EP0432034A1 - Device for spatially selective absorption of electro-magnetic waves for an ultra-high frequency lens - Google Patents

Device for spatially selective absorption of electro-magnetic waves for an ultra-high frequency lens Download PDF

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Publication number
EP0432034A1
EP0432034A1 EP90403443A EP90403443A EP0432034A1 EP 0432034 A1 EP0432034 A1 EP 0432034A1 EP 90403443 A EP90403443 A EP 90403443A EP 90403443 A EP90403443 A EP 90403443A EP 0432034 A1 EP0432034 A1 EP 0432034A1
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European Patent Office
Prior art keywords
lens
discontinuity
phase
planes
resistors
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EP90403443A
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German (de)
French (fr)
Inventor
Gérard Collignon
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Thomson CSF Radant
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Thomson CSF Radant
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/001—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems for modifying the directional characteristic of an aerial
    • 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
    • H01Q3/44—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 electric or magnetic characteristics of reflecting, refracting, or diffracting devices associated with the radiating element
    • H01Q3/46—Active lenses or reflecting arrays

Definitions

  • the subject of the present invention is a device intended to be used in a microwave lens; it is more particularly intended to absorb the parasitic reflections which occur under high incidence.
  • a microwave lens is used which is placed in front of a source providing it with an electromagnetic wave.
  • the lens described in the above patent is formed by a stack of phase shifters separated by conducting planes, each phase shifter itself being constituted by a stack of panels produced according to the direction of propagation of the wave.
  • the wave emerging from the lens makes, with its initial direction, an angle ⁇ , said angle of incidence, which is a function of the commands applied to the different phase shifters.
  • the present invention relates to a device intended for the absorption of these multiple reflections at the level of the entry face of the lens, device which is spatially selective in order to absorb only the multiple reflections and not to disturb the useful wave.
  • the subject of the invention is an absorption device for a microwave lens as defined in claim 1.
  • FIG. 1 therefore schematically represents the microwave lens described in the aforementioned patent.
  • This lens receives an incident energy illustrated by an arrow 10, propagating in a direction OZ and whose electric field is directed along an axis OY, normal to the previous one.
  • the lens consists of a plurality of phase shifters D, stacked along the axis OY and separated by conductive planes C, which extend substantially perpendicular to the axis OY; the space between two planes C is hereinafter called either phase shifter or channel.
  • Each of the phase shifters prints a phase shift whose value is electrically controllable to the microwave wave which passes through it.
  • the wave emerging from the lens illustrated by an arrow 11, then makes in the plane YOZ an angle ⁇ , said angle of incidence, with its initial direction OZ; the value of the angle ⁇ is, as is known, a function of the value of the phase shifts introduced by each of the phase shifters.
  • the entry face F E of the lens located on the side of the incident energy 10
  • the exit face F S located on the side of the wave. emerging 11.
  • Each of the phase shifters D is constituted by a set of panels P, arranged parallel to each other and perpendicular to the direction OZ of energy propagation.
  • FIG. 2 is the diagram of an embodiment of a phase shift panel P used in the lens of FIG. 1.
  • This panel P comprises an insulating substrate 20 extending in a plane XOY perpendicular to the direction OZ.
  • wires F D each carrying a certain number of diodes D, for example two in the figure.
  • the diode wires F D are arranged parallel to the direction of the electric field of the incident wave, that is to say to the axis OY.
  • the bias voltage of the diodes D is brought to the diodes of the panel P by two control wires F C ′ connecting all of the diode wires F D and arranged parallel to the axis OX.
  • the wires F C and F D are preferably produced in the form of conductors printed on the substrate 20.
  • phase shifter D By arranging a plurality of panels P along the axis OZ and controlling them independently of one another, a phase shifter D is formed, the number of distinct values of possible phase shifts depends on the number of panels.
  • FIG. 3 represents a first embodiment of the device according to the invention.
  • a conducting plane C extending along the plane XOZ, constituted for example by a metal plate.
  • the traces, parallel to the axis OX, of the phase-shifting panels P have been illustrated by dashed lines.
  • an electrical discontinuity F is produced in each of the conducting planes C, in the form of a slot extending along the axis OX between the entry face F E of the lens, at a distance d thereof, and the first of the phase shift panels P. Between the two edges of the slot F, of width e , are electrically connected resistors R, arranged at a pitch p.
  • the waves present in the adjacent channels are parasitic waves resulting from multiple reflections as explained above, they have passed through the phase-shift panels at least twice and then exhibit, from one channel to the other, a phase shift relative.
  • the currents created by these waves in the conducting planes no longer cancel each other out until added when the phase shift reaches 180 °.
  • these currents are then absorbed by the resistors R, the geometry of the assembly, that is to say the distance (d) from the slot F to the input face F E , the pitch ( p) resistors, and the width (e) of the slit, in particular, as well as the value of the resistors, being optimized so that the absorption is maximum for the usual values of phase shift of the parasitic waves.
  • the values of the different parameters can be obtained by calculation, taking place in the case where the waves propagating in two adjacent channels are in phase opposition and by classically writing the equivalent circuit of the device and adding the fact that there n there are no reflections, that is to say that the circuit is adapted and that its impedance is equal to that of the wave, and / or experimentally.
  • a device has been developed with the following values: a distance d of the order of a quarter of the wavelength of the wave passing through the lens, or a multiple thereof. this; a pitch p less than half a wavelength and a thickness e of the order of a tenth of a wavelength.
  • FIG. 4 schematically represents a second embodiment of the device according to the invention.
  • a fragment of a conductive plane C This is produced by a conductive deposit 41 on both sides of an insulating substrate 40, for example of the type used to make the cards of printed circuits.
  • the electrical discontinuity F, or slot, in the conductive plane is constituted here by an absence of conductive deposit, on the two faces of the substrate 40.
  • the resistors R of FIG. 3 are, in this embodiment, produced using discrete components 42, deposited on the two faces of the insulating substrate 40 and connected on either side to the metal deposits 41, as illustrated for the upper side in the figure.
  • the determination of the parameters of the absorption device according to the invention takes account of the fact that the device here comprises two series of resistances and no longer just one, as in the case of FIG. 3. As a first approximation, this may translate for the equivalent circuit by the presence of two resistors in parallel instead of one.
  • FIG. 5 represents a third embodiment of the device according to the invention.
  • resistors R of FIG. 3 are here produced by a continuous deposition, on each of the faces of the plane C, of an electrically resistive material 52 on the substrate 40, at the level of the slot F and overflowing on both sides on the conductive layer 41.
  • This material 52 may for example be a screen-printed ink such as those which are used for the production of resistors in the technique of hybrid circuits.
  • FIG. 6 schematically represents an example of application of the device according to the invention.
  • L2 designates a microwave lens as described in Figures 1 and 2 above.
  • C 2 ′ conductive planes
  • a slot 60 and a dotted rectangle have illustrated the slot and the resistances produced in each of the conductive planes C2 on the side of the input face F E2 of the lens L2; it should be noted that the conducting planes C arranged at the ends of the stack forming the lens do not require an absorbent device 60.
  • the lens L2 does not receive the energy which comes directly from a microwave source but an energy which has already undergone a deflection in the XOZ plane using a first lens L1, analogous to the lens L2 but whose conductive planes extend along the YOZ plane.
  • the lens L1 is advantageously also provided with an absorption device according to the invention (not visible in the figure).
  • the two lenses are separated by a polarization rotation grid G R ′ intended to rotate the polarization of the wave emerging from the lens L1 by 90 °, so that it is perpendicular to the conducting planes C2.
  • the lens L2 is further followed by a polarization switching grid G C ′ which either transmits the wave which it receives without modifying its polarization, or alternatively rotates the polarization of l 'wave.
  • the lens L1 further comprises integrated means for generating a microwave wave in each channel; in this case the absorption device according to the invention is disposed between the generation means and the phase shift panels.

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Abstract

The subject of the invention is a device intended for selectively absorbing the electromagnetic waves emanating from multiple reflections in an ultra-high frequency lens. <??>In an antenna of the type including a source of energy and a lens, the lens consisting of a plurality of parallel channels separated by conducting planes (C), the device consists in producing a slot (F) in each of the conducting planes, and arranged on the entrance face (FE) side of the lens, and includes localised or distributed resistors (R) connecting the two edges of the slot, and the geometry of the assembly and the values of the resistors are such that the waves emanating from multiple reflections are absorbed by the resistors. <IMAGE>

Description

La présente invention a pour objet un dispositif destiné à être utilisé dans une lentille hyperfréquence; il est plus particulièrement destiné à absorber les réflexions parasites qui se produisent sous incidence élevée.The subject of the present invention is a device intended to be used in a microwave lens; it is more particularly intended to absorb the parasitic reflections which occur under high incidence.

Dans une antenne par exemple du type de celle qui est décrite dans le brevet français n° 2.469.808, on utilise une lentille hyperfréquence disposée devant une source lui fournissant une onde électromagnétique. La lentille décrite dans le brevet ci-dessus est formée d'un empilement de déphaseurs séparés par des plans conducteurs, chaque déphaseur étant lui-même constitué par un empilement de panneaux réalisé selon la direction de propagation de l'onde. L'onde émergeant de la lentille fait, avec sa direction initiale, un angle ϑ, dit angle d'incidence, qui est fonction des commandes appliquées aux différents déphaseurs.In an antenna, for example of the type described in French patent no. 2,469,808, a microwave lens is used which is placed in front of a source providing it with an electromagnetic wave. The lens described in the above patent is formed by a stack of phase shifters separated by conducting planes, each phase shifter itself being constituted by a stack of panels produced according to the direction of propagation of the wave. The wave emerging from the lens makes, with its initial direction, an angle ϑ, said angle of incidence, which is a function of the commands applied to the different phase shifters.

Lorsque l'angle d'incidence devient important, il apparaît des réflexions parasites de l'onde hyperfréquence sur la face de sortie de la lentille. Cette onde réfléchie revient, après traversée des déphaseurs, vers la face d'entrée de la lentille et une partie au moins de cette énergie se réfléchit à nouveau; elle retraverse les déphaseurs vers la face de sortie où, en partie au moins, elle sort de la lentille pour former un rayonnement parasite dont l'angle d'incidence n'est plus l'angle initial mais un angle qui lui est supérieur. Par ailleurs, la partie de l'énergie qui n'est pas sortie est à nouveau réfléchie comme décrit ci-dessus et donne naissance à un nouveau faisceau parasite émergeant, à angle d'incidence encore plus élevé, etc... Lorsqu'on mesure le diagramme de rayonnement d'une telle antenne, on voit ainsi apparaître des lobes secondaires dûs aux réflexions multiples. Ce phénomène augmente en intensité avec la valeur de l'angle d'incidence.When the angle of incidence becomes large, parasitic reflections of the microwave appear on the exit face of the lens. This reflected wave returns, after crossing the phase shifters, to the entry face of the lens and at least part of this energy is reflected again; it crosses the phase shifters towards the outlet face where, at least in part, it leaves the lens to form a stray radiation whose angle of incidence is no longer the initial angle but an angle which is greater than it. Furthermore, the part of the energy which has not left is again reflected as described above and gives rise to a new parasitic beam emerging at an even higher angle of incidence, etc ... When we measure the radiation pattern of such an antenna, we thus see the appearance of secondary lobes due to multiple reflections. This phenomenon increases in intensity with the value of the angle of incidence.

La présente invention a pour objet un dispositif destiné à l'absorption de ces réflexions multiples au niveau de la face d'entrée de la lentille, dispositif qui soit spatialement sélectif afin de n'absorber que les réflexions multiples et de ne pas perturber l'onde utile.The present invention relates to a device intended for the absorption of these multiple reflections at the level of the entry face of the lens, device which is spatially selective in order to absorb only the multiple reflections and not to disturb the useful wave.

Plus précisément, l'invention a pour objet un dispositif d'aborsption pour lentille hyperfréquence tel que défini dans la revendication 1.More specifically, the subject of the invention is an absorption device for a microwave lens as defined in claim 1.

D'autres objets, particularités et résultats de l'invention ressortiront de la description suivante, donnée à titre d'exemple non limitatif et illustrée par les figures annexées qui représentent:

  • la figure 1, le schéma d'une lentille hyperfréquence selon le brevet précité;
  • la figure 2, le schéma d'un panneau déphaseur utilisé dans le dispositif de la figure précédente;
  • la figure 3, un premier mode de réalisation de l'invention;
  • la figure 4, un deuxième mode de réalisation de l'invention;
  • la figure 5, un troisième mode de réalisation de l'invention;
  • la figure 6, un exemple d'application du dispositif selon l'invention.
Other objects, features and results of the invention will emerge from the following description, given by way of nonlimiting example and illustrated by the appended figures which represent:
  • Figure 1, the diagram of a microwave lens according to the aforementioned patent;
  • Figure 2, the diagram of a phase shift panel used in the device of the previous figure;
  • Figure 3, a first embodiment of the invention;
  • Figure 4, a second embodiment of the invention;
  • Figure 5, a third embodiment of the invention;
  • Figure 6, an example of application of the device according to the invention.

Sur ces différentes figures, les mêmes références se rapportent aux mêmes éléments.In these different figures, the same references relate to the same elements.

Par ailleurs, l'ensemble des explications qui sont données ci-après le sont, pour simplifier, en supposant que l'antenne fonctionne à l'émission, étant entendu que le fonctionnement en réception est symétrique.Furthermore, all the explanations given below are, for the sake of simplicity, assuming that the antenna operates on transmission, it being understood that the operation in reception is symmetrical.

La figure 1 représente donc schématiquement la lentille hyperfréquence décrite dans le brevet précité.FIG. 1 therefore schematically represents the microwave lens described in the aforementioned patent.

Cette lentille reçoit une énergie incidente illustrée par une flèche 10, se propageant selon une direction OZ et dont le champ électrique est dirigé selon un axe OY, normal au précédent. La lentille est constituée par une pluralité de déphaseurs D, empilés selon l'axe OY et séparés par des plans conducteurs C, qui s'étendent sensiblement perpendiculairement à l'axe OY; l'espace compris entre deux plans C est appelé ci-après indifféremment déphaseur ou canal. Chacun des déphaseurs imprime à l'onde hyperfréquence qui le traverse un déphasage dont la valeur est électriquement commandable. L'onde émergeant de la lentille, illustrée par une flèche 11, fait alors dans le plan YOZ un angle ϑ, dit angle d'incidence, avec sa direction initiale OZ; la valeur de l'angle ϑ est, ainsi qu'il est connu, fonction de la valeur des déphasages introduits par chacun des déphaseurs. On a encore illustré sur la figure 1, par des traits pointillés, la face d'entrée FE de la lentille, située du côté de l'énergie incidente 10, et la face de sortie FS, située du côté de l'onde émergente 11.This lens receives an incident energy illustrated by an arrow 10, propagating in a direction OZ and whose electric field is directed along an axis OY, normal to the previous one. The lens consists of a plurality of phase shifters D, stacked along the axis OY and separated by conductive planes C, which extend substantially perpendicular to the axis OY; the space between two planes C is hereinafter called either phase shifter or channel. Each of the phase shifters prints a phase shift whose value is electrically controllable to the microwave wave which passes through it. The wave emerging from the lens, illustrated by an arrow 11, then makes in the plane YOZ an angle ϑ, said angle of incidence, with its initial direction OZ; the value of the angle ϑ is, as is known, a function of the value of the phase shifts introduced by each of the phase shifters. There is also illustrated in FIG. 1, by dotted lines, the entry face F E of the lens, located on the side of the incident energy 10, and the exit face F S , located on the side of the wave. emerging 11.

Chacun des déphaseurs D est constitué par un ensemble de panneaux P, disposés parallèlement les uns aux autres et perpendiculairement à la direction OZ de propagation de l'énergie.Each of the phase shifters D is constituted by a set of panels P, arranged parallel to each other and perpendicular to the direction OZ of energy propagation.

La figure 2 est le schéma d'un mode de réalisation d'un panneau déphaseur P utilisé dans la lentille de la figure 1.FIG. 2 is the diagram of an embodiment of a phase shift panel P used in the lens of FIG. 1.

Ce panneau P comporte un substrat isolant 20 s'étendant dans un plan XOY perpendiculaire à la direction OZ. Sur le substrat 20 sont disposés des fils FD portant chacun un certain nombre de diodes D, par exemple deux sur la figure. Les fils à diodes FD sont disposés parallèlement à la direction du champ électrique de l'onde incidente, c'est-à-dire à l'axe OY. La tension de polarisation des diodes D est amenée aux diodes du panneau P par deux fils de commande FC′ connectant l'ensemble des fils à diodes FD et disposés parallèlement à l'axe OX. Les fils FC et FD sont de préférence réalisés sous forme de conducteurs imprimés sur le substrat 20.This panel P comprises an insulating substrate 20 extending in a plane XOY perpendicular to the direction OZ. On the substrate 20 are arranged wires F D each carrying a certain number of diodes D, for example two in the figure. The diode wires F D are arranged parallel to the direction of the electric field of the incident wave, that is to say to the axis OY. The bias voltage of the diodes D is brought to the diodes of the panel P by two control wires F C ′ connecting all of the diode wires F D and arranged parallel to the axis OX. The wires F C and F D are preferably produced in the form of conductors printed on the substrate 20.

La commande de l'état passant ou bloqué de l'ensemble des diodes D d'un panneau permet de faire varier le déphasage subi par l'onde traversant ce panneau.The control of the on or off state of all the diodes D of a panel makes it possible to vary the phase shift undergone by the wave passing through this panel.

Il apparaît ainsi qu'en disposant une pluralité de panneaux P selon l'axe OZ et en les commandant indépendamment les uns des autres, on constitue un déphaseur D dont le nombre de valeurs distinctes de déphasages possibles dépend du nombre de panneaux.It thus appears that by arranging a plurality of panels P along the axis OZ and controlling them independently of one another, a phase shifter D is formed, the number of distinct values of possible phase shifts depends on the number of panels.

La figure 3 représente un premier mode de réalisation du dispositif selon l'invention.FIG. 3 represents a first embodiment of the device according to the invention.

Sur cette figure, on a représenté un plan conducteur C s'étendant selon le plan XOZ, constitué par exemple par une plaque métallique. On a illustré par des traits pointillés les traces, parallèlement à l'axe OX, des panneaux déphaseurs P.In this figure, there is shown a conducting plane C extending along the plane XOZ, constituted for example by a metal plate. The traces, parallel to the axis OX, of the phase-shifting panels P have been illustrated by dashed lines.

Selon l'invention, il est réalisé dans chacun des plans conducteurs C une discontinuité électrique F, sous la forme d'une fente s'étendant selon l'axe OX entre la face d'entrée FE de la lentille, à une distance d de celle-ci, et le premier des panneaux déphaseurs P. Entre les deux bords de la fente F, de largeur e, sont électriquement connectées des résistances R, disposées à un pas p.According to the invention, an electrical discontinuity F is produced in each of the conducting planes C, in the form of a slot extending along the axis OX between the entry face F E of the lens, at a distance d thereof, and the first of the phase shift panels P. Between the two edges of the slot F, of width e , are electrically connected resistors R, arranged at a pitch p.

Le fonctionnement de ce dispositif est le suivant.The operation of this device is as follows.

Lorsque les ondes qui parcourent les canaux situés de part et d'autre du plan conducteur C sont en phase, les plans conducteurs C ne jouent aucun rôle. En effet, les ondes qui se propagent dans les canaux adjacents à un plan conducteur C donné induisent dans ce dernier des courants qui, lorsque les ondes sont en phase, s'annulent réciproquement; de la sorte, la fente et ses résistances n'ont aucun effet sur l'énergie se propageant dans les canaux. Cette situation est celle de l'énergie incidente (flèche 10 sur la figure 1), qui n'est ainsi pas perturbée par la présence du dispositif selon l'invention.When the waves which pass through the channels located on either side of the conducting plane C are in phase, the conducting planes C play no role. In fact, the waves which propagate in the channels adjacent to a given conducting plane C induce in the latter currents which, when the waves are in phase, cancel each other out; in this way, the slit and its resistances have no effect on the energy propagating in the channels. This situation is that of the incident energy (arrow 10 in FIG. 1), which is thus not disturbed by the presence of the device according to the invention.

Lorsque, au contraire, les ondes présentes dans les canaux adjacents sont des ondes parasites issues de réflexions multiples comme exposé plus haut, elles ont traversé au moins deux fois les panneaux déphaseurs et présentent alors, d'un canal à l'autre, un déphasage relatif. Les courants créés par ces ondes dans les plans conducteurs ne s'annulent plus jusqu'à s'ajouter lorsque le déphasage atteint 180°. Selon l'invention, ces courants sont alors absorbés par les résistances R, la géométrie de l'ensemble, c'est-à-dire la distance (d) de la fente F à la face d'entrée FE, le pas (p) des résistances, et la largeur (e) de la fente, notamment, ainsi que la valeur des résistances, étant optimisées pour que l'absorption soit maximale pour les valeurs usuelles de déphasage des ondes parasites. Les valeurs des différents paramètres peuvent être obtenues par le calcul, en se plaçant dans le cas où les ondes se propageant dans deux canaux adjacents sont en opposition de phase et en écrivant classiquement le circuit équivalent du dispositif et en ajoutant le fait qu'il n'y a pas de réflexions, c'est-à-dire que le circuit est adapté et que son impédance est égale à celle de l'onde, et/ou expérimentalement.When, on the contrary, the waves present in the adjacent channels are parasitic waves resulting from multiple reflections as explained above, they have passed through the phase-shift panels at least twice and then exhibit, from one channel to the other, a phase shift relative. The currents created by these waves in the conducting planes no longer cancel each other out until added when the phase shift reaches 180 °. According to the invention, these currents are then absorbed by the resistors R, the geometry of the assembly, that is to say the distance (d) from the slot F to the input face F E , the pitch ( p) resistors, and the width (e) of the slit, in particular, as well as the value of the resistors, being optimized so that the absorption is maximum for the usual values of phase shift of the parasitic waves. The values of the different parameters can be obtained by calculation, taking place in the case where the waves propagating in two adjacent channels are in phase opposition and by classically writing the equivalent circuit of the device and adding the fact that there n there are no reflections, that is to say that the circuit is adapted and that its impedance is equal to that of the wave, and / or experimentally.

A titre d'exemple, il a été élaboré un dispositif selon l'invention avec les valeurs suivantes: une distance d de l'ordre du quart de la longueur d'onde de l'onde traversant la lentille, ou un multiple de celui-ci; un pas p inférieur à une demi-longueur d'onde et une épaisseur e de l'ordre du dixième de longueur d'onde.By way of example, a device according to the invention has been developed with the following values: a distance d of the order of a quarter of the wavelength of the wave passing through the lens, or a multiple thereof. this; a pitch p less than half a wavelength and a thickness e of the order of a tenth of a wavelength.

La figure 4 représente schématiquement un deuxième mode de réalisation du dispositif selon l'invention.FIG. 4 schematically represents a second embodiment of the device according to the invention.

Sur cette figure, on a représenté un fragment d'un plan conducteur C. Celui-ci est réalisé par un dépôt conducteur 41 sur les deux faces d'un substrat isolant 40, par exemple du type de ceux qui sont utilisés pour réaliser les cartes de circuits imprimés. La discontinuité électrique F, ou fente, dans le plan conducteur est constituée ici par une absence de dépôt conducteur, sur les deux faces du substrat 40.In this figure, there is shown a fragment of a conductive plane C. This is produced by a conductive deposit 41 on both sides of an insulating substrate 40, for example of the type used to make the cards of printed circuits. The electrical discontinuity F, or slot, in the conductive plane is constituted here by an absence of conductive deposit, on the two faces of the substrate 40.

Les résistances R de la figure 3 sont, dans ce mode de réalisation, réalisées à l'aide de composants discrets 42, déposés sur les deux faces du substrat isolant 40 et connectés de part et d'autre aux dépôts métalliques 41, comme illustré pour la face supérieure sur la figure.The resistors R of FIG. 3 are, in this embodiment, produced using discrete components 42, deposited on the two faces of the insulating substrate 40 and connected on either side to the metal deposits 41, as illustrated for the upper side in the figure.

Bien entendu, la détermination des paramètres du dispositif d'absorption selon l'invention tient compte du fait que le dispositif comporte ici deux séries de résistances et non plus une seule, comme dans le cas de la figure 3. En première approximation, cela peut se traduire pour le circuit équivalent par la présence de deux résistances en parallèle au lieu d'une seule.Of course, the determination of the parameters of the absorption device according to the invention takes account of the fact that the device here comprises two series of resistances and no longer just one, as in the case of FIG. 3. As a first approximation, this may translate for the equivalent circuit by the presence of two resistors in parallel instead of one.

La figure 5 représente un troisième mode de réalisation du dispositif selon l'invention.FIG. 5 represents a third embodiment of the device according to the invention.

Sur cette figure, on retrouve comme sur la figure précédente le plan conducteur C réalisé à l'aide d'un substrat isolant 40 sur lequel sont déposées deux couches conductrices 41, sauf sur la zone destinée à former la discontinuité électrique, ou fente, F.In this figure, we find as in the previous figure the conductive plane C produced using an insulating substrate 40 on which are deposited two conductive layers 41, except on the area intended to form the electrical discontinuity, or slot, F .

Ce mode de réalisation diffère du précédent en ce que les résistances R de la figure 3 sont ici réalisées par un dépôt continu, sur chacune des faces du plan C, d'un matériau électriquement résistif 52 sur le substrat 40, au niveau de la fente F et débordant de part et d'autre sur la couche conductrice 41. Ce matériau 52 peut être par exemple une encre sérigraphiée telle que celles qui sont utilisées pour la réalisation de résistances dans la technique des circuits hybrides.This embodiment differs from the previous one in that the resistors R of FIG. 3 are here produced by a continuous deposition, on each of the faces of the plane C, of an electrically resistive material 52 on the substrate 40, at the level of the slot F and overflowing on both sides on the conductive layer 41. This material 52 may for example be a screen-printed ink such as those which are used for the production of resistors in the technique of hybrid circuits.

La figure 6 représente schématiquement un exemple d'application du dispositif selon l'invention.FIG. 6 schematically represents an example of application of the device according to the invention.

Sur cette figure, on désigne par L₂ une lentille hyperfréquence telle que décrite figures 1 et 2 ci-dessus. On a également schématisé ses plans conducteurs, repérés ici C2′ disposés parallèlement au plan XOZ et délimitant les canaux de la lentille. On a enfin illustré par un rectangle 60 en pointillés la fente et les résistances réalisées dans chacun des plans conducteurs C₂ du côté de la face d'entrée FE2 de la lentille L₂; il est à noter que les plans conducteurs C disposés aux extrémités de l'empilement formant la lentille ne nécessitent pas de dispositif absorbant 60.In this figure, L₂ designates a microwave lens as described in Figures 1 and 2 above. We have also schematically shown its conductive planes, identified here C 2 ′ arranged parallel to the plane XOZ and delimiting the channels of the lens. Finally, a slot 60 and a dotted rectangle have illustrated the slot and the resistances produced in each of the conductive planes C₂ on the side of the input face F E2 of the lens L₂; it should be noted that the conducting planes C arranged at the ends of the stack forming the lens do not require an absorbent device 60.

Dans cet exemple d'application, la lentille L₂ ne reçoit pas l'énergie qui est directement issue d'une source hyperfréquence mais une énergie ayant déjà subi une déflexion dans le plan XOZ à l'aide d'une première lentille L₁, analogue à la lentille L₂ mais dont les plans conducteurs s'étendent selon le plan YOZ. La lentille L₁ est avantageusement munie également d'un dispositif d'absorption selon l'invention (non visible sur la figure). Les deux lentilles sont séparées par une grille de rotation de polarisation GR′ destinée à faire tourner la polarisation de l'onde émergeant de la lentille L₁ de 90°, afin que celle-ci soit perpendiculaire aux plans conducteurs C₂. Dans cet exemple, la lentille L₂ est en outre suivie d'une grille de commutation de polarisation GC′ qui ou bien transmet l'onde qu'elle reçoit sans modification de sa polarisation, ou bien fait subir une rotation à la polarisation de l'onde.In this application example, the lens L₂ does not receive the energy which comes directly from a microwave source but an energy which has already undergone a deflection in the XOZ plane using a first lens L₁, analogous to the lens L₂ but whose conductive planes extend along the YOZ plane. The lens L₁ is advantageously also provided with an absorption device according to the invention (not visible in the figure). The two lenses are separated by a polarization rotation grid G R ′ intended to rotate the polarization of the wave emerging from the lens L₁ by 90 °, so that it is perpendicular to the conducting planes C₂. In this example, the lens L₂ is further followed by a polarization switching grid G C ′ which either transmits the wave which it receives without modifying its polarization, or alternatively rotates the polarization of l 'wave.

Dans une variante de réalisation, la lentille L₁ comporte en outre des moyens intégrés de génération d'une onde hyperfréquence dans chaque canal; dans ce cas le dispositif d'absorption selon l'invention est disposé entre les moyens de génération et les panneaux déphaseurs.In an alternative embodiment, the lens L₁ further comprises integrated means for generating a microwave wave in each channel; in this case the absorption device according to the invention is disposed between the generation means and the phase shift panels.

On a ainsi décrit un dispositif permettant d'absorber des ondes hyperfréquences dans les résistances R et, ce, d'une façon sélective, qu'on qualifie de spatialement sélective du fait que seules les ondes formant des rayonnements de grand angle d'incidence sont absorbées.We have thus described a device making it possible to absorb microwave waves in the resistors R and, this, in a selective manner, which is qualified as spatially selective because only the waves forming radiations of large angle of incidence are absorbed.

Claims (6)

Dispositif d'absorption d'ondes électromagnétiques dans une lentille hyperfréquence, la lentille comportant un empilement de déphaseurs (D) selon une première direction (OY), les déphaseurs étant séparés par des plans conducteurs (C) disposés sensiblement perpendiculairement à la première direction, chaque déphaseur comportant un empilement de panneaux déphaseurs (P) selon une deuxième direction (OZ), sensiblement normale à la première direction, le dispositif étant caractérisé par le fait qu'il comporte une discontinuité électrique (F) réalisée dans chacun des plans conducteurs disposés entre deux déphaseurs, et des moyens (R) électriquement résistifs, reliant les deux bords de la discontinuité, celle-ci étant disposée selon une troisième direction (OX), sensiblement normale aux première et deuxième directions, entre une face dite face d'entrée (FE) de la lentille qui reçoit l'onde électromagnétique et les premiers des panneaux déphaseurs.Device for absorbing electromagnetic waves in a microwave lens, the lens comprising a stack of phase shifters (D) in a first direction (OY), the phase shifters being separated by conducting planes (C) arranged substantially perpendicular to the first direction, each phase shifter comprising a stack of phase shifter panels (P) in a second direction (OZ), substantially normal to the first direction, the device being characterized in that it comprises an electrical discontinuity (F) produced in each of the conductive planes arranged between two phase shifters, and electrically resistive means (R), connecting the two edges of the discontinuity, the discontinuity being arranged in a third direction (OX), substantially normal to the first and second directions, between a face called the entry face (F E ) of the lens which receives the electromagnetic wave and the first of the phase shift panels. Dispositif selon la revendication 1, caractérisé par le fait que chacun des plans conducteurs (C) est formé par une plaque métallique dans laquelle est formée une fente constituant la discontinuité (F).Device according to claim 1, characterized in that each of the conductive planes (C) is formed by a metal plate in which is formed a slot constituting the discontinuity (F). Dispositif selon la revendication 1, caractérisé par le fait que chacun des plans conducteurs (C) est formé par un substrat isolant (40) sur chacune des faces duquel est déposée une couche conductrice (41) sauf au niveau de la discontinuité (F).Device according to claim 1, characterized in that each of the conductive planes (C) is formed by an insulating substrate (40) on each of the faces of which a conductive layer (41) is deposited except at the discontinuity (F). Dispositif selon l'une des revendications précédentes, caractérisé par le fait que les moyens résistifs (R) comportent des résistances discrètes (42), connectées entre les deux bords de la discontinuité.Device according to one of the preceding claims, characterized in that the resistive means (R) comprise discrete resistors (42), connected between the two edges of the discontinuity. Dispositif selon la revendication 3, caractérisé par le fait que les moyens résistifs (R) comportent une couche résistive (52) déposée sur chacune des faces du substrat isolant au niveau de la discontinuité (F) et en contact avec la couche conductrice (41).Device according to claim 3, characterized in that the resistive means (R) comprise a resistive layer (52) deposited on each of the faces of the insulating substrate at the discontinuity (F) and in contact with the conductive layer (41) . Antenne hyperfréquence, caractérisé par le fait qu'elle comporte une source hyperfréquence illuminant la lentille munie du dispositif selon l'une des revendications précédentes.Microwave antenna, characterized in that it comprises a microwave source illuminating the lens provided with the device according to one of the preceding claims.
EP90403443A 1989-12-05 1990-12-04 Device for spatially selective absorption of electro-magnetic waves for an ultra-high frequency lens Withdrawn EP0432034A1 (en)

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FR8916031A FR2655482B1 (en) 1989-12-05 1989-12-05 ELECTROMAGNETIC WAVE ABSORPTION DEVICE, SPATIALLY SELECTIVE, FOR MICROWAVE ANTENNA.
FR8916031 1989-12-05

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