Ka band. . The transmission and reception functions can be carried out in single-polarization to cover the needs of the users or in bi-polarization to provide links to land anchor stations (in English: gateway).

In multibeam antenna architectures, several independent elementary radiating sources are arrayed together in the focal plane of a reflector. The assembly of the different radiating sources is complex because it often requires maintaining the radiating sources with a specific orientation to limit the phase aberrations related to the defocusing of the horn relative to the center of the reflector and to maximize the performance of the antenna for each beam. Each radiating source is assembled on a mechanical support by an interface specific to each horn. This individual assembly of each source requires to individually manage the interface of each RF chain and the adjustment of the orientation of each horn, which does not allow to pool the production of RF chains because their RF axes are not parallel to each other. The individual management of each source therefore has a significant cost.

To facilitate the individual orientation of each radiating source, as shown in FIG. figure 1 , it is known to individually fix the radiating sources on a structural plate 13 in which are machined distribution waveguides 14 for conveying RF signals between the radiating source and input / output ports of a device. RF signal processing. The distribution waveguides are connected to outputs of the RF channels 10 by flexible waveguides 15 for individual orientation of each radiating source. The structural plate 13 then ensures the routing of the distribution waveguides 14 as well as the support and the orientation of the RF chains relative to the reflector of the multibeam antenna. However, this solution imposes an assembly of the RF chains independently of each other, an individual orientation of each RF chain and associated horn, and requires the use of many flexible waveguide orientation inducing additional ohmic losses and a additional thermal power to dissipate. In addition, this solution is only possible when the sources of the focal network are sufficiently spaced apart from each other to allow the routing of the distribution waveguides between the RF channels supported by the structural plate.

To our knowledge, there is currently no structural antenna module comprising a set of radiating sources whose RF channels are completely integrated in a common support, and allowing the individual orientation of the radiating horns.

A first object of the invention is to overcome the drawbacks of the known radiating source networks, and to realize an antenna structural module in which the RF axes of the RF chains of all the radiating sources are arranged in the same plane and in which the orientation of the radiating horns is ensured without modifying the orientation of the RF chain axes.

A second object of the invention is to provide an antenna structural module comprising a plurality of radiating sources integrated in a one-piece assembly.

For this, the invention relates to an antenna structural module incorporating elementary radiating sources, each radiating source comprising a radiofrequency chain connected to a radiating horn. The RF chain comprises a main waveguide having a longitudinal axis arranged perpendicularly to an XY plane, an OMT orthomode transducer having two transverse branches orthogonal to each other, located parallel to the XY plane and coupled perpendicularly to the main waveguide by slots coupling. The radiating horn is coupled to an end end of the main waveguide via a bent-orientation ring for orienting the radiating horn in a desired direction different from the longitudinal axis of the main waveguide, the elbow of the orientation ring being placed in a plane of symmetry of the RF chain, the plane of symmetry being orthogonal to the XY plane and containing the bisector of the angle formed by the two transverse branches.

Advantageously, the structural module may further comprise a support plate common to all the radiating sources, the RF channels being completely integrated in the support plate.

Advantageously, the orientation ring associated with each radiating horn can be housed in a dedicated opening arranged in a front face of the support plate. Alternatively, the terminal end of the main waveguide of each RF chain may be housed in a dedicated opening formed in a front face of the support plate and the orientation ring associated with each radiating horn may be fixed on one face before the support plate, in the extension of the corresponding terminal end.

Advantageously, the orientation ring of each radiating source may consist of three mutually integral parts, the three parts being constituted by two rigid access waveguides having different longitudinal axes and intended to be respectively connected to a horn radiating and to an RF chain, and a waveguide section localized adaptation between the two access waveguides, the adaptation waveguide section forming the elbow of the orientation ring.

Alternatively, the orientation ring may comprise a coupling iris.

The invention also relates to a radiating panel having a structural module.

Advantageously, the radiating sources may be machined in a matrix in a common support plate and may comprise respective supply and output waveguides, routed in the common support plate and respectively connected to input and output ports. output grouped next to each other on the radiating panel.

The invention also relates to a radiating network comprising at least one radiating panel.

Advantageously, the radiating network may comprise several radiating panels, which can be oriented independently of one another.

The invention also relates to a multibeam antenna comprising at least one radiating network.

• figure 1 : un schéma en coupe d'un exemple de réseau de sources rayonnantes, selon l'art antérieur ;
• figure 2 : un schéma en coupe transversale d'un exemple de module structural d'antenne intégrant des sources rayonnantes élémentaires à orientation individuelle, selon l'invention ;
• figure 3 : un schéma illustrant un exemple de plusieurs chaînes RF montées parallèlement entre elles sur deux étages, selon l'invention ;
• figure 4 : trois schémas illustrant respectivement, selon deux plans différents et selon une vue en transparence, un premier exemple de bague d'orientation coudée, selon l'invention ;
• figure 5 : un schéma illustrant, selon une vue en transparence, un deuxième exemple de bague d'orientation coudée, selon l'invention ;
• figure 6a : un schéma en coupe transversale illustrant la structure interne d'un premier exemple de chaîne RF planaire, selon l'invention ;
• figure 6b : un schéma en coupe transversale illustrant un exemple d'OMT dissymétrique, selon l'invention ;
• figures 7a et 7b : deux vues illustrant la structure interne de l'étage supérieur, respectivement de l'étage inférieur, de deux chaînes RF empilées, selon l'invention ;
• figure 8a : un schéma en vue de dessus, illustrant un exemple de réseau rayonnant sectorisé en plusieurs panneaux rayonnants indépendants, selon l'invention ;
• figure 8b : un schéma illustrant un exemple d'implantation des sources rayonnantes et des accès d'entrée et de sortie sur les panneaux rayonnants de la figure 8a, selon l'invention ;
• figure 8c : un schéma illustrant un exemple de découpe des plaques de support de chaque panneau rayonnant d'un réseau rayonnant sectorisé, selon l'invention ;
• figure 9 : un exemple d'antenne multifaisceaux, selon l'invention.

Other features and advantages of the invention will become clear in the following description given by way of purely illustrative and non-limiting example, with reference to the attached schematic drawings which represent:

• figure 1 : a sectional diagram of an example of a network of radiating sources, according to the prior art;
• figure 2 a cross-sectional diagram of an example of an antenna structural module incorporating elementary radiating sources with individual orientation, according to the invention;
• figure 3 : a diagram illustrating an example of several RF chains mounted parallel to each other on two floors, according to the invention;
• figure 4 three diagrams respectively illustrating, in two different planes and in a view in transparency, a first example of bent orientation ring, according to the invention;
• figure 5 : a diagram illustrating, in a transparency view, a second example of an angle ring, according to the invention;
• figure 6a a cross-sectional diagram illustrating the internal structure of a first example of a planar RF chain, according to the invention;
• figure 6b : a cross-sectional diagram illustrating an example of asymmetric OMT, according to the invention;
• Figures 7a and 7b two views illustrating the internal structure of the upper stage, respectively the lower stage, of two stacked RF chains, according to the invention;
• figure 8a : a diagram in top view, illustrating an example of radiating network sectored into several independent radiating panels, according to the invention;
• figure 8b : a diagram illustrating an example of implantation of the radiating sources and the accesses of entry and exit on the radiant panels of the figure 8a according to the invention;
• figure 8c : a diagram illustrating an example of cutting the support plates of each radiating panel of a sectorized radiating network, according to the invention;
• figure 9 : an example of a multibeam antenna, according to the invention.

The figure 2 illustrates an example of an antenna structural module incorporating elementary radiating sources with individual orientation, according to the invention, and the figure 3 illustrates an example of arrangement of several RF chains in parallel with each other. Each radiating source comprises an RF radio frequency chain 10 comprising a main waveguide 31, visible on the figure 3 , and a radiating horn 16 coupled to the waveguide main 31. According to the invention, each radiating source further comprises a bent orientation ring 18 connected to a terminal end 5 of the main waveguide 31 of the corresponding RF chain 10 and coupled to the radiating horn 16, the ring angled orientation being for orienting the radiating horn in a desired direction, different from the direction of orientation of the main waveguide 31 of the RF chain. Each orientation ring 18 has a bend having an opening angle whose value is individually defined according to the desired individual orientation for the associated radiating horn. The orientation of each horn is performed by the orientation ring 18 by individually adjusting, for each horn, the opening angle of the elbow of the corresponding orientation ring. The RF chains can be respectively mounted in cavities of a support plate 17 common to all the radiating sources or completely integrated into the support plate as shown in FIG. figure 2 . Advantageously, the orientation ring associated with a horn can be fixed on a front face 19 of the support plate 17 or can be housed in a dedicated opening of the front face 19 of the support plate 17. In the case where the ring orientation associated with a horn is fixed on the front face 19 of the support plate 17, the end end 5 of the main waveguide 31 of the corresponding RF chain is housed in a dedicated opening arranged in the front face of the plate support 17 so as to ensure the continuity of the connection between the main waveguide 31 and the orientation ring 18. The angled orientation ring eliminates all the flexible cables and allows to share the assembly of all RF channels in a single common support. The RF chains can then be arranged under the common support or be machined in the common support parallel to each other as shown for example on the figure 3 wherein the common carrier has been omitted and wherein the RF chains 10a, 10b, 10c have two different stages 36, 37 for dual frequency operation.

As shown on the example of figure 4 each angled orientation ring may consist of three mutually integral parts, the three parts being constituted by two access waveguides 21, 22, intended to be respectively connected to a radiating horn and to a RF chain, and an adaptation waveguide section 20 located between the two access waveguides 21, 22 and forming a coupling iris between the two access waveguides. The two access waveguides 21, 22 may for example be circular or square section. The access waveguide 22 may be connected to the radiating horn and the access waveguide 21 may be connected to the main waveguide 31 of the RF chain, the two access waveguides having respective axes oriented in different directions. The two access waveguides 21, 22 and the matching waveguide section 20 form a bent assembly, the bend having an apex 27 located on the adapter waveguide section 20 and a aperture angle Θ whose value is predefined individually for each horn so as to tilt the axis 23 of the access waveguide 22 connected to the horn with respect to the axis 24 of the access waveguide 21 connected to the RF channel in the desired direction. This makes it possible to orient the radiating horn with respect to the support plate 17 and thus to orient the direction of radiation of the horn, this direction of radiation corresponding to the axis 23. The angle of inclination α of the axis 23 relative to the axis 24 is between zero and a few degrees, its value being defined according to the location of the horn on the support plate and therefore according to its location relative to the focal point of the radiating network of an antenna equipped with a reflector. The opening angle Θ of the elbow depends on the position Δ (x, y) of the radiating source in the network and the equivalent focal length Fe of the antenna, according to the following relation: $$\mathrm{\Theta }=\arctan \left(\mathrm{\Delta }\left(\mathrm{x},\mathrm{there}\right)/\mathrm{Fe}\right)$$

Each angled orientation ring therefore makes it possible to orient a radiating horn with respect to the support plate and thus to correctly orient said radiating horn with respect to a reflector of a multibeam antenna. The angled orientation ring can be made by machining the waveguides 21, 22, 20 in the mass in the form of two complementary half-shells which are assembled by any known technique to reconstruct complete waveguides.

Alternatively, as shown on the figure 5 , the angled orientation ring can be made in a single part in a room monobloc for example using a 3D printer. In this case, the bent orientation ring is a piece of flexible strand, for example a cylinder or a hose, which allows to achieve larger taper angles of the horn.

The figure 6a illustrates a cross-sectional diagram of an example of a planar RF chain operating in a single frequency band, according to the invention. The RF chain, produced in waveguide technology, comprises a main waveguide 31 having a longitudinal axis arranged perpendicularly to the XY plane, an orthomode transducer OMT 30, radiofrequency components of couplers 33 and filters 32 operating in bipolarization mode and input / output ports 34, respectively dedicated to the two polarizations. The input / output ports may be in linear or circular polarization. The OMT may be symmetrical and have four transverse branches or alternatively, be asymmetrical and have two transverse branches orthogonal to each other. On the example of the figure 6a , OMT comprises an axial excitation input coupled to the main waveguide 31 and two transverse branches 41, 42, orthogonal to each other, located in the XY plane and coupled perpendicularly to the main waveguide 31 by two slots of FIG. coupling not shown. The two coupling slots are arranged in the wall of the main waveguide 31 and are spaced angularly by an angle θ equal to 90 °. The transverse branches of the OMT are connected to the radiofrequency components 32, 33. The main waveguide 31 has an upper end intended to be connected to a radiating horn 16 via the bent ring 18. The RF components, type of couplers 33 and 32, are dedicated to the processing of RF signals corresponding to the same frequency band. The OMT feeds the horn (in transmission), or is fed by the horn (in reception), selectively with either a first electromagnetic mode having a first linear polarization, or with a second electromagnetic mode having a second linear polarization orthogonal to the first . The first and second polarizations are associated with two electric field components Ex, Ey whose orientation is imposed by the orientation of the RF chains located in the XY plane and thus by the position of the two coupling slots. the orientation of the Ex field is parallel to the waveguide of the transverse branch 42, the orientation of the field Ey is parallel to the waveguide of the transverse branch 41.

The Figures 7a and 7b illustrate two views of an example of two stacked planar RF channels allowing operation in two different frequency bands, according to the invention. For operation in several different frequency bands, for example two frequency bands respectively dedicated to transmission and reception, it is possible to stack several different RF channels, respectively dedicated to each frequency band, in planar layers. different. In this case, the structure of the RF chain of each radiating source therefore comprises at least two different stages, respectively upper 36 and lower 37, stacked one above the other and respectively dedicated to the reception frequency band. and the frequency band of the radiofrequency signals. Each radio frequency stage is arranged perpendicularly to the longitudinal axis of the main waveguide 31 of the RF chain.

On the Figures 7a and 7b , the OMT 30 coupled to the main axial waveguide 31 common to all transmit and receive signals is the same as on the figure 6a and has two transverse branches per floor, but it is not essential, an OMT with four transverse branches can also be used. The upper transverse branches 41, 42 connected to the radiofrequency components of the upper RF stage 36, can be dedicated to the reception of the RF signals and the two lower transverse branches 43, 44 connected to the radiofrequency components of the lower RF stage 37, can be dedicated to the emission of RF signals. The axial main waveguide 31 is machined in the thickness of the two planar layers constituting the upper and lower stages, and is coupled on the one hand to the upper transverse branches 41, 42 of the OMT by first axial coupling slots. and secondly to the lower transverse branches 43, 44 of the OMT by second axial coupling slots. The first axial coupling slots are located at the same first height in the wall of the axial waveguide and angularly spaced at an angle equal to 90 ° and respectively, the second axial coupling slots are located at the same second height in the wall of the axial waveguide and angularly spaced at an angle equal to 90 °. The first height corresponds to the upper stage of the RF chain and the second height corresponds to the lower stage of the RF chain. To reduce the size of the RF chain, the first axial slots may be aligned above the second axial slots, but this is not essential, they can also be angularly offset relative to each other.

Advantageously, in the case where operation in several frequency bands is desired, it is sufficient to increase the number of stages of the RF chain, each stage being dedicated to one of the desired frequency bands.

Each RF chain may for example be manufactured in two complementary parts, called half-shells, by a known machining process, the two metal half-shells are then assembled together by any type of known connection, welding, glue, screw. The radiofrequency components are then constituted by grooves machined in the two metal half-shells.

In the case of an application in the field of telecommunications, the dissymmetry of the angled orientation ring has no impact on the performance of the radiating sources because the main input excitation waveguide to which is connected the radiating horn is sized to let propagate only one mode of propagation corresponding to the fundamental mode. Consequently, all the other modes, and in particular the odd-symmetrical modes generated by the dissymmetry of the bent orientation ring, can potentially be eliminated by traps placed at the input of the excitation assembly.

In order not to affect the radiation characteristics of the radiating source thus produced, the elbow of the orientation ring 18 must be placed in a plane of symmetry of the RF chain, with respect to the main field components Ex, Ey. generated in the axial main waveguide 31 by the OMT. In fact, in the absence of respect of the plane of symmetry, the bend will be seen as a different defect by the two transverse branches of the RF chain and by the two coupling slots angularly spaced by 90 °, which will have the consequence of deteriorate the purity of the polarization. The fitting of the orientation ring 18 with respect to the RF chain must therefore be realized taking into account the orientation of the two orthogonal main fields Ex, Ey generated in the main axial waveguide 31 of the RF chain. Relative to the two orthogonal main fields Ex, Ey, the plane of symmetry is the plane containing the bisector of the angle formed by the orientation directions of the two main fields Ex and Ey. The elbow must therefore be positioned in this plane of symmetry so as to be seen with the same phase by the two coupling slots of the planar RF chain and so that the radiofrequency discontinuity generated by the elbow causes the same impact on the two components of the fundamental mode field. On the diagram of the figure 6a the only plane of symmetry possible is the plane perpendicular to the XY plane containing the bisector of the angle formed by the two directions of the orthogonal field components Ex and Ey, that is to say of the angle separating the two coupling slots of the OMT, or the angle 26 formed by the two transverse branches 41, 42. The vertex 27 (visible on the figure 4 ) of the elbow of the orientation ring 18 is therefore placed in a plane orthogonal to the XY plane and containing the bisector 25 of the angle 26 between the two orthogonal coupling slots, that is to say the angle formed 26 by the two transverse branches 41, 42. In the case of an OMT with four transverse branches, there are four coupling slots regularly spaced angularly. The bisector 25 then corresponds to that of the angle between two consecutive orthogonal coupling slots, that is to say the bisector of the angle between two consecutive transverse orthogonal branches.

The RF chain described in connection with the Figures 6a , 7a, 7b , has the advantage of having a architecture, monolayer or multilayer, completely planar, all radiofrequency components corresponding to the same frequency band being manufactured by machining in the form of two metal half-shells stacked and assembled together. The manufacture of all radio frequency components by machining provides a very high strength of the RF chain vis-à-vis the performance dispersions related to the manufacture of components. Indeed, all the components corresponding to the same frequency band being located in the same physical layer, all the electrical paths dedicated to the two polarizations of each RF channel are symmetrical and therefore induce the same phase dispersion. Moreover, milling, which is the only machining mode suitable for the manufacture of half-shells, makes it possible to guarantee excellent surface conditions and allows the deposit of a silver coating on the machined parts to allow a reduction ohmic losses of about 30%.

In the case of operation in several different frequency bands, the multilayer structure of the RF chain forms a very compact, very low-cost, multi-band, bipolarization assembly that is compatible with implantation in a network of radiating sources. reduced mesh size and which can be integrated into a support plate common to several RF channels as shown in FIG. figure 2 . The input / output ports 34, 35, 38, 39 of the RF chain can be oriented on the sides, as on the Figures 7a, 7b , or forward or backward, as needed.

As shown in the examples of Figures 8a and 8b , this architecture also allows the manufacture of a sectored radiating network in several independent radiating panels 50a, 50b, 50c, 50d, 50e, each radiating panel consisting of a structural module incorporating a subset of several radiating sources 54 comprising RF chains machined in a matrix in a common support plate 51 to all sources 54 of the subassembly, and independent of the source support plates of the other panels. The RF power supply and output waveguides of the different radiating sources integrated in each panel 50a are then routed in the common support plate to the respective input and output ports 55 which can for example be grouped into one. same place of the corresponding panel. For example, all input and output ports 55 may be aligned next to one another at an edge of the panel. In this case, the manufacture of integrated RF channels in each panel can be pooled, all the RF chains being made by machining in the form of three half-shells stacked and assembled together. This reduces manufacturing costs and reduces losses.

The various radiating panels 50a, 50b, 50c, 50d, 50e are then assembled together to form the radiating network. To facilitate the assembly of the different panels together, the shapes of the cutouts of the different support plates corresponding to each panel are complementary to each other so that they can fit into each other, as shown in FIG. figure 8c . Each panel of the radiating network can then be oriented independently of the other panels. The orientation of the integrated RF channels in each panel is then ensured globally by the orientation of the corresponding panel, then refined individually for each radiating source of the panel via the dedicated orientation ring which ensures the individual orientation of each radiating horn corresponding to each radiating source. The radiating network then forms a faceted assembly, each facet consisting of a radiating panel.

An example of implantation of a radiating network in a multibeam antenna is represented on the figure 9 . The radiating network comprises at least one structural module or at least one radiating panel, the radiating panel comprising a structural module incorporating radiating sources. The radiating grating 60 according to the invention is placed in the focus of a reflector 61 to produce several different beams 1, 2, 3. Each radiating source is oriented individually, via the dedicated orientation ring, according to its location in the radiating network with respect to the reflector.

Although the invention has been described in connection with particular embodiments, it is obvious that it is not limited thereto and that it includes all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims (11)

An antenna structural module incorporating elementary radiating sources, each radiating source comprising an RF radio frequency chain (10) connected to a radiating horn (16), the RF chain (10) having a main waveguide (31) having an axis longitudinal axis arranged perpendicularly to an XY plane and an OMT orthomode transducer (30) having two transverse branches (41, 42) orthogonal to each other, located parallel to the XY plane and coupled perpendicularly to the main waveguide (31) by coupling slots , characterized in that the radiating horn (16) is coupled to an end end (5) of the main waveguide (31) via an angled orientation ring (18) for orienting the radiating horn. (16) in a desired direction different from the longitudinal axis of the main waveguide (31), the elbow of the orientation ring (18) being placed in a plane of symmetry of the RF chain, the plane of symmetry being orthogonal to the XY plane and containing the bisector (25) of the angle (26) formed by the two transverse branches (41,42). Structural module according to claim 1, characterized in that it further comprises a support plate (17) common to all the radiating sources, the RF chains (10) being completely integrated in the support plate (17). Structural module according to claim 2, characterized in that the orientation ring (18) associated with each radiating horn is housed in a dedicated opening in a front face (19) of the support plate (17). Structural module according to claim 2, characterized in that the end (5) of the main waveguide (31) of each RF chain is housed in a dedicated opening in a front face of the support plate (17) and in that the orientation ring (18) associated with each radiating horn is fixed on a front face (19) of the support plate (17), in the extension of the corresponding terminal end (5). Structural module according to one of Claims 1 to 4, characterized in that the orientation ring (18) of each radiating source consists of three mutually integral parts, the three parts consisting of two waveguides. rigid ports (21, 22) having longitudinal axes (24, 23) different and adapted to be respectively connected to a radiating horn and an RF chain, and a localized adaptation waveguide section (20). between the two access waveguides, the adaptation waveguide section (20) forming the elbow of the orientation ring (18). Structural module according to one of claims 1 to 4, characterized in that the orientation ring (18) has a coupling iris. Radiant panel characterized in that it comprises a structural module according to one of the preceding claims. Radiant panel according to Claim 7, characterized in that the radiating sources (54) are machined in a matrix in the common support plate (17, 51) and furthermore comprise respective supply and output waveguides, routed in the common support plate and respectively connected to access (55) input and output grouped next to each other on the radiating panel. Radiant network characterized in that it comprises at least one radiating panel according to claim 8. Radiant network according to claim 9, characterized in that it comprises a plurality of radiating panels (50a, 50b, 50c, 50d, 50e) that can be steered independently of one another. Multibeam antenna characterized in that it comprises at least one radiating network according to one of Claims 9 or 10.

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