EP0275303B1 - Appareil d'antenne a reseau a dephasage a semi-conducteurs a faible rayonnement des lobes laterals - Google Patents

Appareil d'antenne a reseau a dephasage a semi-conducteurs a faible rayonnement des lobes laterals Download PDF

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Publication number
EP0275303B1
EP0275303B1 EP19870905342 EP87905342A EP0275303B1 EP 0275303 B1 EP0275303 B1 EP 0275303B1 EP 19870905342 EP19870905342 EP 19870905342 EP 87905342 A EP87905342 A EP 87905342A EP 0275303 B1 EP0275303 B1 EP 0275303B1
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Prior art keywords
power modules
groups
zone
gain
sidelobe
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EP19870905342
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German (de)
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EP0275303A1 (fr
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Jar Jueh Lee
Raymond Tang
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Raytheon Co
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Hughes Aircraft Co
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
    • H01Q21/22—Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/0006—Particular feeding systems
    • H01Q21/0025—Modular arrays

Definitions

  • the present invention relates generally to a solid state, phased array antenna according to the preamble of claim 1.
  • Radar antennas are well known to radiate microwave radiation in a broad pattern which, for directed antenna, includes a narrow mainlobe and wide sidelobes of radiation.
  • the mainlobe is the central lobe of a directional antenna's radiation pattern, the sidelobes referring to the lesser lobes of progressively decreasing amplitude on both sides of the mainlobe and often extending rearwardly of the mainlobe.
  • Radar antenna aperture configuration generally determines the extent and relative magnitude of the associated sidelobes; however, the gain of the strongest one of the sidelobes is typically only about 1/64 that of the mainlobe. In terms of decibels, the strongest sidelobe gain is typically down about 18dB from the associated mainlobe gain. Gains of the other sidelobes are usually considerably smaller than that of the strongest sidelobe. Although sidelobe gain is typically much smaller than mainlobe gain, because of the large solid angle into which sidelobes radiate, as compared to the small solid angle into which the mainlobe radiates, typically about 25 percent of the total power radiated by a uniformly illuminated radar antenna are in the sidelobes.
  • sidelobe radiation provides no useful function and in addition to representing wasted radiating power has other serious disadvantages.
  • radar clutter from sidelobe returns increases the difficultly of discriminating targets from background.
  • Another very significant disadvantage of sidelobe radiation is that such radiation can, in a military environment, be utilized by hostile forces for electronically jamming the radar and can also be used for positionally locating and for guiding munitions to the radar.
  • mainlobe radiation is ordinarily much greater than sidelobe radiation, its relatively small solid angle of radiation and its directionality makes mainlobe jamming, radar location and munitions direction more difficult.
  • the present invention is starting from a prior art solid state phased array antenna as it is known from "IEEE MTT-S International Microwave Symposium Digest", 15-17 June 1982, Dallas, Texas, IEEE (New York, US), D.N. McQuiddy Jr; "Solid state radar's path to GaAs", pages 176-178.
  • This known solid state phased array antenna is comprising an antenna aperture formed of a large number of N individual, closely spaced radiating apertures and a number of N individual radiating elements, each of which is operatively associated with a corresponding one of the a.m. radiating apertures for radiating microwave energy therethrough.
  • phased array antennas of that type A general problem of phased array antennas of that type is the suppression of sidelobe radiation; that is to say, the gain of sidelobe radiation should be much less than the gain of the mainlobe radiation. This is because the sidelobe radiation not only is a waste of radiating energy but also has other serious disadvantageous such as increased difficulty of discriminating targets. It, therefore, has already been proposed to suppress such sidelobe radiation in passive array antennas by "tapering" the illumination over the aperture so that individual radiating elements near the side edges of the array radiate less energy than elements which are closer to the center.
  • the power modules are subdivided in a number of M groups, the number M being significantly less than the number N , these M groups of the power modules furthermore being arranged in a concentric pattern (see Fig.4) around a central point of the array, wherein the output voltage amplitude of the power modules is equal within each group, but different in different groups.
  • a.m. measures it is possible to easily reduce the sidelobe gain to be at least 30 dB below the mainlobe gain by selecting the output voltage amplitude of each group of power modules and by in combination selecting a pattern dimension of each group.
  • a sufficient sidelobe suppression can be obtain by merely using between 3 and 10 different types of power modules, neither production costs are substantially increased nor maintenance and logistical support problems are caused.
  • US-A-3 760 345 there is disclosed a transducer array for receiving or transmitting acoustical or electromagnetic signals by means of uniform square transducer elements which each are coupled to associated shading resistances.
  • This known array is of the passive type and, consequently, has not a plurality of power modules in the sense of feature [c] of the preamble of claim 1.
  • FIG. 1 there is shown in FIG. 1, in exploded form, an exemplary, solid state, active array antenna 10 of the general type with which the present invention may be used to advantage.
  • antenna 10 which is shown as an aircraft-mounted type, are an aperture assembly 12, a cooling liquid plate assembly 14, a solid state power module assembly 16 and a stripline feed assembly 18.
  • aperture assembly 12 Included in aperture assembly 12 is a large number of small radiating elements 24, each of which has disposed therein a dielectric filler 26.
  • a face 28 of aperture assembly 12 is a large number of openings 30, each of such openings being associated with one of radiating elements 24.
  • Mounted on cooling plate assembly 14 are a number of loop assemblies 32, each of which is also associated with one of radiating elements 24.
  • a large number of solid state power modules 34 comprise power module assembly 16, each such module preferably, but not necessarily, powering only a single associated radiating element 24.
  • FIG. 2 illustrates a typical radiation pattern 38 associated with a radar carried by an aircraft 40.
  • the airborne radar involved may, for example, comprise a solid state active array similar to array 10 depicted in FIG. 1.
  • radiation pattern 38 comprises a narrow, beam-shaped mainlobe 42 and smaller, fan-shaped sidelobes 44 on each side of the mainlobe.
  • Sidelobes 44 comprise several different lobes 46 which fan out at different angles, ⁇ , relative to a main beam axis 48; typically the sidelobes diminish in intensity as the angle, ⁇ increases. It can further be seen from FIG. 2 that some of lobes 46 extend rearwardly relative to mainlobe 42, the angles, ⁇ , associated therewith being greater than 90°.
  • the present invention relates to a process for configuring a solid state, active array so that the far field sidelobe gain is at least 30dB down, from the far field mainlobe gain.
  • the reduced sidelobes provided by the present invention is accomplished by tapering the radiating illumination in a relatively few, precisely determined steps.
  • array 60 corresponds generally to array 10 (FIG. 1), insofar as general construction is concerned.
  • array 60 has rectangular dimensions 2a and 2b, and has R rows and C columns of linearly polarized, rectangular radiating elements 62.
  • element 6z Associated with element 6z is a power module 64 (shown in phantom lines).
  • array 60 has an elliptically (instead of a rectangular) radiating aperture 66, it having been determined by the present inventors that array corner regions 68 contribute only negligibly to sidelobes.
  • the far field, G, associated with radiating aperture 66 is considered, the far field at any point defined by angles ⁇ and ⁇ being generally identified as G( ⁇ , ⁇ ) in FIG. 3.
  • a principal feature of the present invention is the dividing, for analysis purposes, of radiating aperture 66 into a relatively few, superimposed elliptical zones around a central point "A", and the selection of zone boundary axes a i , b i and the zone voltage amplitudes, E i , associated therewith in a manner providing a tapered illumination of the aperture which assures very low, far field sidelobes.
  • the number of elliptical zones selected varies between 3 and about 10 and more preferably between 3 and only about 7. Insufficient illumination tapering is considered to be provided using less than 3 zones and although smoother tapering can be provided by use of more than about 7 zones, the cost of using more than that number of different types of power modules is costly and has moreover, been found by the present inventors to be unnecessary for achieving very low sidelobes.
  • the number of zones shown and described is 5; however, any limitation to the use of about 5 zones is neither intended nor implied.
  • First through fifth concentric, progressively larger elliptical zones 74, 76, 78, 80 and 82, respectively, are thus selected, the zones having semi-major and semi-minor axes equal, respectively, to a1, a2, a3, a4, and a5 and b1, b2 b3, b4, and b5 (FIG. 4).
  • First zone 74 is the smallest zone and fifth zone 82 is the largest zone and completely fills aperture 66, dimensions a5 and b5 being, therfore, respectfully equal to aperture dimensions a and b (FIG. 3).
  • zones 74, 76, 78, 80 and 82 are, for analysis purposes, considered as stacked (or superimposed) upon one another, with the fifth, largest zone 82 at the bottom and the first, smallest zone 74 at the top.
  • a different voltage amplitudes, E i amplitude E1 being associated with zone 74, E2 with zone 76, E3 with zone 78, E4 with zone 80 and E5 with zone 82.
  • the voltage amplitudes, E i are added to establish power module voltage.
  • the combined voltage amplitude of the stacked zones 74-82 required to be provided by underlying power modules 60 is equal to E1 + E2 + E3 + E4 + E5 .
  • the voltage amplitude required to be provided by underlying power modules 60 is equal to E2 + E3 + E4 + E5 ; in an annular region 88 of third zone 78 outside of second zone 74, the voltage amplitude required to be provided by the underlying power modules is equal to E3 + E4 + E5 .
  • each zone 74-82 can be treated separately as providing only a single, corresponding voltage amplitude E1-E5.
  • the present process treats all zone axis dimensions, a i , b i , and zone voltage amplitudes, E i , as independent variables. At least one set of values for these variables is computed which will provide, as may be required, either minimum sidelobes or a sidelobe gain which is a preselected number of dB less than the corresponding mainlobe gain.
  • a i , b i , E i standard techniques of gradient search can be employed.
  • an initial set of parameters is chosen as a starting point, and a present maximum sidelobe level (such as -30 dB) is selected as a performance criterion.
  • the antenna far field pattern with the initial set of input parameters can be calculated by using Equation (1).
  • the total power of all the sidelobes that exceed the present level, being defined as the error is computed. After this a small variation of one of the parameters, either a positive or negative increment, is introduced and the error is recomputed.
  • antenna pattern gain (in dB) against elevation angle, ⁇ as measured from the broadside axis. From FIG 7 it can be seen that the gains of all sidelobes 46 (shown shaded) are down at least about 36dB from the peak (0°) gain of mainlobe 42 over the entire visible radiation range.
  • FIG. 8 which shows that the highest sidelobe gain is down at least about 37 dB from the peak mainlobe gain.

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  • Variable-Direction Aerials And Aerial Arrays (AREA)

Abstract

Un appareil d'antenne à réseau à semi-conducteurs à faible rayonnement du lobe latéral comprend une grande ouverture de rayonnement divisée en un grand nombre N, de petites ouvertures de rayonnement étroitement espacées, chaque petite ouverture de rayonnement étant associée à un élément de rayonnement et à un module de puissance à semi-conducteurs polarisé linéairement. La grande ouverture de rayonnement est divisée en M, de préférence entre 3 et environ 10 zones de rayonnement concentriques, de forme elliptique et de dimensions différentes, superposées les unes sur les autres, à des fins d'analyse. Chacune de ces zones possède une amplitude de tension de sortie Ei, et des axes semi-majeurs et semi-mineurs de longueurs respectives, ai et bi, chaque zone étant considérée séparément dans l'équation du champ éloigné G(,PHI) = [f(,PHI) (â cos PHI - âg(F) sin PHI cos ) ]2, dans laquelle f(,PHI) = (I), ui = (II), J1(ui) est la fonction de Bessel de premier ordre, â et âPHI sont des vecteurs unitaires dans les coordonnés sphériques et Ko est le nombre d'ondes associées au champ de rayonnement. A l'aide de l'équation du champ éloigné, les valeurs de Ei, ai et bi pour chaque zone sont calculées, d'où il résulte un gain de crête du lobe latéral du champ éloigné qui se trouve à un minimum ou un nombre spécifique de dB, par exemple au moins 30dB, en dessous du gain du lob principal du champ éloigné. Les valeurs de Ei dans les zones de chevauchement sont aditionnées pour établir les amplitudes de tension requises des modules de puissance sous-jacents associés aux N ouvertures de rayonnement.

Claims (10)

  1. Antenne à réseau piloté en phase à semiconducteurs à faibles lobes latéraux ayant un lobe principal en champ lointain et un diagramme de rayonnement des lobes latéraux, comprenant:
    [a] une ouverture d'antenne (12) formée d'un grand nombre N d'ouvertures rayonnantes individuelles étroitement espacées (30);
    [b] un certain nombre d'éléments rayonnants individuels (24), chacun d'entre eux étant associé fonctionnellement à l'une oui lui correspond desdites N ouvertures rayonnantes (12) pour rayonner une énergie hyperfréquence par l'intermédiaire de celle-ci; et
    [c] un certain nombre de modules de puissance à semiconducteurs individuels (34), dont chacun est fonctionnellement associé à au moins l'un desdits N éléments rayonnants (24) pour leur fournir de la puissance en fonction de l'amplitude de tension de sortie (E) du module de puissance à semiconducteur respectif (34)
       caractérisée en ce que
    [d] lesdits modules de puissance (34) sont subdivisés en un nombre de M groupes, le nombre M étant de préférence compris entre 3 et 10 et étant sensiblement inférieur audit nombre N;
    [d.1] lesdits M groupes desdit's modules de puissance (34) sont disposés selon un motif concentrique (figure 4) autour d'un point central (A) dudit réseau;
    [d.2] ladite amplitude de tension de sortie (E) desdits modules de puissance à semiconducteurs (34) est la même à l'intérieur de chaque groupe, mais différente dans des groupes différents; et en ce que
    [e] ladite amplitude de tension de sortie (E) de chaque groupe et une dimension de motif de chaque groupe sont sélectionnées en association de telle façon que le gain des lobes latéraux soit inférieur d'au moins 30 dB au gain du lobe principal.
  2. Antenne à réseau selon la revendication 1, dans laquelle le nombre M est d'environ 5.
  3. Antenne à réseau selon la revendication 1 ou 2, dans laquelle la frontière extérieure de chacun desdits M groupes de modules de puissance est de forme elliptique, chacune desdites frontières ayant un demi-grand axe de longueur ai et un demi-petit axe de longueur bi, l'indice "i" désignant la ième frontière.
  4. Antenne à réseau selon la revendication 3, dans laquelle les amplitudes des tensions de sortie et l'agencement desdits M groupes de modules de puissance sont sélectionnés en traitant les agencements des M groupes de modules comme s'il s'agissait d'une superposition de M zones de forme elliptique se chevauchant ayant les mêmes frontières que ceux qui leur correspondent desdits M groupes de modules, une amplitude de tension différente Ei étant associée à chacune desdites M zones, l'amplitude de tension des modules de puissance dans chacun desdits M groupes étant sélectionnée par addition des différentes amplitudes de tension Ei des zones correspondantes se chevauchant, l'indice "i" désignant la ième zone.
  5. Antenne à réseau selon la revendication 4, dans laquelle les amplitudes de tension Ei et les longueurs des demi-axes ai et bi sont sélectionnées par application de l'équation de champ lointain suivante pour faire en sorte que le gain des lobes latéraux soit inférieur d'au moins environ 30 dB par rapport au gain du lobe principal:

    G(ϑ,φ) = [f(ϑ,φ) (â ϑ cos φ - â φ sin φ cos ϑ)]²,
    Figure imgb0024
    Figure imgb0025
     u i = (k o a i sin ϑ) √ cos²φ + (b i ²/a i ²) sin² φ, ¯
    Figure imgb0026

    où: J₁(ui) est la fonction de Bessel du premier ordre,
       âϑ et âφ sont des vecteurs unités dans un système de coordonnées sphériques et ko est le nombre d'onde associé au champ rayonné.
  6. Procédé pour configurer une antenne à réseau conformément au préambule de la revendication 1, caractérisé par les étapes consistant à:
    [1] subdiviser lesdits modules de puissance (34) en un nombre de M groupes, le nombre M étant de préférence compris entre 3 et 10 et étant sensiblement inférieur audit nombre N;
    [1.1] agencer lesdits M groupes desdits modules de puissance (34) selon un motif concentrique (figure 4) autour d'un point central (A) dudit réseau,
    [1.2] rendre lesdites amplitudes de tension de sortie (E) desdits modules de puissance (34) égales les unes aux autres à l'intérieur de chaque groupe, mais différentes dans des groupes différents; et
    [2] sélectionner en association ladite amplitude de tension de sortie (E) de chaque groupe et une dimension de motif de chaque groupe de façon à ce que le gain des lobes latéraux soit inférieur d'au moins environ 30 dB au gain du lobe principal.
  7. Procédé selon la revendication 6, dans lequel le nombre M est d'environ 5.
  8. Procédé selon la revendication 6 ou 7, comportant l'étape consistant à agencer lesdits M groupes de modules de puissance de façon à ce que leurs frontières extérieures soient de forme sensiblement elliptique, chaque frontière ayant un demi-grand axe de longueur ai et un demi-petit axe de longueur bi, où l'indice "i" désigne la ième frontière.
  9. Procédé selon la revendication 8, comportant les étapes consistant à:
    [1] traiter lesdits M groupes de modules de puissance comme s'il s'agissait d'une superposition de M zones de forme elliptique se chevauchant ayant les mêmes frontières que ceux qui leur correspondent des M groupes de modules, une amplitude de tension Ei étant associée à chacune desdites M zones, et
    [2] traiter l'amplitude de tension des modules de puissance dans chacun desdits M groupes de modules de puissance comme s'il s'agissait d'une superposition additive des amplitudes de tension Ei des zones correspondantes se chevauchant, l'indice "i" désignant la ième zone.
  10. Procédé selon la revendication 9, comportant l'étape consistant à utiliser l'équation de champ lointain suivante pour obtenir les valeurs des amplitudes de tension Ei des zones, et les longueurs des demi-grands axes et demi-petits axes ai et bi des zones, de façon que le gain des lobes latéraux en champ lointain soit inférieur d'au moins 30 dB au gain du lobe principal en champ lointain correspondant :

    G(ϑ,φ) = [f(ϑ,φ) (â ϑ cos φ - â φ sin φ cos ϑ)]²,
    Figure imgb0027
    Figure imgb0028
     u i = (k o a i sin ϑ) √ cos²φ + (b i ²/a i ²) sin² φ, ¯
    Figure imgb0029

    où: J₁(ui) est la fonction de Bessel du premier ordre,
       âϑ et âφ sont des vecteurs unités dans un système de coordonnées sphériques et ko est le nombre d'onde associé au champ rayonné.
EP19870905342 1986-07-29 1987-07-21 Appareil d'antenne a reseau a dephasage a semi-conducteurs a faible rayonnement des lobes laterals Expired - Lifetime EP0275303B1 (fr)

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US89145686A 1986-07-29 1986-07-29
US891456 1986-07-29

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US5102620A (en) * 1989-04-03 1992-04-07 Olin Corporation Copper alloys with dispersed metal nitrides and method of manufacture
US5039478A (en) * 1989-07-26 1991-08-13 Olin Corporation Copper alloys having improved softening resistance and a method of manufacture thereof
GB2238176A (en) * 1989-10-21 1991-05-22 Ferranti Int Signal Microwave radar transmitting antenna
FR2659500B1 (fr) † 1990-03-09 1992-05-15 Alcatel Espace Procede de formation du diagramme d'une antenne active a haut rendement pour radar a balayage electronique et antenne mettant en óoeuvre ce procede.
US5422647A (en) * 1993-05-07 1995-06-06 Space Systems/Loral, Inc. Mobile communication satellite payload
IL110896A0 (en) * 1994-01-31 1994-11-28 Loral Qualcomm Satellite Serv Active transmit phases array antenna with amplitude taper
US5539415A (en) * 1994-09-15 1996-07-23 Space Systems/Loral, Inc. Antenna feed and beamforming network
FR2783974B1 (fr) * 1998-09-29 2002-11-29 Thomson Csf Procede d'elargissement du diagramme de rayonnement d'une antenne, et antenne le mettant en oeuvre
GB0213976D0 (en) 2002-06-18 2002-12-18 Bae Systems Plc Common aperture antenna
US7460077B2 (en) * 2006-12-21 2008-12-02 Raytheon Company Polarization control system and method for an antenna array

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US3553706A (en) * 1968-07-25 1971-01-05 Hazeltine Research Inc Array antennas utilizing grouped radiating elements
US3760345A (en) * 1972-08-28 1973-09-18 Us Navy Adapting circular shading to a truncated array of square elements
US3811129A (en) * 1972-10-24 1974-05-14 Martin Marietta Corp Antenna array for grating lobe and sidelobe suppression
US4052723A (en) * 1976-04-26 1977-10-04 Westinghouse Electric Corporation Randomly agglomerated subarrays for phased array radars

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WO1988001106A1 (fr) 1988-02-11
DE3787797T2 (de) 1994-04-21
JPH01500476A (ja) 1989-02-16
EP0275303A1 (fr) 1988-07-27
DE3787797D1 (de) 1993-11-18

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