EP0097073B1 - Procédé et dispositif de réduction de la puissance de signaux de brouillage reçus par les lobes latéraux d'une antenne radar - Google Patents

Procédé et dispositif de réduction de la puissance de signaux de brouillage reçus par les lobes latéraux d'une antenne radar Download PDF

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Publication number
EP0097073B1
EP0097073B1 EP83401063A EP83401063A EP0097073B1 EP 0097073 B1 EP0097073 B1 EP 0097073B1 EP 83401063 A EP83401063 A EP 83401063A EP 83401063 A EP83401063 A EP 83401063A EP 0097073 B1 EP0097073 B1 EP 0097073B1
Authority
EP
European Patent Office
Prior art keywords
auxiliary
diagrams
antenna
forming
diagram
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83401063A
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German (de)
English (en)
French (fr)
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EP0097073A1 (fr
Inventor
Serge Drabowitch
Claude Aubry
Daniel Casseau
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Thales SA
Original Assignee
Thomson CSF SA
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Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0097073A1 publication Critical patent/EP0097073A1/fr
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Expired legal-status Critical Current

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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
    • H01Q3/2629—Combination of a main antenna unit with an auxiliary antenna unit
    • H01Q3/2635—Combination of a main antenna unit with an auxiliary antenna unit the auxiliary unit being composed of a plurality of antennas

Definitions

  • the present invention relates to the protection of a radar system against jamming. It relates more particularly to a method and devices for reducing the power of the interference signals received by the side lobes of a radar antenna.
  • interference signals are generally active, natural or artificial, continuous or decoupled interference signals, sometimes emitted by several independent interferers and which are interfered with by internal noise from the associated receivers.
  • these interference signals are received by the secondary lobes of the radar antenna with a level such that they considerably reduce the signal to noise ratio and completely disrupt the operation of the radar.
  • auxiliary antennas with their reception channels, whose diagrams are combined with that of the main antenna considered so as to obtain a global diagram having zeros, or at least minima, in the directions of the external jammers while avoiding excessive amplification of the internal noises of the receivers associated with the auxiliary antennas.
  • Figure 1 recalls the classic diagram of a multi-jamming OLS system, comprising a number of decorrelation loops.
  • a conventional OLS system is a "looped" system mainly comprising a main antenna 1 and auxiliary antennas 2, 3 each associated with a reception channel 200, 300.
  • Each of these reception channels comprises a loop constituted by an amplifier 4, 40 , an integrator 5, 50, a correlator 6, 60 and a control mixer 7, 70.
  • each signal b, b 'received by an auxiliary antenna is cut off in a circuit 8 at signal b o received by the main antenna, after each auxiliary signal (b, b ') has been multiplied by a weighting coefficient (W, W') subject to the correlation existing between the auxiliary signal and the signal used.
  • the signal processed takes the form bo-bW-b'W. We show that the total noise is then minimum. The adaptation to the environment mentioned above is thus carried out.
  • Non-looped systems are also known, in which the optimal weighting coefficients W are determined by a calculation which amounts to inverting the covariance matrix of the signals received by the main antenna and the auxiliary signals.
  • auxiliary antennas are not indifferent to the speed of convergence of the process, to the final improvement factor, to the signal to interferer ratio, to the bandwidth of the system and the vulnerability of the system to additional interferers.
  • the object of the invention is both a method and a device for reducing the power of the interference signals received by the side lobes of a radar antenna which overcome the drawbacks mentioned above, and as defined respectively by claims 1 and 3.
  • limiters in different correlation loops, increasing the speed of convergence of said loops.
  • the main and auxiliary antennas must present diagrams such that the set of antennas constitutes a sort of spatial filter of the environment of the antenna,
  • an antenna structure can be defined, the optimized auxiliary diagrams of which have the characteristics which have been given.
  • Such diagrams are so-called sampling diagrams, produced from a linear network.
  • FIG. 2a schematically presents a linear network 9 of length L, identified by an abscissa x and which is the seat of an illumination IL, defined by the scalar complex function f (x) bounded by the domain (-U2, + L / 2).
  • This network radiates, in a direction 8 identified with respect to the normal N to the network 9, a diagram F ( ⁇ ) well represented, in FIG. 2b, by the Fourier transform of f (x), that is to say with: At being the wavelength.
  • Each sampling diagram has the characteristics which are those required according to the invention for an auxiliary diagram.
  • each sampling diagram in number N
  • N the subject of a separate entry
  • Such a multibeam antenna is shown in FIG. 4a very schematically.
  • the supply channels all include a weighting device 11, assigning to the signal which passes through them a weighting coefficient (Wi) determined in known manner; these paths are connected to a summing device 8, which also receives the main channel and feeding a receiver 12 which outputs the head signal of the interferers, or at least a signal in the equel the effect of interference is greatly attenuated.
  • a weighting device 11 assigning to the signal which passes through them a weighting coefficient (Wi) determined in known manner; these paths are connected to a summing device 8, which also receives the main channel and feeding a receiver 12 which outputs the head signal of the interferers, or at least a signal in the equel the effect of interference is greatly attenuated.
  • FIG. 4b shows the diagrams of the different elementary antennas 1 to N which play the role of the sampling diagrams defined above.
  • FIG. 5 schematically represents a multibeam antenna whose elementary digraphs meet the characteristics which have been defined previously and which is advantageously used to reduce the power of the jammers picked up by the antenna.
  • the network antenna 9 is supplied by a power divider 13 through phase shifters 14, creating the main channel.
  • the auxiliary channels are created from couplers 15, placed in front of the phase shifters 14, which derive part of the incident energy towards a Buttler matrix 10 whose other terminals are connected to weighters 11 connected to an adder 8 receiving the channel main VP.
  • the adder is connected to a receiver 12.
  • a network antenna powered by a lens preferably aplanatic.
  • the primary sources 17 illuminating the lens 16 generate, in a domain surrounding the main channel 18, the auxiliary directional diagrams 19 sought.
  • the weighted addition, in phase and in amplitude, of the signals received by the auxiliary diagram 19, receiving a jammer B, with the signals, received by the main diagram 18 makes it possible to obtain resulting signals in which the jammer is attenuated.
  • FIG. 7 represents such a primary source which allows better use of the antenna in the context of the invention.
  • the two antenna systems described above are particularly effective against multiple jammers located in directions not too far from that of the main lobe, a distance which can be measured in a few widths at 3 dB. If these jammers are distributed in a "horizontal" plane around the useful lobe, which is frequent in the case of distant powerful jammers, the sources are distributed as shown in figure 7.
  • array antenna can also be used, in accordance with the invention, to reduce the power of the jammers.
  • These are the network antennas supplied by a candlestick or espalier divider, that is to say a distributor circuit with successive divisions, produced with various technologies such as coaxial waveguides, triplates, printed circuits ...
  • the main channel is constituted by the main excitation input, or input of the sum channel "S" which produces a symmetrical, equiphase, attenuated illumination on the shaped edges. bell.
  • the main channel by location of imperfect control, along the network, of the phase and the amplitude in the frequency band to be covered, is accompanied by diffuse side lobes capable of collecting parasitic signals due to outdoor jammers.
  • the elementary couplers normally existing in the candlestick divider are replaced by directional couplers or of the magic tee type or of the hybrid ring type. All the elementary couplers are not systematically replaced but a certain number of them.
  • FIG. 8 represents, in a very schematic form, the linear network 9 of length L supplied by a candlestick so that one can distinguish there four sub-networks 20, 21, 22, 23 distributed symmetrically and supplied with the same power and equiphase by couplers 25, 26, 27 and 28, for example magic T's.
  • the central coupler 25 determines a sum channel S giving the main diagram and a difference channel D giving a difference diagram to constitute an auxiliary diagram within the meaning of the invention.
  • the couplers 26 and 27 each have a difference channel which are associated by lines of the same length with a coupler 28, magic tee or hybrid ring, which, developing the sum and the difference of the signals it receives, defines two other auxiliary diagrams , corresponding to what has been called, in an earlier publication of the applicant, the gap path (E) and the double difference path (D '). If we represent by a, b, c, and d respectively the amplitudes of the signals created by the networks 20-23, the difference path E is characterized by a diagram ((ab) + (cd)) and the double difference path From par ((ab) - (cd) 1.
  • FIG. 9 represents the laws of illumination of the different channels which have been defined from the array antenna of FIG. 8.
  • FIG. 14 schematically represents the device thus produced.
  • the network antenna 9 determines the main channel VP and the auxiliary channels 200, 300, 400 ... which are all connected to the summing circuit 8.
  • a limiter 29 In the correlation loop shown in FIG. 14 is inserted a limiter 29 before the correlator 6, through which the signal b, coming from the auxiliary antenna, passes. This is done for each correlation loop.

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  • Radar Systems Or Details Thereof (AREA)
  • Variable-Direction Aerials And Aerial Arrays (AREA)
EP83401063A 1982-05-27 1983-05-26 Procédé et dispositif de réduction de la puissance de signaux de brouillage reçus par les lobes latéraux d'une antenne radar Expired EP0097073B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8209257A FR2527785A1 (fr) 1982-05-27 1982-05-27 Procede et dispositif de reduction de la puissance des signaux de brouillage recus par les lobes lateraux d'une antenne radar
FR8209257 1982-05-27

Publications (2)

Publication Number Publication Date
EP0097073A1 EP0097073A1 (fr) 1983-12-28
EP0097073B1 true EP0097073B1 (fr) 1989-01-04

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EP83401063A Expired EP0097073B1 (fr) 1982-05-27 1983-05-26 Procédé et dispositif de réduction de la puissance de signaux de brouillage reçus par les lobes latéraux d'une antenne radar

Country Status (5)

Country Link
US (1) US4672378A (enExample)
EP (1) EP0097073B1 (enExample)
CA (1) CA1219324A (enExample)
DE (1) DE3378873D1 (enExample)
FR (1) FR2527785A1 (enExample)

Cited By (1)

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RU2302061C1 (ru) * 2006-02-15 2007-06-27 Михаил Борисович Мануилов Способ формирования многолепестковых диаграмм направленности антенной решетки

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RU2302061C1 (ru) * 2006-02-15 2007-06-27 Михаил Борисович Мануилов Способ формирования многолепестковых диаграмм направленности антенной решетки

Also Published As

Publication number Publication date
US4672378A (en) 1987-06-09
FR2527785A1 (fr) 1983-12-02
EP0097073A1 (fr) 1983-12-28
CA1219324A (en) 1987-03-17
DE3378873D1 (en) 1989-02-09
FR2527785B1 (enExample) 1985-01-18

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