EP0006391B1 - Periscopic feed system for two-band antenna - Google Patents

Periscopic feed system for two-band antenna Download PDF

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Publication number
EP0006391B1
EP0006391B1 EP79400411A EP79400411A EP0006391B1 EP 0006391 B1 EP0006391 B1 EP 0006391B1 EP 79400411 A EP79400411 A EP 79400411A EP 79400411 A EP79400411 A EP 79400411A EP 0006391 B1 EP0006391 B1 EP 0006391B1
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EP
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Prior art keywords
axis
mirror
range
feed system
periscopic
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Expired
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EP79400411A
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German (de)
French (fr)
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EP0006391A1 (en
Inventor
Claude Aubry
Daniel Renaud
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
    • H01Q15/0013—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
    • H01Q15/0033—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective used for beam splitting or combining, e.g. acting as a quasi-optical multiplexer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
    • H01Q19/18—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces
    • H01Q19/19—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
    • H01Q19/191—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface wherein the primary active element uses one or more deflecting surfaces, e.g. beam waveguide feeds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/40—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
    • H01Q5/45—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements using two or more feeds in association with a common reflecting, diffracting or refracting device

Definitions

  • the present invention relates to a periscope feed system for a bi-range antenna.
  • a preferred application is found in the use of two frequency ranges on an antenna with frequency reuse by orthogonal polarizations.
  • the antennas with frequency reuse by orthogonal polarizations are antennas operating simultaneously and independently with two orthogonal polarizations. They include a reflector system, of the Cassegrain type for example, a power supply device comprising a primary source and a periscope ensuring the transmission of the wave beam from the source to the reflectors and comprising four mirrors whose curvatures determine the frequency reuse .
  • the entire feeding device and periscope are called the periscopic feeding system.
  • the reflector system is movable along two perpendicular axes.
  • the site and azimuth axes are used, identified in FIG. 1, which represents the classic case of a single-range antenna, respectively by the letters EL and AZ.
  • the supply device comprises a primary source 1 fixed of the corrugated horn type, placed on the axis AZ.
  • the periscope comprises a frame 2, movable around this axis AZ, and four mirrors 3, 4, 5, 6, the mirrors 3 and 6 or 4 and 6 being planar and the mirrors 4 and 5 or 3 and 5 respectively being focusing ( paraboloid or ellipsoid).
  • the microwave wave beam is reflected successively on the mirrors 3, 4, 5 and 6 which are respectively called first, second, third and fourth mirror of the periscope.
  • the arrangement of these mirrors in the periscope is well known for antennas with frequency reuse. It is nevertheless recalled that the first mirror 3 is centered on the azimuth axis, that the mirrors 3, 4, 5 are integral with the frame 2 and therefore movable around the azimuth axis, while the fourth mirror 6 is integral with the system of reflectors, comprising a main reflector 7 and a secondary reflector 8, and therefore mobile around the azimuth axis but also autbur of the site axis. This fourth mirror 6 is centered on the intersection of the azimuth and site axes.
  • the low range is from 4 to 6 GHz and the high range from 11 to 14 GHz.
  • a dielectric mirror is described in a Japanese document by Koyama "A wide band dielectrical filter for the antenna and feed system for the 4-6 GHz, 17-30 GHz domestic satellite communication system published in” The Summaries of papers of International Symposium on Antennas and Propagation, September 1-3, 1971, SENDAI, Japan.
  • the reflector system 7 and 8 in FIG. 2 remains unchanged because the example of the Cassegrain antenna considered above is kept.
  • the dichroic mirror 30 playing for him the same role as the plane mirror 3 of the figure 1 ; it is a primary source, for example a corrugated horn 1, located on the azimuth axis.
  • the dichroic mirror 30 is a high pass mirror whose cut-off frequency is as it reflects the waves emitted by the horn 7. These waves therefore follow a path identical to that followed by the waves in the single-range antenna.
  • the supply device 50 of the high range comprises a primary source 10 and a focusing mirror 9.
  • the primary source 10 for example a corrugated horn is parallel to the azimuth axis, directed upwards.
  • the mirror 9 is located so that the beam of waves of the high range which it reflects is directed towards the dichroic mirror 30 and is superimposed on the beam reflected of the low range beyond this mirror.
  • the purity of the polarization is obtained, as in the mono-range antenna, by compensation between the crossed polarizations created by each of the two focusing mirrors 4 and 5. It suffices that the central regions of these mirrors are produced with increased precision to obtain the same effect for the high range as for the low range.
  • An object of the invention is a rearrangement of the primary sources and the mirrors, executed in such a way that the sources are fixed as well as the mirror making it possible to superimpose or separate waves from the two sources, with preservation of the purity of the polarization .
  • the power supply system for bi-range antenna with frequency reuse and conservation of polarization purity comprising a reflector of the Cassegrain type mobile around an azimuth axis and a site axis, a periscope comprising at least four mirrors, a dichroic mirror centered on the azimuth axis and two excitation sources in frequency ranges, respectively high and low, supplying the antenna with its periscope via the dichroic mirror, is characterized in that the excitation sources are fixed and that the dichroic mirror is fixed and placed under the periscope.
  • periscope 60 with four mirrors 3, 4, 5 and 6, similar to that of the single-range antenna of Figure 1. This periscope feeds a reflector system of the Cassegrain type not shown in the figure .
  • a separating device fixed, in the form of a dichroic mirror 30.
  • This mirror is centered on the azimuth axis AZ and parallel to the first mirror 3 of the periscope; on transmission, it ensures the recombination of the two beams of waves emitted by two supply devices respectively low range 40 and high range 50 and their separation on reception.
  • the dichroic mirror 30 is therefore of the “high-pass” type, that is to say it is transparent for the high range and reflective for the low range.
  • the device 50 for excitation of the high range sends a wave train along the fixed axis AZ; this wave train crosses the mirror 30 and continues its path along the axis AZ towards the mirror 3.
  • This excitation device 50 comprises a primary source, for example a corrugated horn 10, supplied by a waveguide not shown in the figure, and a number of mirrors.
  • a primary source for example a corrugated horn 10, supplied by a waveguide not shown in the figure, and a number of mirrors.
  • it comprises a corrugated horn 10 and a focusing mirror 11.
  • the horn 10 is located parallel to the axis EL; the mirror 11 has its center on the axis AZ and has as normal at this point a parallel to the first bisector of the reference frame (EL-AZ), so that the wave beam reflected by this mirror has as propagation direction l 'axis AZ.
  • the curvature of the mirror 11 and the respective distances of this mirror, the horn 10 and the dichroic mirror 30 are such that there is a field concentration at the same time as a plane wave surface at the level of this dichroic mirror. .
  • the low range excitation device 40 sends a wave train in a direction such that after reflection on the mirror 30, the reflected beam propagates along the axis AZ, then superimposing itself on the beam of the high range.
  • the wave train emitted by the device 40 is therefore distributed around an axis AA 'parallel to the axis EL and passing through the center of the dichroic mirror 30.
  • This excitation device 40 comprises in the particular case of FIG. 3, a primary source, in this case, a corrugated horn 1 supplied by a waveguide not shown in the figure, and two focusing mirrors 12 and 13.
  • the mirror 13 is centered on the axis AA '.
  • the mirror 12 is centered on a parallel to the azimuth axis passing through the center of the mirror 13.
  • These mirrors 12 and 13 are further such that they compensate for the cross polarization which is likely to occur during the transmission of the signals and which then generates a harmful intermodulation.
  • the corrugated horn has for axis of symmetry and therefore for mean direction of radiation an axis parallel to the elevation axis and passing through the center of the mirror 12.
  • this low range excitation device is described in the case where its plane of symmetry is vertical. By subjecting this device to a rotation about the axis AA ′, it is possible, without drawback, to make this plane horizontal.
  • the geometric parameters (distance, curvature of the focusing mirrors) of the two excitation devices as well as the distances from the dichroic mirror 30 to each of these two excitation devices and to the first mirror of the periscope are determined according to the principles, well known in the art. prior art, periscopic antenna feed systems with frequency reuse. Remember that these parameters are.
  • a periscopic feeding system as described above therefore allows the transformation of an antenna with mono-range operation into an antenna with bi-range operation and this without modifying the basic structure of the periscope proper with the innovation, however, of having the dichroic mirror on the outside of the periscope and make it fixed and also make each of the excitation devices fixed.
  • the low range covers for example frequencies going from 3.7 to 6.4 GHz and the high range from 11 to 14.5 GHz.
  • the range used by conventional mono-range antennas corresponds to what has been called low range; it is therefore on it that the most severe standards weigh in a bi-range antenna;
  • the excitation device 40 adopted in the above description makes it possible, as has been said, thanks to the polarization compensation which it provides by the use of the two focusing mirrors 12 and 13 to maintain the polarization purity of the common periscope for this frequency range.
  • the same excitation device with two focusing mirrors could also be used for the high range in case the standards required are as strict as for the low range.

Description

La présente invention a trait à un système d'alimentation périscopique pour antenne bi-gamme.The present invention relates to a periscope feed system for a bi-range antenna.

Une application privilégiée se trouve dans l'utilisation de deux gammes de fréquences sur une antenne à réutilisation de fréquence par polarisations orthogonales.A preferred application is found in the use of two frequency ranges on an antenna with frequency reuse by orthogonal polarizations.

On sait, d'une part, que les antennes à réutilisation de fréquence par polarisations orthogonales sont des antennes opérant simultanément et indépendamment avec deux polarisations orthogonales. Elles comprennent un système de réflecteurs, de type Cassegrain par exemple, un dispositif d'alimentation comportant une source primaire et un périscope assurant la transmission du faisceau d'onde de la source aux réflecteurs et comportant quatre miroirs dont les courbures déterminent la réutilisation de fréquence. On appelle système d'alimentation périscopique l'ensemble du dispositif d'alimentation et du périscope.It is known, on the one hand, that the antennas with frequency reuse by orthogonal polarizations are antennas operating simultaneously and independently with two orthogonal polarizations. They include a reflector system, of the Cassegrain type for example, a power supply device comprising a primary source and a periscope ensuring the transmission of the wave beam from the source to the reflectors and comprising four mirrors whose curvatures determine the frequency reuse . The entire feeding device and periscope are called the periscopic feeding system.

Le système de réflecteurs est mobile suivant deux axes perpendiculaires. On se sert dans la suite de cette description des axes site et azimut, repérés sur la figure 1, qui représente le cas classique d'une antenne mono-gamme, respectivement par les lettres EL et AZ.The reflector system is movable along two perpendicular axes. In the following description, the site and azimuth axes are used, identified in FIG. 1, which represents the classic case of a single-range antenna, respectively by the letters EL and AZ.

Dans l'exemple représenté figure 1, le dispositif d'alimentation comprend une source primaire 1 fixe du type cornet corrugué, placée sur l'axe AZ. Le périscope comporte un bâti 2, mobile autour de cet axe AZ, et quatre miroirs 3, 4, 5, 6, les miroirs 3 et 6 ou 4 et 6 étant plans et les miroirs 4 et 5 ou 3 et 5 respectivement étant focalisants (paraboloïde ou ellipsoïde). Le faisceau d'ondes hyperfréquence se réfléchit successivement sur les miroirs 3, 4, 5 et 6 qu'on appelle respectivement premier, deuxième, troisième et quatrième miroir du périscope.In the example shown in FIG. 1, the supply device comprises a primary source 1 fixed of the corrugated horn type, placed on the axis AZ. The periscope comprises a frame 2, movable around this axis AZ, and four mirrors 3, 4, 5, 6, the mirrors 3 and 6 or 4 and 6 being planar and the mirrors 4 and 5 or 3 and 5 respectively being focusing ( paraboloid or ellipsoid). The microwave wave beam is reflected successively on the mirrors 3, 4, 5 and 6 which are respectively called first, second, third and fourth mirror of the periscope.

La disposition de ces miroirs dans le périscope est bien connue pour les antennes à réutilisation de fréquence. On rappelle néanmoins que le premier miroir 3 est centré sur l'axe azimut, que les miroirs 3, 4, 5 sont solidaires du bâti 2 et donc mobiles autour de l'axe azimut, tandis que le quatrième miroir 6 est solidaire du système de réflecteurs, comportant un réflecteur principal 7 et un réflecteur secondaire 8, et donc mobile autour de l'axe azimut mais aussi autbur de l'axe site. Ce quatrième miroir 6 est centré sur l'intersection des axes azimut et site.The arrangement of these mirrors in the periscope is well known for antennas with frequency reuse. It is nevertheless recalled that the first mirror 3 is centered on the azimuth axis, that the mirrors 3, 4, 5 are integral with the frame 2 and therefore movable around the azimuth axis, while the fourth mirror 6 is integral with the system of reflectors, comprising a main reflector 7 and a secondary reflector 8, and therefore mobile around the azimuth axis but also autbur of the site axis. This fourth mirror 6 is centered on the intersection of the azimuth and site axes.

On sait, d'autre part, que dans le domaine des télécommunications spatiales, il est intéressant d'utiliser une même antenne à réutilisation de fréquence pour deux gammes de fréquence et non plus pour une seule. En particulier il est intéressant d'adjoindre une seconde gamme de fréquences plus élevées à l'antenne mono-gamme décrite plus haut. Cette seconde gamme est appelée gamme haute par opposition à la gamme de fréquence du fonctionnement initial, appelée gamme basse. Dans un exemple de réalisation, la gamme basse est de 4 à 6 GHz et la gamme haute de 11 à 14 GHz. On recherche donc un minimum de transformation de l'antenne mono-gamme décrite plus haut qui permette le double fonctionnement.We know, on the other hand, that in the field of space telecommunications, it is advantageous to use the same antenna with frequency reuse for two frequency ranges and no longer for only one. In particular, it is advantageous to add a second range of higher frequencies to the single-range antenna described above. This second range is called the high range as opposed to the frequency range of the initial operation, called the low range. In an exemplary embodiment, the low range is from 4 to 6 GHz and the high range from 11 to 14 GHz. We therefore seek a minimum of transformation of the mono-range antenna described above which allows dual operation.

Pour ce faire il est nécessaire, dans tous les cas, d'adjoindre à l'antenne un second dispositif d'alimentation qui émette les ondes de la gamme haute. Or il est impossible de placer deux cornets sur l'axe azimut de l'antenne, comme c'est le cas pour le cornet 1 de la figure 1, l'un faisant forcément écran pour l'autre. Si toutefois on voulait conserver cette position coaxiale des cornets, il est nécessaire de prévoir deux miroirs supplémentaires de renvoi comme on peut le voir sur la citation FR-A 2 281 660, ce qui ajouterait à la complexité mécanique du système. Un autre positionnement respectif des deux dispositifs d'alimentation et du périscope doit donc être adopté.To do this it is necessary, in all cases, to add to the antenna a second supply device which emits the waves of the high range. However, it is impossible to place two horns on the azimuth axis of the antenna, as is the case for the horn 1 of FIG. 1, one necessarily forming a screen for the other. If, however, we wanted to keep this coaxial position of the horns, it is necessary to provide two additional deflection mirrors as can be seen in the quote FR-A 2 281 660, which would add to the mechanical complexity of the system. Another respective positioning of the two feeding devices and of the periscope must therefore be adopted.

Selon une réalisation de l'art antérieur, schématisée sur la figure 2, le périscope 60 reste inchangé à l'exception du premier miroir plan 3 qu'on remplace par un miroir dichroïque 30. Ce miroir dichroïque est un dispositif qui est transparent pour une gamme et réfléchissant pour une autre et qui permet ainsi de recombiner deux faisceaux émis séparemment en un seul. Inversement il permet aussi de les séparer. Il existe des structures connues pour ce type de miroir :

  • - une structure en grilles parallèles à mailles rectangulaires de fils métalliques ou de bandes imprimées sur support très mince de type mylar,
  • - une structure en grilles métalliques parallèles percées de fentes en croix,
  • - un réseau de guides d'ondes à la coupure pour une gamme de fréquence et passant pour l'autre,
  • - un miroir diélectrique.
According to an embodiment of the prior art, shown diagrammatically in FIG. 2, the periscope 60 remains unchanged with the exception of the first plane mirror 3 which is replaced by a dichroic mirror 30. This dichroic mirror is a device which is transparent for a range and reflecting for another and which thus makes it possible to recombine two beams emitted separately into one. Conversely, it also makes it possible to separate them. There are known structures for this type of mirror:
  • - a structure in parallel grids with rectangular meshes of metal wires or bands printed on very thin support of mylar type,
  • - a structure in parallel metal grids pierced with cross slits,
  • - a network of waveguides at the cut-off for one frequency range and passing for the other,
  • - a dielectric mirror.

Une réalisation particulière de la première des structures mentionnées est décrite dans un article intitulé « A Quasi-Optical Polarization-Inde- pendant Diplexer... paru dans la revue IEEE de novembre 1976, pages 780-785.A particular embodiment of the first of the structures mentioned is described in an article entitled “A Quasi-Optical Polarization-India- during Diplexer ... published in the IEEE review of November 1976, pages 780-785.

Un miroir diélectrique est décrit dans un document japonais de Koyama « A wide band dielec- tric filter for the antenna and feed system for the 4-6 GHz, 17-30 GHz domestic satellite communication system paru dans « The Summaries of papers of International Symposium on Antennas and Propagation, September 1-3, 1971, SENDAI, Japon.A dielectric mirror is described in a Japanese document by Koyama "A wide band dielectrical filter for the antenna and feed system for the 4-6 GHz, 17-30 GHz domestic satellite communication system published in" The Summaries of papers of International Symposium on Antennas and Propagation, September 1-3, 1971, SENDAI, Japan.

Le système de réflecteurs 7 et 8 de la figure 2 reste inchangé car on conserve l'exemple de l'antenne Cassegrain considéré plus haut.The reflector system 7 and 8 in FIG. 2 remains unchanged because the example of the Cassegrain antenna considered above is kept.

On a deux dispositifs d'alimentation respectivement gamme basse 40 et gamme haute 50 : celui de la gamme basse reste identique à celui de l'antenne mono-gamme, le miroir dichroïque 30 jouant pour lui le même rôle que le miroir plan 3 de la figure 1 ; c'est une source primaire, par exemple un cornet corrugué 1, située sur l'axe azimut. Le miroir dichroïque 30 est un miroir « passe haut dont la fréquence de coupure est telle qu'il réfléchit les ondes émises par le cornet 7. Ces ondes suivent donc un chemin identique à celui que suivent les ondes dans l'antenne mono-gamme.There are two supply devices respectively low range 40 and high range 50: that of the low range remains identical to that of the mono-range antenna, the dichroic mirror 30 playing for him the same role as the plane mirror 3 of the figure 1 ; it is a primary source, for example a corrugated horn 1, located on the azimuth axis. The dichroic mirror 30 is a high pass mirror whose cut-off frequency is as it reflects the waves emitted by the horn 7. These waves therefore follow a path identical to that followed by the waves in the single-range antenna.

Le dispositif d'alimentation 50 de la gamme haute comporte une source primaire 10 et un miroir focalisant 9. La source primaire 10, par exemple un cornet corrugué est parallèle à l'axe azimut, dirigé vers le haut. Le miroir 9 est situé de telle sorte que le faisceau d'ondes de la gamme haute qu'il réfléchit est dirigé vers le miroir dichroïque 30 et se superpose au faisceau réfléchi de la gamme basse au-delà de ce miroir.The supply device 50 of the high range comprises a primary source 10 and a focusing mirror 9. The primary source 10, for example a corrugated horn is parallel to the azimuth axis, directed upwards. The mirror 9 is located so that the beam of waves of the high range which it reflects is directed towards the dichroic mirror 30 and is superimposed on the beam reflected of the low range beyond this mirror.

En jouant sur les distances respectives de la source 10, du miroir focalisant 9 et du miroir dichroïque 30, ainsi que sur la courbure du miroir 9, on obtient dans la région quasi-commune aux deux gammes où est disposé le miroir dichroïque 30, une concentration du champ en même temps qu'une surface d'onde plane pour la gamme haute. Ces conditions sont également réalisées de façon analogue pour la gamme basse.By playing on the respective distances of the source 10, of the focusing mirror 9 and of the dichroic mirror 30, as well as on the curvature of the mirror 9, one obtains in the region almost common to the two ranges where the dichroic mirror 30 is arranged, a field concentration at the same time as a plane wave surface for the high range. These conditions are also fulfilled in a similar manner for the low range.

Ces moyens étant réunis, la pureté de la polarisation est obtenue, comme dans l'antenne mono-gamme, par compensation entre les polarisations croisées créées par chacun des deux miroirs focalisants 4 et 5. Il suffit que les régions centrales de ces miroirs soient réalisées avec une précision accrue pour obtenir le même effet pour la gamme haute que pour la gamme basse.These means being combined, the purity of the polarization is obtained, as in the mono-range antenna, by compensation between the crossed polarizations created by each of the two focusing mirrors 4 and 5. It suffices that the central regions of these mirrors are produced with increased precision to obtain the same effect for the high range as for the low range.

On voit, sur la figure 2, que lorsque le périscope 60 effectue une rotation autour de l'axe azimut, il est nécessaire que le dispositif d'alimentation 50 de la gamme haute effectue la même rotation ; ce dispositif 50 est donc lié mécaniquement au périscope 60 et la source primaire 10 est mobile. Un des inconvénients majeurs présenté par cette réalisation de l'art réalisation de l'art antérieur réside dans la mobilité de cette source ; en effet, comme elle doit être elle-même alimentée par un guide d'onde non représenté sur la figure, la réalisation de ce dernier conduit à des solutions complexes et onéreuses.It can be seen in FIG. 2 that when the periscope 60 rotates around the azimuth axis, it is necessary for the supply device 50 of the high range to perform the same rotation; this device 50 is therefore mechanically linked to the periscope 60 and the primary source 10 is mobile. One of the major drawbacks presented by this embodiment of the art embodiment of the prior art lies in the mobility of this source; in fact, as it must itself be supplied by a waveguide not shown in the figure, the production of the latter leads to complex and expensive solutions.

Suivant l'invention, on veut définir une antenne bi-gamme du genre décrit précédemment mais qui soit exempte des inconvénients signalés. Un objet de l'invention est un réarrangement des sources primaires et des miroirs, exécuté de façon telle que les sources sont fixes ainsi que le miroir permettant de superposer ou de séparer des ondes issues des deux sources, avec conservation de la pureté de la polarisation.According to the invention, we want to define a bi-range antenna of the kind described above but which is free from the drawbacks mentioned. An object of the invention is a rearrangement of the primary sources and the mirrors, executed in such a way that the sources are fixed as well as the mirror making it possible to superimpose or separate waves from the two sources, with preservation of the purity of the polarization .

Selon l'invention le système d'alimentation pour antenne bi-gamme à réutilisation de fréquence et conservation de la pureté de polarisation, comportant un réflecteur de type Cassegrain mobile autour d'un axe d'azimut et d'un axe de site, un périscope comprenant au moins quatre miroirs, un miroir dichroïque centré sur l'axe d'azimut et deux sources d'excitation dans des gammes de fréquences, respectivement hautes et basses, alimentant l'antenne par son périscope par l'intermédiaire du miroir dichroïque, est caractérisé en ce que les sources d'excitation sont fixes et que le miroir dichroïque est fixe et placé sous le périscope.According to the invention the power supply system for bi-range antenna with frequency reuse and conservation of polarization purity, comprising a reflector of the Cassegrain type mobile around an azimuth axis and a site axis, a periscope comprising at least four mirrors, a dichroic mirror centered on the azimuth axis and two excitation sources in frequency ranges, respectively high and low, supplying the antenna with its periscope via the dichroic mirror, is characterized in that the excitation sources are fixed and that the dichroic mirror is fixed and placed under the periscope.

D'autres avantages et caractéristiques d'un mode particulier de réalisation de l'invention apparaîtront au cours de la description qui suit d'un exemple de cette réalisation donné à l'aide des figures qui représentent :

  • la figure 1, la visualisation schématique d'une antenne mono-gamme et de son système d'alimentation périscopique,
  • la figure 2, le schéma d'un exemple de réalisation de l'art antérieur d'une antenne bi-gamme comportant un système d'alimentation périscopique,
  • la figure 3, le schéma d'un exemple de réalisation d'un système d'alimentation périscopique pour une antenne bi-gamme suivant l'invention.
Other advantages and characteristics of a particular embodiment of the invention will appear during the following description of an example of this embodiment given with the aid of the figures which represent:
  • FIG. 1, the schematic visualization of a mono-range antenna and its periscope feed system,
  • FIG. 2, the diagram of an exemplary embodiment of the prior art of a bi-range antenna comprising a periscope feed system,
  • FIG. 3, the diagram of an exemplary embodiment of a periscopic feeding system for a bi-range antenna according to the invention.

On reconnaît sur la figure 3 un périscope 60 à quatre miroirs 3, 4, 5 et 6, semblables à celui de l'antenne mono-gamme de la figure 1. Ce périscope alimente un système de réflecteur du type Cassegrain non représenté sur la figure.We recognize in Figure 3 a periscope 60 with four mirrors 3, 4, 5 and 6, similar to that of the single-range antenna of Figure 1. This periscope feeds a reflector system of the Cassegrain type not shown in the figure .

Sous le périscope se trouve un dispositif séparateur, fixe, sous la forme d'un miroir dichroïque 30. Ce miroir est centré sur l'axe azimut AZ et parallèle au premier miroir 3 du périscope ; il assure à l'émission la recombinaison des deux faisceaux d'ondes émis par deux dispositifs d'alimentation respectivement gamme basse 40 et gamme haute 50 et leur séparation à la réception.Under the periscope is a separating device, fixed, in the form of a dichroic mirror 30. This mirror is centered on the azimuth axis AZ and parallel to the first mirror 3 of the periscope; on transmission, it ensures the recombination of the two beams of waves emitted by two supply devices respectively low range 40 and high range 50 and their separation on reception.

Ce type de miroir fonctionne toujours mieux à la réflexion qu'à la transmission, si bien qu'il privilégie une gamme par rapport à l'autre. Dans ce cas des télécommunications spatiales, la gamme à privilégier est la gamme basse. Dans l'exemple de réalisation décrit, le miroir dichroïque 30 est donc du type « passe-haut », c'est-à-dire qu'il est transparent pour la gamme haute et réfléchissant pour la gamme basse.This type of mirror always works better at reflection than at transmission, so that it favors one range over the other. In this case of space telecommunications, the range to be favored is the low range. In the embodiment described, the dichroic mirror 30 is therefore of the “high-pass” type, that is to say it is transparent for the high range and reflective for the low range.

Le dispositif 50 d'excitation de la gamme haute envoie un train d'onde selon l'axe fixe AZ ; ce train d'onde traverse le miroir 30 et continue son chemin selon l'axe AZ vers le miroir 3.The device 50 for excitation of the high range sends a wave train along the fixed axis AZ; this wave train crosses the mirror 30 and continues its path along the axis AZ towards the mirror 3.

Ce dispositif d'excitation 50 comprend une source primaire par exemple un cornet corrugué 10, alimenté par un guide d'onde non représenté sur la figure, et un certain nombre de miroirs. Dans le cas représenté sur la figure, il comprend un cornet corrugué 10 et un miroir focalisant 11. Le cornet 10 est situé parallèlement à l'axe EL ; le miroir 11 a son centre sur l'axe AZ et a pour normale en ce point une parallèle à la première bissectrice du repère (EL-AZ), de façon que le faisceau d'onde réfléchi par ce miroir ait pour direction de propagation l'axe AZ. La courbure du miroir 11 et les distances respectives de ce miroir, du cornet 10 et du miroir dichroïque 30 sont telles que l'on a une concentration du champ en même temps qu'une surface d'onde plane au niveau'de ce miroir dichroïque.This excitation device 50 comprises a primary source, for example a corrugated horn 10, supplied by a waveguide not shown in the figure, and a number of mirrors. In the case shown in the figure, it comprises a corrugated horn 10 and a focusing mirror 11. The horn 10 is located parallel to the axis EL; the mirror 11 has its center on the axis AZ and has as normal at this point a parallel to the first bisector of the reference frame (EL-AZ), so that the wave beam reflected by this mirror has as propagation direction l 'axis AZ. The curvature of the mirror 11 and the respective distances of this mirror, the horn 10 and the dichroic mirror 30 are such that there is a field concentration at the same time as a plane wave surface at the level of this dichroic mirror. .

Le dispositif 40 d'excitation de la gamme basse envoie un train d'onde selon une direction telle qu'après réflexion sur le miroir 30, le faisceau réfléchi se propage selon l'axe AZ, se superposant alors au faisceau de la gamme haute. A cet effet, le train d'onde émis par le dispositif 40 est donc réparti autour d'un axe AA' parallèle à l'axe EL et passant par le centre du miroir dichroïque 30.The low range excitation device 40 sends a wave train in a direction such that after reflection on the mirror 30, the reflected beam propagates along the axis AZ, then superimposing itself on the beam of the high range. In this Indeed, the wave train emitted by the device 40 is therefore distributed around an axis AA 'parallel to the axis EL and passing through the center of the dichroic mirror 30.

Ce dispositif d'excitation 40 comprend dans le cas particuliér de la figure 3, une source primaire, en l'occurrence, un cornet corrugué 1 alimenté par un guide d'onde non représenté sur la figure, et deux miroirs focalisants 12 et 13. Le miroir 13 est centré sur l'axe AA'. Le miroir 12 est centré sur une parallèle à l'axe azimut passant par le centre du miroir 13. Ces miroirs 12 et 13 sont de plus tels qu'ils compensent la polarisation croisée qui risque de se produire lors de la transmission des signaux et qui engendre alors une intermodulation préjudiciable. Le cornet corrugué a pour axe de symétrie et donc pour direction moyenne de rayonnement un axe parallèle à l'axe élévation et passant par le centre du miroir 12.This excitation device 40 comprises in the particular case of FIG. 3, a primary source, in this case, a corrugated horn 1 supplied by a waveguide not shown in the figure, and two focusing mirrors 12 and 13. The mirror 13 is centered on the axis AA '. The mirror 12 is centered on a parallel to the azimuth axis passing through the center of the mirror 13. These mirrors 12 and 13 are further such that they compensate for the cross polarization which is likely to occur during the transmission of the signals and which then generates a harmful intermodulation. The corrugated horn has for axis of symmetry and therefore for mean direction of radiation an axis parallel to the elevation axis and passing through the center of the mirror 12.

L'ensemble de ce dispositif d'excitation de la gamme basse est décrit dans le cas où son plan de symétrie est vertical. En faisant subir une rotation autour de l'axe AA' à ce dispositif, on peut, sans inconvénient, rendre ce plan horizontal.The whole of this low range excitation device is described in the case where its plane of symmetry is vertical. By subjecting this device to a rotation about the axis AA ′, it is possible, without drawback, to make this plane horizontal.

Les paramètres géométriques (distance, courbure des miroirs focalisants) des deux dispositifs d'excitation ainsi que les distances du miroir dichroïque 30 à chacun de ces deux dispositifs d'excitation et au premier miroir du périscope sont déterminés selon les principes, bien connus dans l'art antérieur, des systèmes d'alimentation périscopique d'antenne à réutilisation de fréquence. On rappelle que ces paramètres sont . choisis de telle façon que d'une part, dans la région où est disposé le miroir dichroïque 30, on observe pour chacune des deux gammes à la fois une concentration du champ et une surface d'onde plane, et que d'autre part la structure du champ au niveau du miroir dichroïque à l'émission reproduit celle issue du périscope à la réception, ceci permettant d'effectuer la synthèse du champ obtenu à la réception comme à l'émission.The geometric parameters (distance, curvature of the focusing mirrors) of the two excitation devices as well as the distances from the dichroic mirror 30 to each of these two excitation devices and to the first mirror of the periscope are determined according to the principles, well known in the art. prior art, periscopic antenna feed systems with frequency reuse. Remember that these parameters are. chosen in such a way that on the one hand, in the region where the dichroic mirror 30 is arranged, there is observed for each of the two ranges both a field concentration and a plane wave surface, and that on the other hand the structure of the field at the level of the dichroic mirror on the emission reproduces that coming from the periscope on the reception, this making it possible to carry out the synthesis of the field obtained on the reception as on the emission.

Un système d'alimentation périscopique tel que décrit précédemment permet donc la transformation d'une antenne à fonctionnement mono-gamme en une antenne à fonctionnement bi-gamme et ceci sans modification de la structure de base du périscope proprement dit avec la novation toutefois de disposer le miroir dichroïque à l'extérieur du périscope et le rendre fixe et de rendre fixe également chacun des dispositifs d'excitation.A periscopic feeding system as described above therefore allows the transformation of an antenna with mono-range operation into an antenna with bi-range operation and this without modifying the basic structure of the periscope proper with the innovation, however, of having the dichroic mirror on the outside of the periscope and make it fixed and also make each of the excitation devices fixed.

Une application privilégiée se trouve dans le domaine des télécommunications spatiales où la gamme basse couvre par exemple des fréquences allant de 3,7 à 6,4 GHz et la gamme haute de 11 à 14,5 GHz. Dans ce domaine la gamme utilisée par les antennes classiques mono-gamme correspond à ce que l'on a appelé gamme basse ; c'est donc sur elle que pèsent dans une antenne bi-gamme les normes les plus sévères ; le dispositif d'excitation 40 adopté dans la description qui précède permet comme cela a été dit, grâce à la compensation de polarisation qu'il procure par l'utilisation des deux miroirs focalisants 12 et 13 de conserver la pureté de polarisation du périscope commun pour cette gamme de fréquence. Un même dispositif d'excitation à deux miroirs focalisants pourrait être aussi utilisé pour la gamme haute au cas où les normes exigées seraient aussi sévères que pour la gamme basse.A preferred application is found in the field of space telecommunications where the low range covers for example frequencies going from 3.7 to 6.4 GHz and the high range from 11 to 14.5 GHz. In this area, the range used by conventional mono-range antennas corresponds to what has been called low range; it is therefore on it that the most severe standards weigh in a bi-range antenna; the excitation device 40 adopted in the above description makes it possible, as has been said, thanks to the polarization compensation which it provides by the use of the two focusing mirrors 12 and 13 to maintain the polarization purity of the common periscope for this frequency range. The same excitation device with two focusing mirrors could also be used for the high range in case the standards required are as strict as for the low range.

Claims (6)

1. A double range antenna feed system which permits the frequency reuse and the conservation of the polarization purity, comprising a Cassegrain-type reflector (7, 8) which is movable around an azimut axis (AZ) and an elevation axis (EL), a periscope (60) with four mirrors (3 to 6), a semi-transparent mirror (30) centered on the azimut axis, and two excitation sources (50 and 40 respectively) for the high and the low frequency range, these sources feeding the antenna via its periscope and the semi-transparent mirror, characterized in that the excitation sources (40, 50) are fixed and that the semi-transparent mirror (30) is fixed and is placed underneath the periscope (60).
2. A periscopic feed system according to claim 1, characterized in that the excitation device (50) for the higher range for which the semi-transparent mirror (30) is transparent, sends out a wave train along the azimut axis, and that the excitation device (40) for the lower range for which the semi-transparent mirror (30) is a reflector, sends out a wave train along an axis (AA') which is parallel to the elevation axis (EL) and which passes through the center of said semi-transparent mirror (30).
3. A periscopic feed system according to one of the claims 1 and 2, characterized in that the excitation device (40) for the lower range comprises a primary source (1) and a device for conserving the polarization purity constituted by two focussing mirrors (12 and 13).
4. A periscopic feed system according to claim 3, characterized in that the primary source (1) is constituted by a corrugated horn, the symmetry axis and the mean propagation direction of which are parallel to the elevation axis (EL) and pass through the center of one of the focussing mirrors (12).
5. A periscopic feed system according to claim 2, characterized in that the excitation device (50) for the higher range comprises a primary source (10) and a focussing mirror (11) which is centered on the azimut axis (AZ).
6. A periscopic feed system according to claim 5, characterized in that the primary source (10) is a corrugated horn having a symmetry axis which is parallel to the elevation axis (EL) and passes through the center of the focussing mirror (11).
EP79400411A 1978-06-20 1979-06-20 Periscopic feed system for two-band antenna Expired EP0006391B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7818408 1978-06-20
FR7818408A FR2429505A1 (en) 1978-06-20 1978-06-20 PERISCOPIC FEEDING SYSTEM FOR TWO-RANGE ANTENNA

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EP0006391A1 EP0006391A1 (en) 1980-01-09
EP0006391B1 true EP0006391B1 (en) 1983-11-16

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DE2966404D1 (en) 1983-12-22
FR2429505A1 (en) 1980-01-18
FR2429505B1 (en) 1981-11-20
EP0006391A1 (en) 1980-01-09
US4260993A (en) 1981-04-07

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