EP0368121B1 - Electronically scanned antenna - Google Patents

Electronically scanned antenna Download PDF

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Publication number
EP0368121B1
EP0368121B1 EP89120178A EP89120178A EP0368121B1 EP 0368121 B1 EP0368121 B1 EP 0368121B1 EP 89120178 A EP89120178 A EP 89120178A EP 89120178 A EP89120178 A EP 89120178A EP 0368121 B1 EP0368121 B1 EP 0368121B1
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EP
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Prior art keywords
antenna
sources
reflector
elementary
network
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EP89120178A
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German (de)
French (fr)
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EP0368121A1 (en
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Albert Cerro
Michel Coustere
Benoît Hanin
Régis Lenormand
Jean-Philippe Marre
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Alcatel Espace Industries SA
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Alcatel Espace Industries SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
    • H01Q3/2658—Phased-array fed focussing structure

Definitions

  • the invention relates to an electronic scanning antenna.
  • a work entitled "space telecommunications" of the technical and scientific collection of telecommunications in particular in its volume I pages 92 to 94 and pages 259 to 261 describes on the one hand the fact of grouping several antennas, fed simultaneously by the same transmitter with the interposition of power dividers and phase shifters, the radiation characteristics of this group depending both on the diagram of each antenna and on the distribution of powers in amplitude and phase. This property is used to obtain a diagram which could not be obtained with a single radiating source. If, in addition, the characteristics of the power dividers and phase shifters are modified by electronic means, an almost instantaneous modification of the diagram can be obtained.
  • the simplest grouping of radiating sources is the network, in which all the sources are identical and are deduced from each other by any translation. We can therefore have in particular rectilinear or planar networks.
  • This document describes, on the other hand, the use of reflector antennas for the generation of multiple beams, which have the advantage of a low weight and the possibilities of making large radiation surfaces using deployable structures.
  • This type of antenna is generally used when it is desired to generate numerous narrow beams.
  • the illumination system of the reflector is off-center with respect to the latter so as to avoid any blockage of the radiating opening. Indeed, blockage of this opening results in an increase in the level of the secondary lobes, which must be avoided at all costs in this kind of application.
  • the main reflector is for example a paraboloid. Multiple beams are obtained by placing a set of illumination sources in the vicinity of the focal point, each source corresponding to a beam.
  • a versatile array fed reflector antenna comprising a network of elementary sources, a reflector focusing energy (the network being located in the focal area of the reflector), and electronic control comprising amplifiers respectively connected to each source, a beamforming network (BFN), and a switching matrix between the amplifiers and the beamforming network (BFN).
  • JP-A62 203 403 describes a switching matrix and its use to give a single phase shift to a plurality of channels.
  • Document EP-A-340 4294 describes FIGS. 1 to 7 of the present application, which show certain known characteristics of the antenna according to the invention. Compared to this prior art, the invention makes it possible to reduce the consumption of all the amplifiers, while allowing efficient synthesis of beams.
  • the invention makes it possible to optimize the parameters of the configuration of the antenna mentioned above.
  • the invention proposes, for this purpose, an electronic scanning antenna comprising an array (11) of elementary sources (Sj), a reflector (10) focusing energy, and control electronics, the array (11) being located in the focal zone of the reflector (10), characterized in that said antenna further comprises means which make possible the non-simultaneous use of the elementary sources (Sj), and in that the elementary sources (Sj) which are not used simultaneously are grouped into classes (Ci) in which only one source can be active, all the sources of each class (Ci) being connected to a passive combiner (40).
  • the combiner is formed of a set of hybrid junctions whose outputs are combined one by two until the useful output signal (s) are obtained.
  • the supply electronics include a switching device.
  • the proposed solution is of the electronic scanning type. It consists of a network synthesizing the electromagnetic field in the focal area of a reflector.
  • the invention Compared to mechanical solutions, the invention has the advantage of not requiring movement of the source or the reflector. It allows the use of weak focal lengths (compact antenna). It provides several simultaneous connections.
  • the antenna of the invention shown in FIG. 1, comprises an eccentric parabolic reflector 10 supplied by a planar network 11 of sources located in the vicinity of the focal point F of the reflector, the network 12 representing the network of virtual sources corresponding to this network 11
  • FIG. 2 gives an example of several amplitude distributions during displacement in two directions OX and OY at the level of the network 11 of sources.
  • the diameters of the disks carried in FIG. 2 represent the amplitude of the signal received by the various sources of the network.
  • the antenna according to the invention one plays on the amplitude and on the phase of each elementary source; which makes it possible to achieve the optimal synthesis of each elementary source as if it were at the focus F of the reflector.
  • Such an operation makes it possible to produce an antenna whose gain does not depend on the pointing direction, while keeping the reflector 10 and the array 11 of elementary sources fixed.
  • the components corresponding to the real distribution are captured locally. After filtering and amplification, these components are assigned phase terms (by variable phase shifters) in order to cancel their differential phases, and optimally added by a summator made up of variable attenuators and hybrid couplers.
  • the displacement of the maximum amplitude of the field is a function of the scanning angle ⁇ on the one hand, and of the distance from the center of the array to the center of the reflector, on the other hand.
  • the dimension of the network is deduced from the maximum excursion and the amplitude distribution. This distribution varies as a function of ⁇ due to the aberrations.
  • Such a network supply makes it possible to synthesize a field distribution which best harmonizes the electromagnetic field distribution in the region of the focus F of the reflector 10. More precisely, when the antenna receives signals, this implies the optimization of the coefficients d amplitude and relative phase applied to each elementary source of the network, to receive a maximum power coming from a particular direction.
  • the relative amplitude and phase coefficients, which must be applied to the elements of the network, are calculated by the technique well known to those skilled in the art of "adaptation by conjugate complexes". For a maximum power transfer between each elementary source of the network and its surrounding field distribution, the overall field distribution over the opening of the network must be the conjugate of the field distribution in the region of the focus of the reflector.
  • FIG. 3 is shown a first embodiment of the electronics for implementing the antenna according to the invention, in the case of a single received beam.
  • each elementary source Sj there is a first horizontal polarization output H and a second vertical polarization output V, which are both connected to a hybrid coupler 20 in which, after 90 ° phase shift of a signal with respect to time at the other, we obtain a circular polarization sum of the two horizontal and vertical polarizations.
  • the respective signals obtained at the output of the hybrid couplers 20 are entered into a low noise amplification circuit 21, consisting for example of a filter 22 and an amplifier 23 proper, then into a beam forming circuit 24 consisting of an adjustable phase shifter 25 and an adjustable attenuator 26 controlled respectively by a control unit 27.
  • the antenna signals at the output of these circuits beam forming units are entered into a combiner 28 formed of a set of microwave couplers 29, for example hybrid junctions, the outputs of which are combined two by two until the useful output signal F1 corresponding to the beam considered is obtained.
  • the supply electronics In the case of m beams received, the supply electronics have the form shown in FIG. 4.
  • a low noise amplification circuit 21 is located behind each source Sj. After amplification, the signal is divided (35) by the number m of users without significant degradation of the G / T ratio (G being the gain and T the noise temperature).
  • the beam forming circuits 24 then adjust the amplitude and the phase of each of the signals, these signals then being sent to m power combiners 28, a maximum output being obtained after summation.
  • the switching system operates as follows: The active circuits corresponding to elementary sources Sp, Sp + 1, Sp + q in the state N are then assigned to elementary sources Sr, Sr + 1, Sr + q in the N + 1 state.
  • a switching device is arranged between the low noise amplification circuit 21 and the power supply and phase shift circuit 24 so that only the elements which receive significant power are controlled by a large network. reduced, and as a power combiner; only one group of elements, and not the whole network, to be checked for each beam (or each user).
  • the sources Sj followed by their hybrid couplers 20 and their respective low noise amplification circuits 21 are connected to a switching device 31.
  • the q outputs (33) of this switching device 31 are the inputs (34) of a beam forming unit 32, represented in FIG. 7, which corresponds to that represented in FIG. 3, but with a number of circuits lesser. To differentiate these circuits from those represented in FIG. 3, their references have been assigned a '.
  • This third embodiment can equally well be adapted in the case of m beams, a switching device is then used, as shown in FIG. 6; the outputs of these m switching devices are connected to m beam forming units 32.
  • a fourth variant of the antenna according to the invention makes it possible to significantly reduce the number of attenuation and phase shift circuits.
  • This variant is based on the following observation: on the n radiating elements constituting the antenna, a certain number of them are never used simultaneously. They can be grouped into classes C1 to Cq from 2 to (X) reception units (a reception unit comprises a radiating element 20 + a filter 22 + a low noise amplifier 23); so that each unit is used sequentially.
  • each class the reception units are grouped together on a passive combiner 40 made up of identical and balanced couplers 29. If we have determined q classes, we will therefore have q outputs which will be connected to the q inputs of a beam forming unit 32, we will therefore have reduced the number of attenuation and phase shift circuits 24 in the ratio q / n.
  • the radiating element used at a given time is designated by supplying the low noise amplifier 23 which is associated with it.
  • This arrangement having the advantage of reducing the consumption of all of these amplifiers in the q / n ratio.
  • the antenna comprises 126 radiating elements distributed in 29 classes of 2 to 8 elements never working simultaneously.
  • the reduction in the number of attenuation and phase shift units is reduced in a ratio greater than 4, improving the mass and the reliability of the assembly.
  • the figures show an extension of the variant proposed in the case of using the antenna with m users, therefore m simultaneous beams F1 to Fm.
  • FIG. 9 shows a configuration in which the beam splitters 41 are located before the combiners 40.
  • FIG. 10 shows a configuration in which these dividers 41 are located after the combiners 40, which has the advantage of reducing their number in the ratio q / n, but of reducing the possibilities of combinations of the reception units in classes of use. An optimization study can lead to an intermediary between these two configurations.
  • the network 11 of elementary sources is for example a network of printed elements ("patch") on a support, each of these elements being able to constitute a multifrequency antenna, for example dual frequency.

Description

L'invention se rapporte à une antenne à balayage électronique.The invention relates to an electronic scanning antenna.

Un ouvrage intitulé "télécommunications spatiales" de la collection technique et scientifique des télécommunications notamment dans son tome I pages 92 à 94 et pages 259 à 261 (Masson, 1982) décrit d'une part le fait de grouper plusieurs antennes, alimentées simultanément par le même émetteur avec interposition de diviseurs de puissances et de déphaseurs, les caractéristiques de rayonnement de ce groupement dépendant à la fois du diagramme de chaque antenne et de la répartition des puissances en amplitude et phase. Cette propriété est mise à profit pour obtenir un diagramme qui ne pourrait pas être obtenu avec une seule source rayonnante. Si en outre on modifie les caractéristiques des diviseurs de puissance et des déphaseurs par des moyens électroniques, on peut obtenir une modification quasi instantanée du diagramme. Le groupement le plus simple de sources rayonnantes est le réseau, dans lequel toutes les sources sont identiques et se déduisent l'une de l'autre par une translation quelconque. On peut donc avoir en particulier des réseaux rectilignes ou plans.A work entitled "space telecommunications" of the technical and scientific collection of telecommunications in particular in its volume I pages 92 to 94 and pages 259 to 261 (Masson, 1982) describes on the one hand the fact of grouping several antennas, fed simultaneously by the same transmitter with the interposition of power dividers and phase shifters, the radiation characteristics of this group depending both on the diagram of each antenna and on the distribution of powers in amplitude and phase. This property is used to obtain a diagram which could not be obtained with a single radiating source. If, in addition, the characteristics of the power dividers and phase shifters are modified by electronic means, an almost instantaneous modification of the diagram can be obtained. The simplest grouping of radiating sources is the network, in which all the sources are identical and are deduced from each other by any translation. We can therefore have in particular rectilinear or planar networks.

Ce document décrit, d'autre part, l'utilisation d'antennes à réflecteur pour la génération de faisceaux multiples, qui présentent l'avantage d'une faible poids et des possibilités de réalisation de grandes surfaces de rayonnement en utilisant des structures déployables. On fait généralement appel à ce type d'antennes lorsque l'on veut engendrer de nombreux faisceaux étroits. En général le système d'illumination du réflecteur est décentré par rapport à celui-ci de façon à éviter tout blocage de l'ouverture rayonnante. En effet, un blocage de cette ouverture se traduit par un accroissement du niveau des lobes secondaires, ce qu'il faut à tout prix éviter dans ce genre d'application. Le réflecteur principal est par exemple un paraboloïde. Les faisceaux multiples sont obtenus en plaçant un ensemble de sources d'illumination au voisinage du foyer, chaque source correspondant à un faisceau. Du fait qu'on ne peut pas les placer exactement au foyer, l'illumination n'est pas géométriquement parfaite et il se produit des aberrations de phase qui dégradent quelque peu les performances de rayonnement. On observe und déformation du diagramme de rayonnement, des baisses de gain par rapport aux valeurs réalisables au foyer, et des lobes secondaires parasites. Ces dégradations sont d'autant plus importantes que l'on s'écarte du foyer et que la courbure du réflecteur est importante. On doit donc réaliser des réflecteurs aussi "plats" que possible, c'est-à-dire avec un rapport distance focale à diamètre d'ouverture élevé. Ceci conduit à des structures de dimensions importantes qui posent des problèmes de précision et de tenue mécanique. De plus, il peut exister entre les différentes sources des couplages mutuels parasites qui créent des lobes secondaires supplémentaires.This document describes, on the other hand, the use of reflector antennas for the generation of multiple beams, which have the advantage of a low weight and the possibilities of making large radiation surfaces using deployable structures. This type of antenna is generally used when it is desired to generate numerous narrow beams. In general, the illumination system of the reflector is off-center with respect to the latter so as to avoid any blockage of the radiating opening. Indeed, blockage of this opening results in an increase in the level of the secondary lobes, which must be avoided at all costs in this kind of application. The main reflector is for example a paraboloid. Multiple beams are obtained by placing a set of illumination sources in the vicinity of the focal point, each source corresponding to a beam. Because they cannot be placed exactly at the focal point, the illumination is not geometrically perfect and there are phase aberrations which somewhat degrade the radiation performance. We observe und distortion of the radiation pattern, reductions in gain compared to the achievable focal points, and parasitic side lobes. These degradations are all the more important that one moves away from the focal point and that the curvature of the reflector is important. Reflectors must therefore be made as "flat" as possible, that is to say with a focal distance to high aperture diameter ratio. This leads to structures of large dimensions which pose problems of precision and mechanical strength. In addition, there may exist parasitic mutual couplings between the different sources which create additional secondary lobes.

Dans le domaine spatial des applications, qui nécessitent une déflexion électronique de l'onde rayonnée sur un large champ visuel, conduisent à des déviations angulaires de plusieurs largeurs de pinceau. En conséquence, la possibilité de contrôler précisément la forme du diagramme de l'antenne est essentielle. La configuration de ces grandes antennes doit aussi tenir compte de plusieurs aspects système :

  • limitation en volume du satellite, liée à la nécessité pour une antenne de transmettre et de recevoir simultanément ;
  • compatibilité de la facilité d'agencement mécanique sur la plate-forme, et sur le lanceur avant et pendant le fonctionnenent ;
  • bon contrôle thermique ;
  • multiplicité éventuelle des missions et des utilisateurs.
In the spatial field of applications, which require an electronic deflection of the radiated wave over a wide visual field, lead to angular deviations of several brush widths. Therefore, the ability to precisely control the shape of the antenna pattern is essential. The configuration of these large antennas must also take into account several system aspects:
  • volume limitation of the satellite, linked to the need for an antenna to transmit and receive simultaneously;
  • compatibility of the ease of mechanical arrangement on the platform, and on the launcher before and during operation;
  • good thermal control;
  • possible multiplicity of missions and users.

Le document International Symposium Digest Antennas and Propagation, vol. II, 6 juin 1988, Syracuse, NY, pages 502-505 ; R. Lenormand et al. : "A versatile array fed reflector antenna. Part A- reception" décrit une antenne à balayage électronique comprenant un réseau de sources élémentaires, un réflecteur focalisant l'énergie (le réseau étant situé dans la zone focale du réflecteur), et une électronique de commande comprenant des amplificateurs reliés respectivement à chaque source, un réseau de formation de faisceaux (BFN en anglais), et une matrice de commutation entre les amplificateurs et le réseau de formation de faisceau (BFN).The document International Symposium Digest Antennas and Propagation, vol. II, June 6, 1988, Syracuse, NY, pages 502-505; R. Lenormand et al. : "A versatile array fed reflector antenna. Part A-reception" describes an electronic scanning antenna comprising a network of elementary sources, a reflector focusing energy (the network being located in the focal area of the reflector), and electronic control comprising amplifiers respectively connected to each source, a beamforming network (BFN), and a switching matrix between the amplifiers and the beamforming network (BFN).

Le document Patent abstracts of Japan, vol. 12, no. 60, (E-584)(2907), 23 février 1988: JP-A62 203 403 décrit une matrice de commutation et son utilisation pour donner un déphasage unique à une pluralité de voies.The document Patent abstracts of Japan, vol. 12, no. 60, (E-584) (2907), February 23, 1988: JP-A62 203 403 describes a switching matrix and its use to give a single phase shift to a plurality of channels.

Le document EP-A-340 4294, demande européenne au nom de la Demanderesse, déposé pendant la période de priorité de la présente demande, retirée depuis, et publiée après le dépôt européen de la présente demande, appartient à l'état de la technique visé par l'article 54(3) CBE. Ce document décrit une antenne à balayage électronique comprenant un réseau de sources élémentaires, un réflecteur focalisant l'énergie, le réseau étant situé dans la zone focale du réflecteur, et une électronique d'alimentation et de commande comprenant des coupleurs hybrides, des circuits d'amplification reliés respectivement à chaque source, des circuits de formation de faisceaux (BFN en anglais), et un combineur formé de coupleurs hybrides.Document EP-A-340 4294, European application on behalf of the Applicant, filed during the priority period of this application, withdrawn since, and published after the European filing of this application, belongs to the state of the art referred to in Article 54 (3) EPC. This document describes an electronic scanning antenna comprising an array of elementary sources, a reflector focusing energy, the array being located in the focal area of the reflector, and supply and control electronics comprising hybrid couplers, circuits amplification connected respectively to each source, beam forming circuits (BFN in English), and a combiner formed of hybrid couplers.

Le document EP-A-340 4294 décrit les figures 1 à 7 de la présente demande, qui montrent certaines caractéristiques connues de l'antenne selon l'invention. Par rapport à cet art antérieur, l'invention permet de réduire la consommation de l'ensemble des amplificateurs, tout en permettant la synthèse performante de faisceaux.Document EP-A-340 4294 describes FIGS. 1 to 7 of the present application, which show certain known characteristics of the antenna according to the invention. Compared to this prior art, the invention makes it possible to reduce the consumption of all the amplifiers, while allowing efficient synthesis of beams.

L'invention permet d'optimiser les paramètres de la configuration de l'antenne mentionnées ci-dessus.The invention makes it possible to optimize the parameters of the configuration of the antenna mentioned above.

L'invention propose, à cet effet, une antenne à balayage électronique comprenant un réseau (11) de sources élémentaires (Sj), un réflecteur (10) focalisant l'énergie, et une électronique de commande, le réseau (11) étant situé dans la zone focale du réflecteur (10), caractérisée en ce que ladite antenne comprend en outre des moyens qui rendent possible l'utilisation non simultanée des sources élémentaires (Sj), et en ce que les sources élémentaires (Sj) non utilisées simultanément sont regroupées en classes (Ci) dans lesquelles une seule source peut être active, toutes les sources de chaque classe (Ci) étant reliées à un combineur passif (40).The invention proposes, for this purpose, an electronic scanning antenna comprising an array (11) of elementary sources (Sj), a reflector (10) focusing energy, and control electronics, the array (11) being located in the focal zone of the reflector (10), characterized in that said antenna further comprises means which make possible the non-simultaneous use of the elementary sources (Sj), and in that the elementary sources (Sj) which are not used simultaneously are grouped into classes (Ci) in which only one source can be active, all the sources of each class (Ci) being connected to a passive combiner (40).

Selon l'invention, le combineur est formé d' un ensemble de jonctions hybrides dont les sorties sont combinées des à deux jusqu'à obtenir le ou les signaux de sortie utiles.According to the invention, the combiner is formed of a set of hybrid junctions whose outputs are combined one by two until the useful output signal (s) are obtained.

Avantageusement l'électronique d'alimentation comprend un dispositif de commutation.Advantageously, the supply electronics include a switching device.

La solution proposée est du type balayage électronique. Elle est constituée d'un réseau réalisant la synthèse du champ électromagnétique dans la zone focale d'un réflecteur.The proposed solution is of the electronic scanning type. It consists of a network synthesizing the electromagnetic field in the focal area of a reflector.

Par rapport aux solutions mécaniques, l'invention présente l'avantage de ne pas nécessiter de mouvements de la source ou du réflecteur. Elle permet d'utiliser des focales faibles (antenne compacte). Elle assure plusieurs liaisons simultanées.Compared to mechanical solutions, the invention has the advantage of not requiring movement of the source or the reflector. It allows the use of weak focal lengths (compact antenna). It provides several simultaneous connections.

Les avantages par rapport à une solution réseau à rayonnement direct sont les suivantes :

  • . la performance de l'antenne n'est pas liée directement à la dimension totale du réseau,
  • . l'implantation n'est pas obligatoirement sur la face terre du satellite.
The advantages compared to a direct radiation network solution are as follows:
  • . the antenna performance is not directly linked to the total size of the network,
  • . the installation is not necessarily on the earth face of the satellite.

Par rapport à une solution réseau imageur à simple réflecteur, la solution proposée présente les avantages suivants :

  • . la dimension hors tout du réseau est réduite,
  • . l'efficacité antenne est améliorée.
Compared to a single reflector imaging network solution, the proposed solution has the following advantages:
  • . the overall dimension of the network is reduced,
  • . antenna efficiency is improved.

Enfin, si on compare la solution proposée à une solution réseau imageur à double réflecteur, la compacité de l'antenne de l'invention est clairement mise en évidence.Finally, if we compare the proposed solution to an imaging network solution with double reflector, the compactness of the antenna of the invention is clearly highlighted.

Les caractéristiques et avantages de l'invention ressortiront d'ailleurs de la description qui va suivre, à titre d'exemple non limitatif, en référence aux figures annexées sur lesquelles :

  • la figure 1 illustre schématique l'antenne à balayage selon l'invention ;
  • la figure 2 illustre le fonctionnement de l'antenne selon l'invention ;
  • la figure 3 illustre une première réalisation d'une électronique d'alimentation et de commande de l'antenne selon l'invention ;
  • la figure 4 illustre une seconde réalisation d'une électronique d'alimentation et de commande de l'antenne selon l'invention ;
  • les figures 5, 6 et 7 illustrent une troisième réalisation d'une électronique d'alimentation de l'antenne selon l'invention.
  • les figures 8, 9 et 10 illustrent une quatrième réalisation d'une alimentation de l'antenne selon l'invention.
The characteristics and advantages of the invention will become apparent from the description which follows, by way of nonlimiting example, with reference to the appended figures in which:
  • Figure 1 illustrates schematically the scanning antenna according to the invention;
  • Figure 2 illustrates the operation of the antenna according to the invention;
  • FIG. 3 illustrates a first embodiment of an electronics supply and control of the antenna according to the invention;
  • FIG. 4 illustrates a second embodiment of an electronics supply and control of the antenna according to the invention;
  • Figures 5, 6 and 7 illustrate a third embodiment of an antenna feed electronics according to the invention.
  • Figures 8, 9 and 10 illustrate a fourth embodiment of an antenna power supply according to the invention.

L'antenne de l'invention, représentée à la figure 1, comprend un réflecteur parabolique 10 excentré alimenté par un réseau plan 11 de sources situé au voisinage du foyer F du réflecteur, le réseau 12 représentant le réseau de sources virtuelles correspondant à ce réseau 11The antenna of the invention, shown in FIG. 1, comprises an eccentric parabolic reflector 10 supplied by a planar network 11 of sources located in the vicinity of the focal point F of the reflector, the network 12 representing the network of virtual sources corresponding to this network 11

La figure 2 donne un exemple de plusieurs répartitions en amplitude lors de déplacement selon deux directions OX et OY au niveau du réseau 11 de sources.FIG. 2 gives an example of several amplitude distributions during displacement in two directions OX and OY at the level of the network 11 of sources.

Les diamètres des disques portés sur la figure 2 représentent l'amplitude du signal reçu par les différentes sources du réseau.The diameters of the disks carried in FIG. 2 represent the amplitude of the signal received by the various sources of the network.

L'efficacité pour capter ces différentes répartitions d'énergie, lorsque le capteur a une loi de répartition fixe, ne peut être optimale. Il en est de même pour la répartition en phase.The efficiency for capturing these different energy distributions, when the sensor has a fixed distribution law, cannot be optimal. The same is true for phase distribution.

Ainsi si l'on déplace fictivement une source par rapport au foyer du réflecteur on dégrade le rendement de l'antenne.Thus if one fictitiously displaces a source with respect to the focus of the reflector, the efficiency of the antenna is degraded.

Dans l'antenne selon l'invention, on joue sur l'amplitude et sur la phase de chaque source élémentaire ; ce qui permet de réaliser la synthèse optimale de chaque source élémentaire comme si elle était au foyer F du réflecteur.In the antenna according to the invention, one plays on the amplitude and on the phase of each elementary source; which makes it possible to achieve the optimal synthesis of each elementary source as if it were at the focus F of the reflector.

Un tel fonctionnement permet de réaliser une antenne dont le gain ne dépend pas de la direction de pointage, tout en maintenant fixes le réflecteur 10 et le réseau 11 de sources élémentaires.Such an operation makes it possible to produce an antenna whose gain does not depend on the pointing direction, while keeping the reflector 10 and the array 11 of elementary sources fixed.

En utilisant le réseau 11 de sources on capte localement les composantes correspondant à la distribution réelle. Après filtrage et amplification, ces composantes sont affectées de termes de phases (par des déphaseurs variables) en vue d'annuler leurs phases différentielles, et additionnées de manière optimale par un sommateur constitué d'atténuateurs variables et de coupleurs hybrides.By using the network 11 of sources, the components corresponding to the real distribution are captured locally. After filtering and amplification, these components are assigned phase terms (by variable phase shifters) in order to cancel their differential phases, and optimally added by a summator made up of variable attenuators and hybrid couplers.

Le déplacement du maximum d'amplitude du champ est fonction de l'angle ϑ de balayage d'une part, et de la distance du centre du réseau au centre du réflecteur, d'autre part.The displacement of the maximum amplitude of the field is a function of the scanning angle ϑ on the one hand, and of the distance from the center of the array to the center of the reflector, on the other hand.

La dimension du réseau est déduite de l'excursion maximale et de la répartition d'amplitude. Cette répartition varie en fonction de ϑ en raison des aberrations.The dimension of the network is deduced from the maximum excursion and the amplitude distribution. This distribution varies as a function of ϑ due to the aberrations.

Une telle alimentation par réseau permet de synthétiser une distribution de champ qui harmonise au mieux la distribution de champ électromagnétique dans la région du foyer F du réflecteur 10. Plus précisément, quand l'antenne reçoit des signaux, cela implique l'optimisation des coefficients d'amplitude et de phase relatives appliqués à chaque source élémentaire du réseau, pour recevoir une puissance maximale en provenance d'une direction particulière.Such a network supply makes it possible to synthesize a field distribution which best harmonizes the electromagnetic field distribution in the region of the focus F of the reflector 10. More precisely, when the antenna receives signals, this implies the optimization of the coefficients d amplitude and relative phase applied to each elementary source of the network, to receive a maximum power coming from a particular direction.

Les coefficients d'amplitude et de phase relatives, qui doivent être appliqués aux éléments du réseau, sont calculés par la technique bien connue de l'homme de l'art de "l'adaptation par complexes conjugués". Pour un transfert de puissance maximale entre chaque source élémentaire du réseau et sa distribution de champ environnante, la distribution de champ globale sur l'ouverture du réseau doit être le conjugué de la distribution de champ dans la région du foyer du réflecteur.The relative amplitude and phase coefficients, which must be applied to the elements of the network, are calculated by the technique well known to those skilled in the art of "adaptation by conjugate complexes". For a maximum power transfer between each elementary source of the network and its surrounding field distribution, the overall field distribution over the opening of the network must be the conjugate of the field distribution in the region of the focus of the reflector.

Un tel contrôle de l'amplitude et de la phase des sources élémentaires présente de nombreux avantages, puisque en principe, n'importe quelle distribution de champ peut être synthétisée (en dépendance de l'espacement entre sources élémentaires). La restriction habituelle d'un grand ration F/D, F étant la distance focale du réflecteur et D son diamètre, (pour réduire des pertes dues au dépointage) peut être relaxée ce qui permet d'optimiser la position du réseau. Ces caractéristiques ont un impact important sur la forme globale du sous-système antenne ; ainsi, par exemple, le réseau peut être monté directement sur une face de la plate-forme du satellite pour faciliter le contrôle thermique. De plus un faible ration F/D peut être utilisé de manière à disposer le réflecteur près de la plateforme, sans entraîner de pertes de dépointages significatives.Such control of the amplitude and phase of the elementary sources has many advantages, since in principle, any field distribution can be synthesized (depending on the spacing between elementary sources). The usual restriction of a large F / D ration, F being the focal distance of the reflector and D its diameter, (to reduce losses due to deflection) can be relaxed, which makes it possible to optimize the position of the network. These characteristics have a significant impact on the overall shape of the antenna subsystem; thus, for example, the network can be mounted directly on one face of the satellite platform to facilitate thermal control. In addition, a low F / D ration can be used so as to place the reflector near the platform, without causing significant loss of deflection.

A la figure 3 est représentée une première réalisation de l'électronique de mise en oeuvre de l'antenne selon l'invention, dans le cas d'un seul faisceau reçu.In FIG. 3 is shown a first embodiment of the electronics for implementing the antenna according to the invention, in the case of a single received beam.

En sortie de chaque source élémentaire Sj on a une première sortie polarisation horizontale H et une seconde sortie polarisation verticale V, qui sont toutes deux reliées à un coupleur hybride 20 dans lequel, après déphasage de 90° dans le temps d'un signal par rapport à l'autre, on obtient une polarisation circulaire somme des deux polarisations horizontale et verticale.At the output of each elementary source Sj there is a first horizontal polarization output H and a second vertical polarization output V, which are both connected to a hybrid coupler 20 in which, after 90 ° phase shift of a signal with respect to time at the other, we obtain a circular polarization sum of the two horizontal and vertical polarizations.

Les signaux respectifs obtenus en sortie des coupleurs hybrides 20 sont entrés dans un circuit 21 d'amplification faible bruit, constitué par exemple d'un filtre 22 et d'un amplificateur 23 proprement dit, puis dans un circuit 24 de formation de faisceau consitué d'un déphaseur réglable 25 et d'un atténuateur réglable 26 pilotés respectivement par une unité de commande 27. Les signaux antennes en sortie de ces circuits de formation de faisceaux sont entrés dans un combineur 28 formé d'un ensemble de coupleurs hyperfréquences 29, par exemple des jonctions hybrides, dont les sorties sont combinées deux à deux jusqu'à obtenir le signal F1 de sortie utile correspondant au faisceau considéré.The respective signals obtained at the output of the hybrid couplers 20 are entered into a low noise amplification circuit 21, consisting for example of a filter 22 and an amplifier 23 proper, then into a beam forming circuit 24 consisting of an adjustable phase shifter 25 and an adjustable attenuator 26 controlled respectively by a control unit 27. The antenna signals at the output of these circuits beam forming units are entered into a combiner 28 formed of a set of microwave couplers 29, for example hybrid junctions, the outputs of which are combined two by two until the useful output signal F1 corresponding to the beam considered is obtained.

Dans le cas de m faisceaux reçus, l'électronique d'alimentation a la forme représentée à la figure 4.In the case of m beams received, the supply electronics have the form shown in FIG. 4.

Sur cette figure les éléments identiques à ceux représentés sur la figure 3 ont été référencés avec les mêmes numéros.In this figure the elements identical to those shown in Figure 3 have been referenced with the same numbers.

Un circuit 21 d'amplification faible bruit est situé derrière chaque source Sj. Après amplification, le signal est divisé (35) par le nombre m d'utilisateurs sans dégradation significative du ratio G/T (G étant le gain et T la température de bruit).A low noise amplification circuit 21 is located behind each source Sj. After amplification, the signal is divided (35) by the number m of users without significant degradation of the G / T ratio (G being the gain and T the noise temperature).

Les circuits 24 de formation de faisceau ajustent alors l'amplitude et la phase de chacun des signaux, ces signaux étant ensuite envoyés sur m combineurs de puissance 28, une sortie maximum étant obtenue après sommation. On récupère alors m signaux F1... Fm, correspondant à chacun des faisceaux.The beam forming circuits 24 then adjust the amplitude and the phase of each of the signals, these signals then being sent to m power combiners 28, a maximum output being obtained after summation. We then recover m signals F1 ... Fm, corresponding to each of the beams.

Pour limiter le nombre de voies à additionner, on remarque que, pour une direction ϑ donnée, seule une partie du réseau contribue de manière significative à la performance. On peut donc, en utilisant un dispositif de commutation, se contenter d'un sommateur à peu de voies. Pour suivre la trace de la tache sur le réseau, le système de commutation fonctionne comme suit : Les circuits actifs correspondant à des sources élémentaires Sp, Sp+1, Sp+q à l'état N sont affectés ensuite à des sources élémentaires Sr, Sr+1, Sr+q à l'état N+1.To limit the number of channels to add, we note that, for a given direction ϑ, only part of the network contributes significantly to performance. We can therefore, using a switching device, be satisfied with a summator with few channels. To follow the trace of the task on the network, the switching system operates as follows: The active circuits corresponding to elementary sources Sp, Sp + 1, Sp + q in the state N are then assigned to elementary sources Sr, Sr + 1, Sr + q in the N + 1 state.

La poursuite d'un mobile s'effectue alors comme suit :

  • . pour de faibles variations, on actualise les composantes d'adaptation aux champs (amplitude et phase de chaque voie) pour garder le niveau maximal de directivité en direction du mobile,
  • . lorsque le déplacement de la tache a atteint un certain seuil, on commute les voies de manière à garder actifs les éléments contribuant le plus à la performance de gain globale.
The tracking of a mobile is then carried out as follows:
  • . for small variations, the field adaptation components (amplitude and phase of each channel) are updated to keep the maximum level of directivity towards the moving body,
  • . when the movement of the spot has reached a certain threshold, the channels are switched so as to keep active the elements contributing most to the overall gain performance.

Ainsi un dispositif de commutation est disposé entre le circuit 21 d'amplification faible bruit et le circuit 24 d'alimentation et de déphasage de telle façon que seuls les éléments qui reçoivent une puissance significative soient contrôlés par un réseau de taille réduite, et en combineur de puissance ; un groupe d'éléments seulement, et non tout le réseau, devant être contrôlé pour chaque faisceau (ou chaque utilisateur).Thus a switching device is arranged between the low noise amplification circuit 21 and the power supply and phase shift circuit 24 so that only the elements which receive significant power are controlled by a large network. reduced, and as a power combiner; only one group of elements, and not the whole network, to be checked for each beam (or each user).

Une telle variante permet de réduire la masse de façon importante.Such a variant makes it possible to reduce the mass significantly.

Ainsi comme représenté à la figure 5, dans le cas d'un seul faisceau, les sources Sj suivies de leurs coupleurs hybrides 20, de leurs circuits 21 d'amplification faible bruit respectifs sont reliées à un dispositif de commutation 31.Thus, as shown in FIG. 5, in the case of a single beam, the sources Sj followed by their hybrid couplers 20 and their respective low noise amplification circuits 21 are connected to a switching device 31.

Les q sorties (33) de ce dispositif de commutation 31 sont les entrées (34) d'une unité de formation de faisceau 32, représentée à la figure 7, qui correspond à celle représentée à la figure 3, mais avec un nombre de circuits moindre. Pour différencier ces circuits de ceux représentés à la figure 3, on a affecté leurs références d'un '.The q outputs (33) of this switching device 31 are the inputs (34) of a beam forming unit 32, represented in FIG. 7, which corresponds to that represented in FIG. 3, but with a number of circuits lesser. To differentiate these circuits from those represented in FIG. 3, their references have been assigned a '.

Cette troisième réalisation peut, tout aussi bien, être adaptée dans le cas de m faisceaux, on utilise alors un dispositif de commutation, comme représenté figure 6 ; les sorties de ces m dispositifs de commutation sont connectées à m unités de formation de faisceau 32.
Une quatrième variante de l'antenne selon l'invention permet de réduire d'une façon significative le nombre des circuits d'atténuation et de déphasage.This third embodiment can equally well be adapted in the case of m beams, a switching device is then used, as shown in FIG. 6; the outputs of these m switching devices are connected to m beam forming units 32.
A fourth variant of the antenna according to the invention makes it possible to significantly reduce the number of attenuation and phase shift circuits.

Elle consiste à remplacer les dispositifs de commutation 31 par des circuits passifs, ce qui permet de diminuer la complexité et d'améliorer la fiabilité de l'antenne tout en conservant les avantages de la variante utilisant ces circuits de commutation.It consists in replacing the switching devices 31 with passive circuits, which makes it possible to reduce the complexity and improve the reliability of the antenna while retaining the advantages of the variant using these switching circuits.

Cette variante est basée sur l'observation suivante : sur les n éléments rayonnants constituant l'antenne, un certain nombre d'entre eux ne sont jamais utilisés simultanément. Ils peuvent être regroupés dans des classes C1 à Cq de 2 à (X) unités de réception (une unité de réception comprend un élément rayonnant 20 + un filtre 22 + un amplificateur faible bruit 23) ; de telle sorte que chaque unité est utilisée séquentiellement.This variant is based on the following observation: on the n radiating elements constituting the antenna, a certain number of them are never used simultaneously. They can be grouped into classes C1 to Cq from 2 to (X) reception units (a reception unit comprises a radiating element 20 + a filter 22 + a low noise amplifier 23); so that each unit is used sequentially.

Dans chaque classe les unités de réception sont regroupées sur un combineur passif 40 constitué de coupleurs 29 identiques et équilibrés. Si on a déterminé q classes on aura donc q sorties qui seront connectées aux q entrées d'une unité de formation de faisceau 32, on aura donc réduit le nombre de circuits d'atténuation et de déphasage 24 dans le rapport q/n.In each class, the reception units are grouped together on a passive combiner 40 made up of identical and balanced couplers 29. If we have determined q classes, we will therefore have q outputs which will be connected to the q inputs of a beam forming unit 32, we will therefore have reduced the number of attenuation and phase shift circuits 24 in the ratio q / n.

Pour chaque classe Ci, l'élément rayonnant utilisé à un instant donné est désigné en alimentant l'amplificateur faible bruit 23 qui lui est associé. Cette disposition ayant pour avantage de réduire la consommation de l'ensemble de ces amplificateurs dans le rapport q/n.For each class Ci, the radiating element used at a given time is designated by supplying the low noise amplifier 23 which is associated with it. This arrangement having the advantage of reducing the consumption of all of these amplifiers in the q / n ratio.

Dans l'application ci-après citée à titre d'exemple, l'antenne comprend 126 éléments rayonnants répartis en 29 classes de 2 à 8 éléments ne travaillant jamais simultanément.In the application below cited by way of example, the antenna comprises 126 radiating elements distributed in 29 classes of 2 to 8 elements never working simultaneously.

La réduction du nombre d'unité d'atténuation et déphasage est réduite dans un rapport supérieur à 4 en amélioration la masse et la fiabilité de l'ensemble.The reduction in the number of attenuation and phase shift units is reduced in a ratio greater than 4, improving the mass and the reliability of the assembly.

Les figures présentent une extension de la variante proposée dans le cas d'utilisation de l'antenne avec m utilisateurs donc m faisceaux simultanés F1 à Fm.The figures show an extension of the variant proposed in the case of using the antenna with m users, therefore m simultaneous beams F1 to Fm.

La figure 9 montre une configuration dans laquelle les diviseurs de faisceaux 41 sont situés avant les combineurs 40.FIG. 9 shows a configuration in which the beam splitters 41 are located before the combiners 40.

La figure 10 montre une configuration dans laquelle ces diviseurs 41 sont situés après les combineurs 40, ce qui présente l'avantage de réduire leur nombre dans le rapport q/n, mais de réduire les possibilités de combinaisons des unités de réception en classes d'utilisation. Une étude d'optimisation peut conduire à un intermédiaire entre ces deux configurations.FIG. 10 shows a configuration in which these dividers 41 are located after the combiners 40, which has the advantage of reducing their number in the ratio q / n, but of reducing the possibilities of combinations of the reception units in classes of use. An optimization study can lead to an intermediary between these two configurations.

Le fonctionnement de l'antenne à balayage électronique selon l'invention a été décrit jusqu'à présent pour la réception de faisceaux, mais il est tout aussi valable dans un fonctionnement en émission : mais dans ce cas les filtres 22 et les amplificateurs faible bruit 23 représentés aux figures 2, 3, 5 et 7 deviennent des amplificateurs de puissance.The operation of the electronic scanning antenna according to the invention has so far been described for the reception of beams, but it is just as valid in transmission operation: but in this case the filters 22 and the low noise amplifiers 23 shown in Figures 2, 3, 5 and 7 become power amplifiers.

Le réseau 11 de sources élémentaires est par exemple un réseau d'éléments imprimés ("patch") sur un support, chacun de ces éléments pouvant constituer une antenne multifréquence, par exemple bifréquence.The network 11 of elementary sources is for example a network of printed elements ("patch") on a support, each of these elements being able to constitute a multifrequency antenna, for example dual frequency.

Claims (6)

  1. An electronically scanned antenna comprising an array (11) of elementary sources (Sj), an energy-focusing reflector (10), and control electronics, with the array (11) being situated in the focal zone of the reflector (10), characterized in that the said antenna further comprises means making possible the non-simultaneous use of elementary sources (Sj) and in that the elementary sources which are not used simultaneously are grouped together in classes (Ci) in which only one source can be active at a time, with all of the sources in each class (Ci) being interconnected by a passive combiner (40) for that class.
  2. An antenna according to claim 1, operating on reception, characterized in that the said means designate the elementary source (Sj) used in feeding the low noise amplifier associated therewith.
  3. An antenna according to claim 1, operating on transmit, characterized in that the said means designate the elementary source (Sj) used in feeding the power component associated therewith.
  4. An antenna according to claim 1, characterized in that the combiner (40) is constituted by a set of microwave couplers (29) whose outputs are combined in pairs to obtain a useful output signal.
  5. An antenna according to claim 1, characterized in that the beam dividers (41) are situated immediately before the combiners (40).
  6. An antenna according to claim 1, characterized in that beam dividers (41) are situated immediately after the combiners (40).
EP89120178A 1988-11-03 1989-10-31 Electronically scanned antenna Expired - Lifetime EP0368121B1 (en)

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FR8814330A FR2638573B1 (en) 1988-11-03 1988-11-03 ELECTRONIC SCANNING ANTENNA
FR8814330 1988-11-03

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US5038147A (en) 1991-08-06
FR2638573B1 (en) 1991-06-14
JPH02179103A (en) 1990-07-12
DE68910784D1 (en) 1993-12-23
DE68910784T2 (en) 1994-03-31
EP0368121A1 (en) 1990-05-16
JP2776918B2 (en) 1998-07-16
CA2002108C (en) 1994-03-08
FR2638573A1 (en) 1990-05-04
CA2002108A1 (en) 1990-05-03

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