EP0035439B1 - Method and antijamming device for a radar with an antenna for electronic scanning, and radar comprising such a device - Google Patents

Method and antijamming device for a radar with an antenna for electronic scanning, and radar comprising such a device Download PDF

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Publication number
EP0035439B1
EP0035439B1 EP81400286A EP81400286A EP0035439B1 EP 0035439 B1 EP0035439 B1 EP 0035439B1 EP 81400286 A EP81400286 A EP 81400286A EP 81400286 A EP81400286 A EP 81400286A EP 0035439 B1 EP0035439 B1 EP 0035439B1
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Prior art keywords
antenna
phase
plane
jamming
dephasers
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EP81400286A
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German (de)
French (fr)
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EP0035439A1 (en
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Robert Guilhem
Guy Leterrier
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • 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
    • H01Q3/2605—Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
    • H01Q3/2611—Means for null steering; Adaptive interference nulling
    • H01Q3/2617—Array of identical elements

Definitions

  • the invention relates to a method and an anti-jamming device for radar associated with an electronic scanning antenna; it also relates to a radar comprising such a device.
  • Modern aircraft are generally fitted with jamming devices which emit modulated waves in the frequency range of radars capable of detecting their presence.
  • the radars receiving the high power waves thus emitted by the jamming devices are saturated and made almost blind; this remains true even if the wave emitted by the jamming device only arrives in the direction of a secondary lobe of the radiation pattern of the radar antenna, taking into account the high level of power emitted by the jammer.
  • the devices of the prior art use auxiliary antennas responsible for receiving the signals transmitted by these jammers; the number of these antennas must be at least equal to that of the interference sources.
  • certain types of antenna with electronic deflection achieve the deflection of the beam by controlling the phase shifters connected to the elementary sources placed for example in a plane a phase value ⁇ ij defined by where i and j are whole numbers defining the position of the source considered with respect to two orthogonal directions OX and OY of the plane of the antenna, A ⁇ p x and A ⁇ py are the phase differences between two consecutive sources according to the OX and OY directions defining the phase plane perpendicular to the pointing direction, ⁇ ij is a constant phase shift independent of the pointing direction.
  • the electronic deflection of the beam is obtained by imposing on each elementary source of index i, j a phase shift ⁇ ij such that all the elementary sources radiate in phase in the chosen direction, taking into account their position in space and their feeding phase; this constitutes a wave surface perpendicular to the chosen direction.
  • the present invention aims to ensure anti-jamming by the use of a single electronic scanning antenna, the law of illumination of which is modified in phase and / or in amplitude by acting on the attenuator phase shifters connected to certain elementary sources, so that in the supposed direction of an interference source the gain of the antenna is zero or very low.
  • One of the characteristics of the invention consists in implementing means which add corrective terms to the value ⁇ ij defined above.
  • the anti-jamming method consists in modifying for each given interference source certain attenuator phase shifters associated with the elementary sources (which constitute the electronic scanning antenna) so that at the linear phase law corresponding to the desired direction of pointing of the antenna, or superimposed a disturbance law approaching a periodic law whose period measured in the plane of the antenna (or the opening thereof) parallel to the plane defined by the direction of the jammer and the normal to the antenna (or to its opening), law whose spatial period (wavelength) is given by where ⁇ is the wavelength used by the radar and 0 is the angle between the direction of the jammer and the normal defined above.
  • one modifies the amplitude of the law of disturbance and its position for performing its position a translation parallel to the direction in which is measured the LON g wave ueur these modifications being made so as to obtain a minimization of the gain of the antenna in the direction of the jamming device considered.
  • Another characteristic of the invention consists in modifying, for each interference source, certain phase shifters and / or attenuators associated with the elementary sources so that the disturbance law defined above is such that the disturbances considered alone have a radiation diagram having a maximum substantially in the direction of the interference source considered and a value as low as possible in the other directions, obtaining. of this latter characteristic being facilitated by the simultaneous use of phase and amplitude disturbances which makes it possible to greatly reduce the value of the radiation pattern in the direction symmetrical to that of the interference source considered with respect to the normal defined above. above.
  • Another characteristic of the invention consists in subjecting the phase disturbance law and / or in amplitude a translation such that it modifies the phase of the radiation pattern of the disturbances considered alone so as to minimize the overall radiation pattern of the antenna in the direction of the interference source considered by substantially opposing the radiation pattern. radiation from disturbances to that of the undisturbed antenna, this for the direction of the interference source considered.
  • ⁇ x bn and ⁇ y bn are the phase differences between two consecutive sources (in the directions OX and OY) defining by their value a phase plane perpendicular to the direction of the n th interference device b n ,
  • a n and ⁇ n are two adjustable phase parameters whose value is controlled by a computer
  • a double disturbance in amplitude and in phase corresponding to the combination of two previously defined disturbances is produced on the antenna.
  • the method according to the invention consists in playing on certain phase-attenuators associated with the elementary sources constituting the electronic scanning antenna.
  • Figure la shows the phase laws applied to the phase shifters of the electronic scanning antenna.
  • the electronic scanning antenna 1 is assumed to be in a plane (OX, OY); OZ represents the normal to this plane with respect to 0, point of intersection of the plane of antenna 1 with the axis of symmetry of this antenna OB ; represents the direction of the interference source of rank i, 0 the angle (OZ, OB ; ) and OP the pointing direction of the electronic scanning antenna 1.
  • the plane 2 represents an equiphase plane passing through 0 and corresponding to pointing direction OP.
  • Curve 3 represents an example of a supposed sinusoidal phase modulation law which is superimposed on the straight line 2. It therefore assumes a suitable algebraic variation of the phase angles of certain phase-shifters according to a distribution law on the surface of the approximately sinusoidal antenna.
  • A represents the amplitude of this phase modulation law.
  • the direction OBi of the jamming device of rank i is a priori arbitrary. Consequently the cancellation or the minimization of the gain in the direction of the jamming device actually requires two quasi-periodic disturbances of the phase law, according to the two directions OX and OY and that the resulting law of disturbance of wavelength spatial ⁇ / sin ⁇ is defined parallel to the intersection of the antenna plane and the plane (OZ, OB i ); to obtain this disturbance law, perturbations are carried out parallel to the axis OX and to the axis OY which correspond to the terms ⁇ x bn and ⁇ y bn .
  • phase shifters are quantified and controlled by binary words. Therefore curves 2 and 3 of the figure characterizing it respectively the linear phase law defining the pointing direction OP and the phase modulation law, close to a sinusoid, allowing the decrease in gain in the direction OB ; , can only be approached.
  • Figure 1b shows an example of the approximation of these curves.
  • N be the number of phase shifters located in a volume limited by two planes perpendicular to the line of intersection of the plane of the antenna and the plane (OY, OB i ) and distant by a deviation, from, weak compared to the period
  • the modification of the values of the phase shift angles of these n phase shifters by the same quantity ⁇ A n risks giving too great a contribution with respect to the gain of the antenna in the direction OB i which one seeks to minimize.
  • the perturbation law will not be applied to phase shifters having a quantization error less than a value given for the phase law defining the pointing direction OP of the antenna.
  • FIG. 2 gives an example of a device implementing the method described above.
  • the device comprises a radar deviation receiver 66 receiving the signals from the electronic scanning antenna via a terminal 65.
  • This radar deviation receiver 66 is connected to a computer 110 and to a set of N identical phase-shifter control circuits 40, each of them being connected to a phase-shifter-attenuator of an elementary source by means of a terminal 30.
  • a single phase-shifter control circuit 40 is shown so to facilitate understanding.
  • the computer 110 is connected to the N phase-shifting control circuits 40, and to a comparison circuit 50 making it possible to compare, for the same pointing direction of the electronic scanning antenna, the different values of the sum signal ⁇ coming from the deviation meter receiver radar 66 for different settings of the phase shifters attenuators associated with the elementary sources constituting the radar antenna.
  • the comparison circuit 50 comprises a controlled switch 62 receiving the sum signal ⁇ from the radar deviation receiver 66 and connected at output to a comparator 64 and to a memory 63; the control of this switch 62 is connected to the computer 110 and to a set of logic AND circuits 32 via a counting circuit 31.
  • This set of circuits Logical AND 32 is connected to the computer 110, to a comparator 64 and to a memory 63, this memory 63 also being connected to the comparator 64.
  • Each control circuit 40 comprises two memory pairs 9, 10 and 7, 8 each couple being connected to an addition circuit 18 by means of a controlled switch 16, 23 and a multiplication circuit 17, 22 receiving the output of a memory 12,13.
  • Each of the memories 7, 8, 9, 10 is connected to the radar deviation receiver 66.
  • the addition circuit 18 is connected to two memories 14 and 15 by means of a controlled switch 19.
  • the output of the addition circuit 18 is connected to a controlled switch 20; a first output of this controlled switch 20 is connected to a multiplication circuit 25 via a circuit 21 calculating the function cos x, x being the signal applied to its input.
  • the multiplication circuit 25 also receives the content of a memory 26 and the content of memories 24 via a circuit 200 calculating the cosine of the values from the memories 24. Its output is connected to an addition circuit 28 via memories 29.
  • the second output of the controlled switch 20 is also connected to this addition circuit 28 via the memory circuits 24.
  • the output of the addition circuit 28 is connected to a terminal 30 connected to the phase shifter-attenuator of the elementary source on which this control circuit 40 will act, by means of a circuit 27 rounding the number from the addition circuit 28.
  • the two sets of memories 15 and 26 are directly controlled by the computer 110.
  • the above circuits are of the logic type with the exception of the radar deviation receiver.
  • the following description of the operation is made by assuming all of the circuits making up the comparison circuit 50 and the control circuits 40 produced with logic circuits.
  • the radar deviation receiver 66 identifies the directions of the different sources of interference. Each of these directions is identified by a phase plane perpendicular to the direction of the jamming device.
  • Knowledge of OB management ; of a particular jammer determines the phase differences ⁇ b x and ⁇ b y between two phase shifters-attenuators associated with two consecutive elementary sources in the directions OX and OY of the antenna. These pairs of values ( ⁇ ⁇ b x , ⁇ b y ) are stored in a memory internal to the radar deviation receiver 66 during a first antenna scan. This information is renewed every r antenna scans.
  • Any pointing direction of the electronic scanning antenna is also defined by a phase shift torque ⁇ x , A ⁇ py.
  • the values ⁇ x and A ⁇ py are transmitted respectively to two memories 8 and 100, the values ⁇ bn x and ⁇ bn y , associated with the n th scrambling device, respectively to memories 7 and 9.
  • the computer 110 receives from the radar deviation meter receiver 66 the value of the gain of the electronic scanning antenna in the direction of the interference source considered with respect to the pointing direction, thus allowing the computer 110 to estimate the number and the distribution of phase-attenuators associated with the elementary sources which it will modify.
  • the computer 110 then positions all of the controlled switches 16, 23, 19 and 20 of each control circuit 40 associated with a phase shifter-attenuator of an elementary source in the position shown in FIG. 2. This position of the switches is called by the following position 1, the different position being called position 2. Similarly, this computer transmits to memories 12 and 13, by links not described in FIG. 2, the values i and j corresponding to the number j of the column parallel to OX in which is the phase shift considered and rank i in this column. This operation is therefore equivalent to matrixing the electronic scanning antenna in the directions OX and OY defined by the direction of the jamming device.
  • phase shift term ⁇ ij associated with each phase shifter and which compensates for a possible phase shift originating for example from the position on the antenna, from the elementary source which is associated with it relative. to the microwave power supply of this antenna.
  • the addition circuit 28 then delivers a signal equivalent to: which has been stored in the set of memories 24 and which corresponds exclusively to the pointing of the electronic scanning antenna in the chosen direction. Then the computer 110 switches to position 2, the controlled switches 16, 19, 20 and 23 of certain control circuits 40, associated with the elementary sources. The addition circuit 28 then delivers the sum of the previous phase term contained in the memory 24 and the correction term contained in the memory 29 corresponding to the product of the cosine terms from the circuits 21 and 200, then factorized, with the amplitude A, in the multiplication circuit 25.
  • ⁇ ij the total phase applied to this phase shifter for a given jammer: the y value being stored in a memory included in the circuit 200 calculates the cosine and where A and ⁇ are the values corresponding to the n th IEM jammer, respectively from memories 15 and 16.
  • a circuit 27 then operates the rounding of this number; in fact, the phase-shifting attenuators being generally controlled by binary words of K bits, the binary word representing ⁇ ij must be rounded up to the nearest binary word of K bits before being applied to the control of the phase shifter by means of terminal 30.
  • the values A and ⁇ being able to vary respectively from 0 to A n and from 0 to 2n by successive discrete values, the computer 110 repeats this operation of calculation of ⁇ ij for all the possible values of the couple (A, ⁇ ).
  • the computer 110 opens the switch 62 allowing the application of the value, previously sampled and coded in binary, of the sum signal ⁇ coming from the radar deviation receiver 66.
  • This opening of the controlled switch 62 also causes the incrementation of a unit of a counting circuit 31.
  • the value of the sum signal ⁇ is compared using a comparator 64 to the previous value of this same signal sum ⁇ associated with the previous pair (A, ⁇ ) and stored in a memory 63. If the sum signal E applied to comparator 64 is smaller than the previous signal stored in memory 63, comparator 64 delivers a signal which firstly causes the smallest sum sum somme to be stored in memory 63, and secondly authorizes the transfer to the computer 110 of the binary number existing on the outputs of the counting circuit 31 via a set of logic AND circuits 32.
  • the computer 110 receives from the counting circuit 31 the number of the couple (A, ⁇ ) corresponding to a minimum value of the sum signal ⁇ . The computer 110 then puts in the memories 15 and 26 the corresponding values of A and ⁇ .
  • the computer repeats these operations for the n interference sources Bi acting on different control circuits 40 for each interference source.
  • phase disturbance and / or amplitude law applied to the phase shifter-attenuators of the elementary antennas must be such that, measured in the phase plane of the pointing of the antenna, this is periodic.

Description

L'invention concerne un procédé et un dispositif d'antibrouillage pour radar associé à une antenne à balayage électronique; elle concerne également un radar comprenant un tel dispositif.The invention relates to a method and an anti-jamming device for radar associated with an electronic scanning antenna; it also relates to a radar comprising such a device.

Les avions modernes sont généralement pourvus de dispositifs de brouillage qui émettent des ondes modulées dans le domaine de fréquence des radars susceptibles de détecter leur présence. Les radars recevant les ondes de forte puissance ainsi émises par les dispositifs de brouillage sont saturés et rendus quasiment aveugles; ceci reste vrai même si l'onde émise par le dispositif de brouillage n'arrive que dans la direction d'un lobe secondaire du diagramme de rayonnement de l'antenne radar, compte tenu du haut niveau de puissance émise par le brouilleur.Modern aircraft are generally fitted with jamming devices which emit modulated waves in the frequency range of radars capable of detecting their presence. The radars receiving the high power waves thus emitted by the jamming devices are saturated and made almost blind; this remains true even if the wave emitted by the jamming device only arrives in the direction of a secondary lobe of the radiation pattern of the radar antenna, taking into account the high level of power emitted by the jammer.

Pour remédier à cet inconvénient, les dispositifs de l'art antérieur utilisent des antennes auxiliaires chargées de recevoir les signaux émis par ces brouilleurs; le nombre de ces antennes doit être au moins égal à celui des sources de brouillage.To overcome this drawback, the devices of the prior art use auxiliary antennas responsible for receiving the signals transmitted by these jammers; the number of these antennas must be at least equal to that of the interference sources.

Les signaux issus de ces antennes auxiliaires sont ajoutés aux signaux de l'antenne principale après traitement en phase et en amplitude de telle sorte que la somme totale présente une énergie de brouillage nulle ou du moins fortement atténuée. Cette solution toutefois présente des inconvénients: l'un d'entre eux est directement lié au nombre d'antenne auxiliaires à utiliser. Ces inconvénients font que la mise en oeuvre pratique d'un tel dispositif d'antibrouillage est délicate.The signals from these auxiliary antennas are added to the signals of the main antenna after processing in phase and in amplitude so that the total sum has zero or at least strongly attenuated interference energy. This solution however has drawbacks: one of them is directly linked to the number of auxiliary antennas to be used. These drawbacks make the practical implementation of such an anti-jamming device difficult.

Selon l'art antérieur, certains types d'antennes à déflexion électronique réalisent la déflexion du faisceau en commandant aux déphaseurs reliés aux sources élémentaires placées par exemple dans un plan une valeur de phase ϕij définie par

Figure imgb0001
où i et j sont des nombres entiers définissant la position de la source considérée par rapport à deux directions orthogonales OX et OY du plan de l'antenne, A<px et A<py sont les écarts de phase entre deux sources consécutives selon les directions OX et OY définissant le plan de phase perpendiculaire à la direction de pointage, ψij est un déphasage constant indépendant de la direction de pointage.According to the prior art, certain types of antenna with electronic deflection achieve the deflection of the beam by controlling the phase shifters connected to the elementary sources placed for example in a plane a phase value ϕ ij defined by
Figure imgb0001
 where i and j are whole numbers defining the position of the source considered with respect to two orthogonal directions OX and OY of the plane of the antenna, A <p x and A <py are the phase differences between two consecutive sources according to the OX and OY directions defining the phase plane perpendicular to the pointing direction, ψ ij is a constant phase shift independent of the pointing direction.

Selon l'art antérieur, d'une façon plus générale, la déflexion électronique du faisceau est obtenue en imposant à chaque source élémentaire d'indice i, j un déphasage ϕij tel que toutes les sources élémentaires rayonnent en phase dans la direction choisie, compte tenu de leur position dans l'espace et de leur phase d'alimentation; on constitue ainsi une surface d'onde perpendiculaire à la direction choisie.According to the prior art, more generally, the electronic deflection of the beam is obtained by imposing on each elementary source of index i, j a phase shift ϕ ij such that all the elementary sources radiate in phase in the chosen direction, taking into account their position in space and their feeding phase; this constitutes a wave surface perpendicular to the chosen direction.

D'autre part, il est connu, comme décrit dans le brevet US-A-4189 733 d'utiliser un système de modulation/démodulation effectuant une expansion et compression du signal afin de réduire l'amplitude des signaux provenant des directions différentes de la direction du pointage de l'antenne. De même il est connu, comme décrit dans la demande publiée EP-A-014 650, de placer devant une antenne radar un filtre constitué par des fils parallèles parcourus par des courants électriques, afin d'atténuer des lobes secondaires du diagrame de rayonnement de ladite antenne.On the other hand, it is known, as described in US Pat. No. 4,189,733, to use a modulation / demodulation system performing signal expansion and compression in order to reduce the amplitude of the signals coming from directions different from the pointing direction of the antenna. Likewise, it is known, as described in published application EP-A-014 650, to place in front of a radar antenna a filter constituted by parallel wires traversed by electric currents, in order to attenuate secondary lobes of the radiation diagram of said antenna.

La présente invention vise à assurer l'antibrouillage par l'utilisation d'une unique antenne à balayage électronique dont on modifie la loi d'illumination en phase et/ou en amplitude en agissant sur les déphaseurs atténuateurs reliés à certaines sources élémentaires, afin que dans la direction supposée d'une source de brouillage le gain de l'antenne soit nul ou très faible.The present invention aims to ensure anti-jamming by the use of a single electronic scanning antenna, the law of illumination of which is modified in phase and / or in amplitude by acting on the attenuator phase shifters connected to certain elementary sources, so that in the supposed direction of an interference source the gain of the antenna is zero or very low.

Une des caractéristiques de l'invention consiste à mettre en oeuvre des moyens qui ajoutent des termes correctifs à la valeur ϕij définie ci-dessus.One of the characteristics of the invention consists in implementing means which add corrective terms to the value ϕ ij defined above.

Selon l'invention, le procédé d'antibrouillage consiste à modifier pour chaque source de brouillage donnée certains déphaseurs atténuateurs associés aux sources élémentaires (qui constituent l'antenne à balayage électronique) de telle façon qu'à la loi linéaire de phase correspondant à la direction désirée du pointage de l'antenne, soit superposée une loi de perturbation se rapprochant d'une loi périodique dont la période mesurée dans le plan de l'antenne (ou de l'ouverture de celle-ci) parallèlement au plan défini par la direction du brouilleur et la normale à l'antenne (ou à son ouverture), loi dont la période spatiale (longueur d'onde) est donnée par

Figure imgb0002
où À est la longueur d'onde utilisée par le radar et 0 l'angle entre la direction du brouilleur et la normale définie ci-dessus. Selon une autre caractéristique de ce procédé, on modifie l'amplitude de la loi de perturbation et sa position en effectuant pour sa position une translation parallèle à la direction selon laquelle est mesurée la lon- gueur d'onde
Figure imgb0003
 ces modifications étant faites de manière à obtenir une minimisation du gain de l'antenne dans la direction du dispositif de brouillage considéré.According to the invention, the anti-jamming method consists in modifying for each given interference source certain attenuator phase shifters associated with the elementary sources (which constitute the electronic scanning antenna) so that at the linear phase law corresponding to the desired direction of pointing of the antenna, or superimposed a disturbance law approaching a periodic law whose period measured in the plane of the antenna (or the opening thereof) parallel to the plane defined by the direction of the jammer and the normal to the antenna (or to its opening), law whose spatial period (wavelength) is given by
Figure imgb0002
 where À is the wavelength used by the radar and 0 is the angle between the direction of the jammer and the normal defined above. According to another feature of this method, one modifies the amplitude of the law of disturbance and its position for performing its position a translation parallel to the direction in which is measured the LON g wave ueur
Figure imgb0003
 these modifications being made so as to obtain a minimization of the gain of the antenna in the direction of the jamming device considered.

Une autre caractéristique de l'invention consiste à modifier pour chaque source de brouillage certains déphaseurs et/ou atténuateurs associés aux sources élémentaires de telle façon que la loi de perturbation définie plus haut soit telle que les perturbations considérées seules aient un diagramme de rayonnement possédant un maximum sensiblement dans la direction de la source de brouillage considérée et une valeur aussi faible que possible dans les autres directions, l'obtention. de cette dernière caractéristique étant facilitée par l'emploi simultané de perturbations de phase et d'amplitude qui permet de diminuer fortement la valeur du diagramme de rayonnement dans la direction symétrique de celle de la source de brouillage considérée par rapport à la normale définie ci-dessus.Another characteristic of the invention consists in modifying, for each interference source, certain phase shifters and / or attenuators associated with the elementary sources so that the disturbance law defined above is such that the disturbances considered alone have a radiation diagram having a maximum substantially in the direction of the interference source considered and a value as low as possible in the other directions, obtaining. of this latter characteristic being facilitated by the simultaneous use of phase and amplitude disturbances which makes it possible to greatly reduce the value of the radiation pattern in the direction symmetrical to that of the interference source considered with respect to the normal defined above. above.

Une autre caractéristique de l'invention consiste à faire subir à la loi de perturbation en phase et/ou en amplitude une translation telle qu'elle modifie la phase du diagramme de rayonnement des perturbations considérées seules de manière à minimiser le diagramme de rayonnement global de l'antenne dans la direction de la source de brouillage considérée en opposant sensiblement le diagramme de rayonnement des perturbations à celui de l'antenne non perturbée, ceci pour la direction de la source de brouillage considérée.Another characteristic of the invention consists in subjecting the phase disturbance law and / or in amplitude a translation such that it modifies the phase of the radiation pattern of the disturbances considered alone so as to minimize the overall radiation pattern of the antenna in the direction of the interference source considered by substantially opposing the radiation pattern. radiation from disturbances to that of the undisturbed antenna, this for the direction of the interference source considered.

Selon une caractéristique de l'invention, les moyens mettant en oeuvre ce procédé, dans le cas d'une antenne plane, comportent un ensemble de N dispositifs de commande associés aux N déphaseurs-atténuateurs des sources élémentaires composant l'antenne, chacun de ces dispositifs étant connecté à un calculateur et au récepteur d'écartométrie radar, P dispositifs de commande parmi ces N délivrant aux déphaseurs auxquels ils sont associés une valeur de phase ϕij définie par

Figure imgb0004
avec y = 0 ou π/2 où i et j (comme plus haut) sont des nombres entiers définissant la position de la source élémentaire associée par rapport à deux directions orthogonales OX et OY du plan de l'antenne, Δϕx et Δϕy sont, conformément à l'art antérieur, les écarts de phase entre deux sources consécutives (selon les directions OX et OY) définissant par leur valeur le plan de phase perpendiculaire à la direction de pointage, ψij est un terme constant indépendant du pointage dû à la position géographique sur l'antenne du déphaseur considéré, mais où, selon l'invention le terme correctif
Figure imgb0005
est défini comme suit:According to a characteristic of the invention, the means implementing this method, in the case of a planar antenna, comprise a set of N control devices associated with the N phase-shifter-attenuators of the elementary sources making up the antenna, each of these devices being connected to a computer and to the radar deviation meter receiver, P control devices among these N delivering to the phase shifters with which they are associated a phase value ϕ ij defined by
Figure imgb0004
 with y = 0 or π / 2 where i and j (as above) are whole numbers defining the position of the associated elementary source with respect to two orthogonal directions OX and OY of the plane of the antenna, Δϕ x and Δϕ y are, in accordance with the prior art, the phase differences between two consecutive sources (along the directions OX and OY) defining by their value the phase plane perpendicular to the pointing direction, ψ ij is a constant term independent of the pointing due at the geographic position on the antenna of the phase shifter considered, but where, according to the invention, the term corrective
Figure imgb0005
 is defined as follows:

Δϕx bn et Δϕy bn sont les écarts de phase entre deux sources consécutives (selon les directions OX et OY) définissant par leur valeur un plan de phase perpendiculaire à la direction du nième dispositif de brouillage bn,Δϕ x bn and Δϕ y bn are the phase differences between two consecutive sources (in the directions OX and OY) defining by their value a phase plane perpendicular to the direction of the n th interference device b n ,

An et Øn sont deux paramètres de phase réglables dont la valeur est commandée par un calculateur,A n and Ø n are two adjustable phase parameters whose value is controlled by a computer,

le terme cos (jΔϕx+iΔϕy) provient de la nécessité d'appliquer une perturbation quasi périodique, l'élaboration de la perturbation devant prendre en compte les valeurs algébriques des phases principales appliquées aux sources élémentaires afin d'obtenir un pointage du lobe principal de rayonnement de l'antenne dans une direction donnée.the term cos (jΔϕ x + iΔϕ y ) comes from the need to apply an almost periodic perturbation, the development of the perturbation having to take into account the algebraic values of the main phases applied to elementary sources in order to obtain a pointing of the lobe main antenna radiation in a given direction.

Selon une autre caractéristique de l'invention, on réalise sur l'antenne une perturbation d'amplitude représentée par le terme général pour la source i,j:

Figure imgb0006
avec y' = 0 ou n/2 en choisissant de préférence Bn = ± An, Ø'n=Øn+b (avec b = 0 ou π) les Cn étant tels que l'amplitude de la perturbation soit toujours négative pour chacun des brouilleurs supposé isolé.According to another characteristic of the invention, an amplitude disturbance is represented on the antenna represented by the general term for the source i, j:
Figure imgb0006
 with y '= 0 or n / 2 preferably choosing B n = ± A n , Ø'n = Øn + b (with b = 0 or π) the C n being such that the amplitude of the disturbance is always negative for each jammer assumed to be isolated.

Selon une autre caractéristique de l'invention, on réalise sur l'antenne une double perturbation en amplitude et en phase correspondant à la combinaison de deux perturbations précédemment définies.According to another characteristic of the invention, a double disturbance in amplitude and in phase corresponding to the combination of two previously defined disturbances is produced on the antenna.

D'autres avantages et caractéristiques de la présente invention ressortiront de la description qui suit, donnée à l'aide des figures qui représentent

  • - les figures 1a et 1b, un schéma montrant les lois de phase appliquées aux déphaseurs de l'antenne à balayage électronique;
  • - la figure 2, un bloc diagramme général montrant un exemple de réalisation du dispositif selon l'invention.
Other advantages and characteristics of the present invention will emerge from the description which follows, given with the aid of the figures which represent
  • - Figures 1a and 1b, a diagram showing the phase laws applied to the phase shifters of the electronic scanning antenna;
  • - Figure 2, a general block diagram showing an embodiment of the device according to the invention.

Comme il a été dit, le procédé suivant l'invention consiste à jouer sur certains déphaseurs-atténuateurs associés aux sources élémentaires constituant l'antenne à balayage électronique.As has been said, the method according to the invention consists in playing on certain phase-attenuators associated with the elementary sources constituting the electronic scanning antenna.

La figure la montre les lois de phase appliquées aux déphaseurs-atténuateurs de l'antenne à balayage électronique.Figure la shows the phase laws applied to the phase shifters of the electronic scanning antenna.

L'antenne à balayage électronique 1 est supposée dans un plan (OX, OY); OZ représente la normale à ce plan par rapport à 0, point d'intersection du plan de l'antenne 1 avec l'axe de symétrie de cette antenne OB; représente la direction de la source de brouillage de rang i, 0 l'angle (OZ, OB;) et OP la direction de pointage de l'antenne à balayage électronique 1. Le plan 2 représente un plan équiphase passant par 0 et correspondant à la direction de pointage OP.The electronic scanning antenna 1 is assumed to be in a plane (OX, OY); OZ represents the normal to this plane with respect to 0, point of intersection of the plane of antenna 1 with the axis of symmetry of this antenna OB ; represents the direction of the interference source of rank i, 0 the angle (OZ, OB ; ) and OP the pointing direction of the electronic scanning antenna 1. The plane 2 represents an equiphase plane passing through 0 and corresponding to pointing direction OP.

La courbe 3 représente un exemple de loi de modulation de phase supposée sinusoïdale qui est superposée à la droite équiphase 2. Elle suppose donc une variation algébrique convenable des angles de phase de certains déphaseurs-atténuateurs selon une loi de répartition sur la surface de l'antenne approximativement sinusoïdale. La projection de cette loi de perturbation périodique de phase sur la doirte formée par l'intersection du plan de l'antenne 1, et du plan formé par l'axe mécanique OZ de cette antenne et la direction OB; du brouilleur considéré, définit des longueurs AB et CD correspondant à une période de cette loi périodique de perturbation de phase appliquée aux déphaseurs de l'antenne; chacun de ces segments AB ou CD a pour longueur

Figure imgb0007
étant la longueur d'onde utilisée par le radar. A représente l'amplitude de cette loi de modulation de phase.Curve 3 represents an example of a supposed sinusoidal phase modulation law which is superimposed on the straight line 2. It therefore assumes a suitable algebraic variation of the phase angles of certain phase-shifters according to a distribution law on the surface of the approximately sinusoidal antenna. The projection of this law of periodic phase perturbation on the doirte formed by the intersection of the plane of the antenna 1, and of the plane formed by the mechanical axis OZ of this antenna and the direction OB ; of the jammer considered, defines lengths AB and CD corresponding to a period of this periodic law of phase disturbance applied to the phase shifters of the antenna; each of these segments AB or CD has the length
Figure imgb0007
 being the wavelength used by the radar. A represents the amplitude of this phase modulation law.

Les calculs et les expérimentations faits montrent, qu'une modification de l'angle de phase de certains déphaseurs, permettant d'obtenir cette loi de perturbation de phase périodique, entraîne notamment dans une direction donnée OB; une modification des lobes secondaires du diagramme de rayonnement de l'antenne à balayage électronique; de plus les expérimentations ont montré qu'il existe toujours une translation selon la direction du vecteur u parallèle au plan de la phase 2 de cette perturbation de phase permettant d'obtenir dans la direction du dispositif de brouillage Bi un minimum de gain de l'antenne, ce minimum pouvant dans certains cas être un zéro de gain.The calculations and the experiments made show that a modification of the phase angle of certain phase shifters, making it possible to obtain this periodic phase disturbance law, results in particular in a given direction OB ; a modification of the side lobes of the radiation pattern of the scanning antenna electronic; in addition, experiments have shown that there is always a translation along the direction of the vector u parallel to the plane of phase 2 of this phase perturbation, making it possible to obtain in the direction of the jamming device Bi a minimum gain of the antenna, this minimum can in some cases be zero gain.

Il faut noter que la direction OBi du dispositif de brouillage de rang i est a priori quelconque. Par conséquent l'annulation ou la minimisation du gain dans la direction du dispositif de brouillage nécessite en fait deux perturbations quasi-périodiques de la loi de phase, selon les deux directions OX et OY et que la loi de perturbation résultante de longueur d'onde spatiale λ/sinΘ est définie parallèlement à l'intersection du plan de l'antenne et du plan (OZ, OBi); pour obtenir cette loi de perturbation, on réalise des perturbations parallèles à l'axe OX et à l'axe OY qui correspondent aux termes Δϕx bn et Δϕy bn.It should be noted that the direction OBi of the jamming device of rank i is a priori arbitrary. Consequently the cancellation or the minimization of the gain in the direction of the jamming device actually requires two quasi-periodic disturbances of the phase law, according to the two directions OX and OY and that the resulting law of disturbance of wavelength spatial λ / sinΘ is defined parallel to the intersection of the antenna plane and the plane (OZ, OB i ); to obtain this disturbance law, perturbations are carried out parallel to the axis OX and to the axis OY which correspond to the terms Δϕ x bn and Δϕ y bn .

En pratique, les déphaseurs sont quantifiés et commandés par des mots binaires. De ce fait les courbes 2 et 3 de la figure la caractérisant respectivement la loi linéaire de phase définissant la direction de pointage OP et la loi de modulation de phase, proche d'une sinusoïde, permettant la diminution du gain dans la direction OB;, ne peuvent être qu'approchées.In practice, the phase shifters are quantified and controlled by binary words. Therefore curves 2 and 3 of the figure characterizing it respectively the linear phase law defining the pointing direction OP and the phase modulation law, close to a sinusoid, allowing the decrease in gain in the direction OB ; , can only be approached.

La figure 1b montre un exemple de l'approximation de ces courbes. Pour la loi de modulation périodique de phase représentée par la courbe 3 cela revient à un échantillonnage, et de ce fait les quantums 4 et 5 sont les quantums qui sont nécessaires au minimum pour définir une loi périodique. Soit N le nombre de déphaseurs se trouvant dans un volume limité par deux plans perpendiculaires à la droite d'intersection du plan de l'antenne et du plan (OY, OBi) et distant d'un écart, du, faible devant la période

Figure imgb0008
La modification des valeurs des angles de déphasage de ces n déphaseurs d'une même quantité ± An risque de donner une contribution trop importante par rapport au gain de l'antenne dans la direction OBi que l'on cherche à minimiser. On est donc conduit à limiter le choix à P déphaseurs (P ≼ N). Ils peuvent être, notamment, répartis uniformément dans une direction perpendiculaire à OX, ce qui revient à dire que, parmit les N déphaseurs, on modifie le réglage d'un déphaseur sur q, q étant le nombre défini par N = P.q.Figure 1b shows an example of the approximation of these curves. For the periodic phase modulation law represented by curve 3, this amounts to sampling, and therefore quantums 4 and 5 are the quantums which are necessary at least to define a periodic law. Let N be the number of phase shifters located in a volume limited by two planes perpendicular to the line of intersection of the plane of the antenna and the plane (OY, OB i ) and distant by a deviation, from, weak compared to the period
Figure imgb0008
 The modification of the values of the phase shift angles of these n phase shifters by the same quantity ± A n risks giving too great a contribution with respect to the gain of the antenna in the direction OB i which one seeks to minimize. We are therefore led to limit the choice to P phase shifters (P ≼ N). They can be, in particular, distributed uniformly in a direction perpendicular to OX, which amounts to saying that, among the N phase shifters, we modify the setting of a phase shifter on q, q being the number defined by N = Pq

Par exemple, la loi de perturbation ne sera pas appliquée aux déphaseurs ayant une erreur de quantification inférieure à une valeur donnée pour la loi de phase définissant la direction de pointage OP de l'antenne.For example, the perturbation law will not be applied to phase shifters having a quantization error less than a value given for the phase law defining the pointing direction OP of the antenna.

Le procédé selon l'invention permettant la réduction du gain de l'antenne à balayage électronique 1 dans une direction OB, d'un dispositif de brouillage comporte donc les étapes suivantes, la direction de pointage OP de l'antenne 1 étant fixe:

  • - détermination de la direction des brouilleurs;
  • - calcul de la période
    Figure imgb0009
     directement ou pro- jeté sur des axes déterminés;
  • - modification de l'angle de phase de certains déphaseurs de l'antenne pour donner une loi de perturbation de phase 3, approximativement sinusoïdale; le nombre de déphaseurs sur lequel on joue étant choisi en fonction du gain de l'antenne à minimiser dans la direction du dispositif de brouillage;
  • - translation de cette loi de perturbation de phase parallèlement à la droite d'intersection du plan de l'antenne et du plan (OZ, OBi) de façon à obtenir dans la direction OBi un gain minimal de l'antenne à balayage électronique 1;
  • - répétition de l'ensemble de ces opérations pour chaque direction OBi correspondant à une source de brouillage. Cette séquence d'opération est refaite à chaque nouvelle direction OP de pointage de l'antenne, car lorsque cette direction de pointage change, tout le diagramme de rayonnement de l'antenne se modifie et les minimisations précédentes ne sont plus valables.
The method according to the invention allowing the reduction of the gain of the electronic scanning antenna 1 in a direction OB, of a jamming device therefore comprises the following steps, the pointing direction OP of the antenna 1 being fixed:
  • - determination of the direction of the jammers;
  • - period calculation
    Figure imgb0009
     directly or projected on specific axes;
  • - modification of the phase angle of certain phase shifters of the antenna to give a phase 3 disturbance law, approximately sinusoidal; the number of phase shifters being played being chosen as a function of the gain of the antenna to be minimized in the direction of the jamming device;
  • - Translation of this phase perturbation law parallel to the line of intersection of the plane of the antenna and the plane (OZ, OB i ) so as to obtain in the direction OB i a minimum gain of the antenna with electronic scanning 1;
  • - repetition of all of these operations for each direction OB i corresponding to a source of interference. This sequence of operations is repeated with each new direction of pointing of the antenna, because when this direction of pointing changes, the whole radiation pattern of the antenna changes and the previous minimizations are no longer valid.

La figure 2 donne un exemple de dispositif mettant en oeuvre le procédé décrit précédemment.FIG. 2 gives an example of a device implementing the method described above.

Le dispositif comporte un récepteur d'écarto- métrie radar 66 recevant les signaux de l'antenne à balayage électronique par l'intermédiaire d'une borne 65. Ce récepteur d'écartométrie radar 66 est connecté à un calculateur 110 et à un ensemble de N circuits identiques de commande de déphaseurs 40, chacun d'eux étant relié à un déphaseur-atténuateur d'une source élémentaire par l'intermédiair d'une borne 30. Sur la figure 2 un seul circuit de commande de déphaseur 40 est représenté afin de faciliter la compréhension. Le calculateur 110 est connecté aux N circuits de commande de déphaseurs 40, et à un circuit de comparaison 50 permettant de comparer pour une même direction de pointage de l'antenne à balayage électronique les différentes valeurs du signal somme Σ issu du récepteur d'écartométrie radar 66 pour différents réglages des déphaseurs-atténuateurs associés aux sources élémentaires constituant l'antenne du radar.The device comprises a radar deviation receiver 66 receiving the signals from the electronic scanning antenna via a terminal 65. This radar deviation receiver 66 is connected to a computer 110 and to a set of N identical phase-shifter control circuits 40, each of them being connected to a phase-shifter-attenuator of an elementary source by means of a terminal 30. In FIG. 2, a single phase-shifter control circuit 40 is shown so to facilitate understanding. The computer 110 is connected to the N phase-shifting control circuits 40, and to a comparison circuit 50 making it possible to compare, for the same pointing direction of the electronic scanning antenna, the different values of the sum signal Σ coming from the deviation meter receiver radar 66 for different settings of the phase shifters attenuators associated with the elementary sources constituting the radar antenna.

Le circuit de comparaison 50 comporte un interrupteur commandé 62 recevant le signal somme Σ du récepteur d'écartométrie radar 66 et connecté en sortie à un comparateur 64 et à une mémoire 63; la commande de cet interruptuer 62 est reliée au calculateur 110 et à un ensemble de circuits ET logiques 32 par l'intermédiaire d'un circuit de comptage 31. Cet ensemble de circuits ET logiques 32 est relié au calculateur 110, à un comparateur 64 et à une mémoire 63, cette mémoire 63 étant également connectée au comparateur 64.The comparison circuit 50 comprises a controlled switch 62 receiving the sum signal Σ from the radar deviation receiver 66 and connected at output to a comparator 64 and to a memory 63; the control of this switch 62 is connected to the computer 110 and to a set of logic AND circuits 32 via a counting circuit 31. This set of circuits Logical AND 32 is connected to the computer 110, to a comparator 64 and to a memory 63, this memory 63 also being connected to the comparator 64.

Chaque circuit de commande 40 comporte deux couples de mémoire 9, 10 et 7, 8 chaque couple étant connecté à un circuit d'addition 18 par l'intermédiaire d'un interrupteur commandé 16, 23 et d'un circuit de multiplication 17, 22 recevant la sortie d'une mémoire 12,13. Chacune des mémoires 7, 8, 9, 10 est connectée au récepteur d'écarto- métrie radar 66. Le circuit d'addition 18 est connecté à deux mémoires 14 et 15 par l'intermédiaire d'un interrupteur commandé 19.Each control circuit 40 comprises two memory pairs 9, 10 and 7, 8 each couple being connected to an addition circuit 18 by means of a controlled switch 16, 23 and a multiplication circuit 17, 22 receiving the output of a memory 12,13. Each of the memories 7, 8, 9, 10 is connected to the radar deviation receiver 66. The addition circuit 18 is connected to two memories 14 and 15 by means of a controlled switch 19.

La sortie du circuit d'addition 18 est connectée à un interrupteur commandé 20; une première sortie de cet interrupteur commandé 20 est reliée à un circuit de multiplication 25 par l'intermédiaire d'un circuit 21 calculant la fonction cos x, x étant le signal appliqué à son entrée. Le circuit de multiplication 25 reçoit également le contenu d'une mémoire 26 et le contenu de mémoires 24 par l'intermédiaire d'un circuit 200 calculant le cosinus des valeurs issues des mémoires 24. Sa sortie est connectée à un circuit d'addition 28 par l'intermédiaire de mémoires 29. La seconde sortie de l'interrupteur commandé 20 est également reliée à ce circuit d'addition 28 par l'intermédiaire des circuits mémoires 24. La sortie du circuit d'addition 28 est connectée à une borne 30 reliée au déphaseur-atténuateur de la source élémentaire sur laquelle ce circuit de commande 40 va agir, par l'intermédiaire d'un circuit 27 effectuant l'arrondi du nombre issu du circuit d'addition 28. Les deux ensembles de mémoires 15 et 26 sont directement commandés par le calculateur 110.The output of the addition circuit 18 is connected to a controlled switch 20; a first output of this controlled switch 20 is connected to a multiplication circuit 25 via a circuit 21 calculating the function cos x, x being the signal applied to its input. The multiplication circuit 25 also receives the content of a memory 26 and the content of memories 24 via a circuit 200 calculating the cosine of the values from the memories 24. Its output is connected to an addition circuit 28 via memories 29. The second output of the controlled switch 20 is also connected to this addition circuit 28 via the memory circuits 24. The output of the addition circuit 28 is connected to a terminal 30 connected to the phase shifter-attenuator of the elementary source on which this control circuit 40 will act, by means of a circuit 27 rounding the number from the addition circuit 28. The two sets of memories 15 and 26 are directly controlled by the computer 110.

De façon préférentille, les circuits précédents sont du type logique à l'exception du récepteur d'écartométrie radar. La description du fonctionnement qui suit est faite en supposant l'ensemble des circuits composant le circuit de comparaison 50 et les circuits de commande 40 réalisés avec des circuits logiques.Preferably, the above circuits are of the logic type with the exception of the radar deviation receiver. The following description of the operation is made by assuming all of the circuits making up the comparison circuit 50 and the control circuits 40 produced with logic circuits.

Pendant un premier balayage d'antenne, le récepteur d'écartométrie radar 66 repère les directions des différentes sources de brouillage. Chacune de ces directions est repérée par un plan de phase perpendiculaire à la direction du dispositif de brouillage.During a first antenna scan, the radar deviation receiver 66 identifies the directions of the different sources of interference. Each of these directions is identified by a phase plane perpendicular to the direction of the jamming device.

La connaissance de la direction OB; d'un brouilleur particulier détermine les écarts de phase Δϕb x et Δϕb y entre deux déphaseurs-atténuateurs associés à deux sources élémentaires consécutives selon les directions OX et OY de l'antenne. Ces couples de valeurs (Δϕ b x, Δϕb y) sont mémorisés dans une mémoire interne au récepteur d'écartométrie radar 66 pendant un premier balayage d'antenne. Ces informations sont renouvelées tous les r balayages d'antenne.Knowledge of OB management ; of a particular jammer determines the phase differences Δϕ b x and Δϕ b y between two phase shifters-attenuators associated with two consecutive elementary sources in the directions OX and OY of the antenna. These pairs of values (Δ ϕ b x , Δϕ b y ) are stored in a memory internal to the radar deviation receiver 66 during a first antenna scan. This information is renewed every r antenna scans.

Une direction de pointage quelconque de l'antenne à balayage électronique est également défini par un couple de déphasage Δϕx, A<py.Any pointing direction of the electronic scanning antenna is also defined by a phase shift torque Δϕ x , A <py.

Pour cette direction de pointage les valeurs Δϕx et A<py sont transmises respectivement à deux mémoires 8 et 100, les valeurs Δϕbn x et Δϕbn y, associées au nième dispositif de brouillage, respectivement aux mémoires 7 et 9.For this pointing direction the values Δϕ x and A <py are transmitted respectively to two memories 8 and 100, the values Δϕ bn x and Δϕ bn y , associated with the n th scrambling device, respectively to memories 7 and 9.

Parallèlement le calculateur 110 reçoit du récepteur d'écartométrie radar 66 la valeur du gain de l'antenne à balayage électronique dans la direction de la source de brouillage considérée par rapport à la direction de pointage, permettant ainsi au calculateur 110 d'estimer le nombre et la répartition des déphaseurs-atténuateurs associés aux sources élémentaires qu'il va modifier.In parallel, the computer 110 receives from the radar deviation meter receiver 66 the value of the gain of the electronic scanning antenna in the direction of the interference source considered with respect to the pointing direction, thus allowing the computer 110 to estimate the number and the distribution of phase-attenuators associated with the elementary sources which it will modify.

Le calculateur 110 positionne ensuite tous les interrupteurs commandés 16, 23, 19 et 20 de chaque circuit de commande 40 associé à un déphaseur-atténuateur d'une source élémentaire sur la position représentée sur la figure 2. Cette position des interrupteurs est appelée par la suite position 1, la position différente étant appelée position 2. De même ce calculateur transmet aux mémoires 12 et 13, par des liaisons non décrites sur la figure 2, les valeurs i et j correspondant au numéro j de la colonne parallèle à OX dans laquelle se trouve le déphaseur considéré et le rang i dans cette colonne. Cette opération est donc équivalente à un matriçage de l'antenne à balayage électronique selon les directions OX et OY définies par la direction du dispositif de brouillage.The computer 110 then positions all of the controlled switches 16, 23, 19 and 20 of each control circuit 40 associated with a phase shifter-attenuator of an elementary source in the position shown in FIG. 2. This position of the switches is called by the following position 1, the different position being called position 2. Similarly, this computer transmits to memories 12 and 13, by links not described in FIG. 2, the values i and j corresponding to the number j of the column parallel to OX in which is the phase shift considered and rank i in this column. This operation is therefore equivalent to matrixing the electronic scanning antenna in the directions OX and OY defined by the direction of the jamming device.

Dans la mémoire 14 se trouve de façon permanente un terme de déphasage ψij associé à chaque déphaseur et qui compense un éventuel déphasage provenant par exemple de la position sur l'antenne, de la source élémentaire qui lui est associée par rapport. à l'alimentation hyperfréquence de cette antenne.In the memory 14 there is permanently a phase shift term ψ ij associated with each phase shifter and which compensates for a possible phase shift originating for example from the position on the antenna, from the elementary source which is associated with it relative. to the microwave power supply of this antenna.

Le positionnement des interrupteurs commandés étant effectué, le circuit d'addition 28 délivre alors un signal équivalent à:

Figure imgb0010
qui a été stocké dans l'ensemble de mémoires 24 et qui correspond exclusivment au pointage de l'antenne à balayage électronique dans la direction choisie. Puis le calculateur 110 bascule dans la position 2, les interrupteurs commandés 16, 19, 20 et 23 de certains circuits de commande 40, associés aux sources élémentaires. Le circuit d'addition 28 délivre alors la somme du terme de phase précédent contenu dans la mémoire 24 et du terme de correction contenu dans la mémoire 29 correspondant au produit des termes en cosinus issus des circuits 21 et 200, puis factorisés, avec l'amplitude A, dans le circuit de multiplication 25. Si l'on note ϕij la phase totale appliquée à ce déphaseur pour un brouilleur donné:
Figure imgb0011
la valeur de y étant stockée dans une mémoire incluse dans le circuit 200 calculant le cosinus et où A et Φ sont les valeurs correspondant au nièm e brouilleur, issues respectivement des mémoires 15 et 16. Un circuit 27 opère ensuite l'arrondi de ce nombre; en effet les déphaseurs-atténuateurs étant généralement commandés par des mots binaires de K bits, le mot binaire représentant ϕij doit être arrondi au mot binaire de K bits le plus proche avant d'être appliqué sur la commande du déphaseur par l'intermédiaire de la borne 30.The positioning of the controlled switches being carried out, the addition circuit 28 then delivers a signal equivalent to:
Figure imgb0010
 which has been stored in the set of memories 24 and which corresponds exclusively to the pointing of the electronic scanning antenna in the chosen direction. Then the computer 110 switches to position 2, the controlled switches 16, 19, 20 and 23 of certain control circuits 40, associated with the elementary sources. The addition circuit 28 then delivers the sum of the previous phase term contained in the memory 24 and the correction term contained in the memory 29 corresponding to the product of the cosine terms from the circuits 21 and 200, then factorized, with the amplitude A, in the multiplication circuit 25. If we denote by ϕ ij the total phase applied to this phase shifter for a given jammer:
Figure imgb0011
 the y value being stored in a memory included in the circuit 200 calculates the cosine and where A and Φ are the values corresponding to the n th IEM jammer, respectively from memories 15 and 16. A circuit 27 then operates the rounding of this number; in fact, the phase-shifting attenuators being generally controlled by binary words of K bits, the binary word representing ϕ ij must be rounded up to the nearest binary word of K bits before being applied to the control of the phase shifter by means of terminal 30.

Les valeurs A et Φ pouvant respectivement varier de 0 à An et de 0 à 2n par valeurs discrètes successives, le calculateur 110 repète cette opération de calcul de ϕij pour toutes les valeurs possibles du couple (A, Φ).The values A and Φ being able to vary respectively from 0 to A n and from 0 to 2n by successive discrete values, the computer 110 repeats this operation of calculation of ϕ ij for all the possible values of the couple (A, Φ).

Parallèlement, à chaque valeur du couple (A, Φ), le calculateur 110 ouvre l'interrupteur 62 permettant l'application de la valeur, préalablement échantillonnée et codée en binaire, du signal somme Σ issu du récepteur d'écartométrie radar 66.In parallel, at each value of the couple (A, Φ), the computer 110 opens the switch 62 allowing the application of the value, previously sampled and coded in binary, of the sum signal Σ coming from the radar deviation receiver 66.

Cette ouverture de l'interrupteur commandé 62 provoque également l'incrémentation d'une unité d'un circuit de comptage 31. La valeur du signal somme Σ est comparée à l'aide d'un comparateur 64 à la valeur précédente de ce même signal somme Σ associé au couple (A, Φ) précédent et stocké dans une mémoire 63. Si le signal somme E appliqué au comparateur 64 est plus petit que le signal précédent stocké dans la mémoire 63, le comparateur 64 délivre un signal qui d'une part provoque la mise en mémoire 63 du plus petit des signaux somme Σ, et d'autre part autorise le transfert au calculateur 110 du nombre binaire existant sur les sorties du circuit de comptage 31 par l'intermédiaire d'un ensemble de circuits ET logiques 32.This opening of the controlled switch 62 also causes the incrementation of a unit of a counting circuit 31. The value of the sum signal Σ is compared using a comparator 64 to the previous value of this same signal sum Σ associated with the previous pair (A, Φ) and stored in a memory 63. If the sum signal E applied to comparator 64 is smaller than the previous signal stored in memory 63, comparator 64 delivers a signal which firstly causes the smallest sum sum somme to be stored in memory 63, and secondly authorizes the transfer to the computer 110 of the binary number existing on the outputs of the counting circuit 31 via a set of logic AND circuits 32.

Lorsque l'ensemble des couples (A, Φ) a été essayé, le calculateur 110 reçoit du circuit de comptage 31 le numéro du couple (A, Φ) correspondant à une valeur minimale du signal somme Σ. Le calculateur 110 remet alors dans les mémoires 15 et 26 les valeurs de A et Φ correspondantes.When all the couples (A, Φ) have been tested, the computer 110 receives from the counting circuit 31 the number of the couple (A, Φ) corresponding to a minimum value of the sum signal Σ. The computer 110 then puts in the memories 15 and 26 the corresponding values of A and Φ.

On dispose ainsi d'une réduction maximale, dans cette direction de pointage de l'antenne, du bruit de la nième source de brouillage. Le calculateur renouvelle ces opérations pour les n sources de brouillage Bi agissant sur des circuits de commande 40 différents pour chaque source de brouillage.There is thus a maximum reduction, in this direction of pointing of the antenna, of the noise of the n th interference source. The computer repeats these operations for the n interference sources Bi acting on different control circuits 40 for each interference source.

A la fin de ces opérations formant une séquence, on dispose dans la direction de pointage choisie d'un signal reçu pour lequel le bruit des sources de brouillage est minimisé. Afin d'optimiser la réduction des brouilleurs, cette séquence est répétée plusieurs fois, ce qui permet de tenir compte des interactions faibles entre les minimisations.At the end of these operations forming a sequence, there is available in the chosen pointing direction a received signal for which the noise from the interference sources is minimized. In order to optimize the reduction of jammers, this sequence is repeated several times, which makes it possible to take account of the weak interactions between the minimizations.

Une variante de ce procédé de minimisation est obtenue par une loi de perturbation d'amplitude appliquée suivant la même séquence que précédemment décrit, la commande des déphaseurs étant remplacée par celle des atténuateurs, les mémoires 8 et 10 correspondant aux termes Δϕx et Δϕy étant alors inutiles.A variant of this minimization process is obtained by an amplitude perturbation law applied in the same sequence as previously described, the control of the phase shifters being replaced by that of the attenuators, the memories 8 and 10 corresponding to the terms Δϕ x and Δϕ y then being useless.

Dans le cas de l'utilisation d'une antenne non plane, la loi de perturbation de phase et/ou d'amplitude appliquée aux déphaseurs-atténuateurs des antennes élémentaires doit être telle que, mesurée dans le plan de phase du pointage de l'antenne, celle-ci soit périodique.In the case of the use of a non-planar antenna, the phase disturbance and / or amplitude law applied to the phase shifter-attenuators of the elementary antennas must be such that, measured in the phase plane of the pointing of the antenna, this is periodic.

On a ainsi décrit un procédé d'antibrouillage pour antenne à balayage électronique et un radar muni d'une antenne à balayage électronique utilisant ce procédé.An anti-jamming method for an electronic scanning antenna and a radar equipped with an electronic scanning antenna using this method have thus been described.

Claims (10)

1. Antijamming process for deviation measurement meter radar associated to an electronic scanning plane antenna (1) comprising, a network, having a symmetry center (o), elementary sources with their address dephaser-attenuator i, j with respect to two orthogonal directions OX and OY of the antenna plane, consisting in making a calculation intended for the determination of an equiphase plane Z corresponding to the target direction (OP) of the antenna, the said antenna emitting signals at wavelength λ and receiving in a direction 0 with respect to its axis of symmetry (OZ) the signals emitted by a jamming source (Bi), characterized in that the procedure occurs according to the following steps:
- an antenna scanning allowing the radar deviation measurement receiver (66) to log the directions of the different jamming sources (Bi);
- calculation of a periodic phase disturbance law (3) in the equiphase plane 2 corresponding to the target direction O P of the antenna of spatial period λ/sin Θ defined parallelwise to the plane intersection (λ) of the antenna and of the plane OZ, OBi and of which the equiphase points form in the plane of the antenna (1) lines that are approximately straight and parallel between them to the directions OX and OY;
- calculation and selection of the number of address dephasers-attentuators i, j and modification of the phase and/or the amplitude by these dephaser-attenuaters in order to obtain this disturbance law, determining a gain reduction of the antenna in the direction 0 of the jammer involved, for the target direction OP of the antenna.
2. Anti-jamming process according to claim 1, characterized in that the substantially periodic phase disturbance law (3) is close to a sinusoïd.
3. Anti-jamming process according to claim 2, characterized in that the quasi-sinusoidal disturbance law is represented by at least two samples corresponding approximatively to the maximum of this sinusoid, the amplitude of each sample representing an algebraic phase and/or amplitude modification of the address attenuators dephasers i,j of the antenna.
4. Anti-jamming process according to claim 1, characterized in that the disturbance law undergoes a translation in the phase plane (2) associated to the target direction (0 P) of the antenna, according to the direction of the vector u parallel to the equiphase plane (2) so as to obtain a minimum gain in the direction of the jamming source.
5. Anti-jamming process according to claim 1, characterized in that the number of dephasers-attenuators acting to generate the phase and/or amplitude disturbance law is proportional to the gain of the antenna in the direction 0 of the jamming device involved.
6. Anti-jamming process according to claim 5, characterized in that the dephasers-attenuators involved by the phase and/or amplitude disturbance law are uniformly distributed on the surface of the antenna.
7. Anti-jamming device using a plane electronic scanning antenna, comprising a network having a symmetry center (o), N elementary sources provided with their address dephaser-attenuator i, j with respect to two orthogonal directions OX and OY of the antenna plane for the implementation of the anti-jamming process according to claim 1, characterized in that it comprises an assembly of N control circuits (40) associated to N dephasers-attenuators of the elementary sources constituting the electronic scanning antenna, each of these N control circuits (40) being connected to a calculator (110) and to the radar deviation measurement receiver (66), P control circuits (40) among these N delivering to the dephasers to which they are associated a phase value ϕij defined by:
Figure imgb0015
where y = 0 or π/2 and where i and j are integers defining the position of the involved dephaser with respect to the two orthogonal directons OX andOY of the antenna plane, one of these directions being parallel to the orthogonal projection on this same antenna plane of the direction of the jamming source (Bi) that it is sought to eliminate, Δϕx and Δϕy the phase deviations between two consecutive dephasers-ateenuators along directions OX and OY allowing to define the equiphase plane (2) perpendicular to the target direction Δϕbn x and Δϕbn y the phase deviations between two consecutive dephasers along directions OX and OY allowing to define the phase plane perpendicular to the direction of the jamming source (Bi) of order n, An and Φn two adjustable phase parameters the value of which for each jammer is controlled by the calculator (110), the N-P control circuits (40) remaining, delivering to the dephasers-attenuators to which they are associated a phase value ϕ'i,j defined by
Figure imgb0016
where ψij is a constant term taking into account the dephasage due to the position of the dephaser-attenuator on the antenna.
8. Anti-jamming device according to claim 7, characterized in that it comprises a comparison circuit (50) connected to the calculator (110) and to the radar deviation measurement (66), this comparison circuit comparing the successive values of the summing-up signal Σ issuing from the radar deviation measurement receiver (66) associated to each couple of values A and transmitted by the calculator (110) to the control circuits (40) and only retaining the address of the couple of values (A, ϕ) giving the smallest value of the summing-up singal Σ.
9. Anti-jamming device according to claim 7, characterized in that each control circuit (40) comprises controlled ON/OFF switches in such a way that, remaining in the first position, the output signal of this control circuit (40) represents the phase ϕij and being successively put into the two positions, the output signal of this control circuit (40) represents the phase ϕij.
10. Anti-jamming device according to claim 7, characterized in that an amplitude disturbance law is applied on each dephaser-attenuator of rank i, j of the antenna (1) alone or in combination with the phase disturbance law applied to the dephasers-attenuators of this same antenna (1), this amplitude disturbance law being defined by
Figure imgb0017
 where Bn = ±An, Φ'n = Φn + b with b = 0 or π, and Cn a constant so that the amplitude of the disturbance is negative for each of the presumed isolated jammers and y' a constant equal to 0 or π/2.
EP81400286A 1980-03-04 1981-02-24 Method and antijamming device for a radar with an antenna for electronic scanning, and radar comprising such a device Expired EP0035439B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8004836 1980-03-04
FR8004836A FR2477784A1 (en) 1980-03-04 1980-03-04 METHOD AND DEVICE FOR RADAR ANTI-AGING ASSOCIATED WITH AN ELECTRONIC SCANNING ANTENNA AND RADAR COMPRISING SUCH A DEVICE

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EP0035439A1 EP0035439A1 (en) 1981-09-09
EP0035439B1 true EP0035439B1 (en) 1984-10-24

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EP (1) EP0035439B1 (en)
CA (1) CA1177565A (en)
DE (1) DE3166762D1 (en)
DK (1) DK94881A (en)
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NO (1) NO153072C (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3453623A (en) * 1966-07-06 1969-07-01 Technology Uk Phase-optimized antennae system
US3964065A (en) * 1974-12-17 1976-06-15 The United States Of America As Represented By The Secretary Of The Army Steerable antenna null combiner system
US4189733A (en) * 1978-12-08 1980-02-19 Northrop Corporation Adaptive electronically steerable phased array
EP0014650A1 (en) * 1979-02-05 1980-08-20 Societe D'etude Du Radant Microwave adaptive spatial filter and its method of use in lowering or suppressing the sidelobes of the radiation pattern of an antenna

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3670335A (en) * 1967-06-08 1972-06-13 Bell Telephone Labor Inc Arrays with nulls steered independently of main beam

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3453623A (en) * 1966-07-06 1969-07-01 Technology Uk Phase-optimized antennae system
US3964065A (en) * 1974-12-17 1976-06-15 The United States Of America As Represented By The Secretary Of The Army Steerable antenna null combiner system
US4189733A (en) * 1978-12-08 1980-02-19 Northrop Corporation Adaptive electronically steerable phased array
EP0014650A1 (en) * 1979-02-05 1980-08-20 Societe D'etude Du Radant Microwave adaptive spatial filter and its method of use in lowering or suppressing the sidelobes of the radiation pattern of an antenna

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EP0035439A1 (en) 1981-09-09
NO810731L (en) 1981-09-07
NO153072B (en) 1985-09-30
DE3166762D1 (en) 1984-11-29
CA1177565A (en) 1984-11-06
FR2477784B1 (en) 1983-12-23
FR2477784A1 (en) 1981-09-11
NO153072C (en) 1986-01-08
DK94881A (en) 1981-09-05

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