EP0320553B1 - Système adaptatif d'antennes - Google Patents

Système adaptatif d'antennes Download PDF

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Publication number
EP0320553B1
EP0320553B1 EP19870311217 EP87311217A EP0320553B1 EP 0320553 B1 EP0320553 B1 EP 0320553B1 EP 19870311217 EP19870311217 EP 19870311217 EP 87311217 A EP87311217 A EP 87311217A EP 0320553 B1 EP0320553 B1 EP 0320553B1
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EP
European Patent Office
Prior art keywords
adaptive
processor
output
loop
antenna
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EP19870311217
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German (de)
English (en)
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EP0320553A1 (fr
Inventor
Andrew Jonathan Fellows Malcolm
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Nortel Networks Ltd
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Northern Telecom Ltd
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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

  • This invention relates to antenna systems and in particular to steered adaptive antenna systems.
  • the beam pattern of an antenna array is determined by the type of elements in the array, their orientations and position in space and the amplitude and phase of the currents induced in the elements.
  • An adaptive antenna array modifies the pattern in accordance with some control criteria whereby, for example, to steer the beam.
  • adaptive antenna systems comprising a plurality of antenna elements and adaptive processor means for processing signals from the antenna elements whereby to steer an adaptive beam pattern, wherein the adaptive processor means applies adaptive complex weights to the amplitudes and phases of the signals from the antenna elements.
  • British patent application GB 2 178903 A discloses an adaptive beamforming network to which the output signals of an array of antenna elements are applied.
  • the summed output of the network forms an 'ERROR' feedback signal which is correlated with each element signal and applied to a limiter the output of which is added to a steering component.
  • the resultant derived value is used to drive a weight coefficient associated with the output of the antenna array element.
  • US patent 4,635,063 discloses an adaptive antenna including an array of elements. A feedback signal is derived from the weighted summed outputs of the elements, the feedback signal being correlated with the element signals.
  • the outputs of the correlators are transformed by algorithms in individual computing means to generate weighting signals for the associated element outputs.
  • the optimum reception of desired signals may be adversely affected by the presence of one or more unwanted interference or jamming signals.
  • an adaptive antenna array for the receiver it is however possible to modify the associated radiation pattern of the array to create a null(s) centred on the direction of the incoming jamming signal(s).
  • the position of the transmitter, or angle of arrival, of a wanted signal is known to a moderate degree of accuracy, such that the signal can be put very nearly at the peak of the beam of a beam steering antenna.
  • the signal to noise plus interference ratio SNIR
  • the angle of arrival of the wanted signal is known to a very high degree of accuracy, then a steered beam implementation of the Wiener-Hopf solution:
  • a system which is capable of broad acceptance to main lobe signals, whilst retaining the ability to steer nulls towards jamming signals arriving via the side lobes, is thus desirable for various applications.
  • an adaptive antenna system comprising a plurality of antenna elements and adaptive processor means for processing signals from the antenna elements whereby to steer an adaptive beam pattern, wherein the adaptive processor means applies adaptive complex weights to the amplitudes and phases of the signals from the antenna elements, characterised in that the adaptive complex weights have inphase and quadrature components and the adaptive processor means includes means for applying variable, but equal, bounding limits to each individual inphase and quadrature component of each adaptive complex weight.
  • Fig. 1 which by way of example, shows the output signal to noise ratio for a single misaligned -10dB source for various processor configurations and misalignments between the processor look direction and the signal angle of arrival, with a thermal noise level at -50dB, the array natural beam width being approximately 21 ° .
  • Curve (a) of Fig. 1 corresponds to the known optimum weight solution as defined by the Wiener-Hopf equation (1) with "artifical" noise added at a level of -40dB and clearly shows inadequate output signal to noise ratio for misalignments of 1/8° or more.
  • Curve (b) maintains gain towards the signal, with adequate signal to noise ratio to beyond 16 misalignment, but with no ability to place nulls against other, unwanted, sources.
  • Curve (c) represents the performance of the weight bounding processor of the present invention which, while 10dB lower than the conventional beam former, retains the important ability to null unwanted signals.
  • Fig. 2 shows the weight norm growth of the Wiener-Hopf weight set for two -10dB sources, one fixed, the other swept through the mainlobe, for various fixed source positions and artificial noise levels, with thermal noise at -50dB .
  • Curve (a) corresponds to the fixed source located at 35 °, well into the sidelobes, with artificial noise at - 40dB, and shows a rapid increase in weight norm away from perfect alignment.
  • the misalignment is less than approximately 5°, no significant reduction in output signal level occurs.
  • signal to noise degradation for a misaligned signal is achieved by increasing the weight norm and hence noise output level instead of reducing the signal output level.
  • the basic structure of the processor loop employed is indicated schematically in Fig. 3. It is based on a conventional steered adaptive control loop using a time-shared digital correlator and serves to "remove" jammers prior to subsequent processing by means (not shown) following summer 1.
  • Each loop includes a weighting network 2 and the outputs of the various weighting networks 2 are applied to summer 1 which is common.
  • Signals from the summer 1 are digitised by ADC (analogue-to-digital converter) 4 and negated by network 7 prior to being passed to digital correlator 12.
  • the signal from antenna element A is digitised by ADC 3 and the complex conjugate of this digital signal determined by network 5 and passed to the digital correlator 12.
  • the correlation result from correlator 12, with the appropriate steering vector added thereto as indicated at adder 10, is passed to a bounding network 11.
  • the network 11 compares the current correlation (weight) with the value contained in a memory and outputs either the weight or the bound, dependent on the result of the comparison.
  • the output is converted back to analogue form and the voltage produced by the digital- to-analogue converter (DAC) controls the weight applied by network 2.
  • DAC digital- to-analogue converter
  • the digital correlator 12 comprises a multiplier 6, an amplifier 8 and a leaky integrator 9, in series but not necessarily in that order.
  • Fig. 5 illustrates a more specific digital processor configuration, like reference numerals being used for equivalent elements, which employs a single processor loop.
  • Associated with each antenna element A 1 to An is a respective weighting network 2 1 to 2 n , the outputs of which are applied to the common summer.
  • Signals from the elements A 1 to An are selected in turn by an analogue multiplexer 13, digitised by ADC 3, and the complex conjugate of the output of ADC 3 applied to the complex multiplier 6 of the digital correlator which in the processor configuration illustrated in Fig. 5 is combined with the means for adding the steering vector (10-Fig.3) to form a digital correlator and beam steering network 12 1 .
  • the network 12 1 consists of five parts; the complex multiplier 6; a multiplier-accumulator 14; a parameter memory 15; a correlation memory 16 and a steering vector memory 17.
  • the correlation result from network 12 1 is passed to the bounding network 11 which consists of three parts; a comparater 18; a multiplexer 19 and a bound memory 20.
  • the network 11 compares the current correlation (weight) with the value held in the bound memory 20 and outputs either the weight or the bound, dependent on the result of the comparison.
  • This weight (or bound) is directed to the appropriate DAC, 22, to 22 n , by a demultiplexer 21, the voltage produced by the DAC controlling the weight applied by the appropriate weighting network 2 1 to 2 n .

Landscapes

  • Variable-Direction Aerials And Aerial Arrays (AREA)

Claims (7)

1. Système adaptatif d'antennes comportant plusieurs éléments d'antenne et des moyens formant processeurs adaptatifs pour traiter des signaux fournis par les éléments d'antenne, permettant d'orienter un diagramme de rayonnement adaptatif, système dans lequel les moyens formant processeur adaptatifs appliquent des pondérations complexes adaptatives aux amplitudes et aux phases des signaux fournis par les éléments d'antenne, système caractérisé par le fait que les pondérations complexes adaptatives présentent des composantes en phase et en quadrature et par le fait que les moyens formant processeurs adaptatifs incluent des moyens pour appliquer des limitations variables, mais égales, à chaque composante individuelle en phase et en quadrature de chaque coefficient de pondération complexe adaptatif.
2. Système adaptatif d'antennes selon la revendication 1, caractérisé par le fait qu'à chaque élément d'antenne est associée une boucle respective formant processeur adaptatif de commande d'orientation du diagramme, chaque dite boucle formant processeur appliquant des coefficients de pondération complexes adaptatifs à l'amplitude et à la phase d'un signal fourni par l'élément d'antenne respectif et générant des coefficients de pondération complexes adaptatifs actualisés pour application au signal fourni par l'élément d'antenne respectif dans un cycle suivant de ladite boucle formant processeur, lesquels coefficients de pondération complexes adaptatifs présentent des composantes en phase et en quadrature, et système dans lequel chacune des boucles comporte des moyens pour appliquer des limites, variables, mais égales, à la valeur de chaque componsante individuelle, en phase et en quadrature, de chaque coefficient de pondération complexe adaptatif, ce qui permet de limiter la croissance du bruit de sortie en présence d'un signal désaligné tout en conservant l'aptitude à supprimer le brouillage par les lobes secondaires.
3. Système adaptatif d'antennes comme revendiqué dans la revendication 2, dans lequel chaque boucle formant processeur inclut un réseau de pondération, et dans lequel les signaux de sortie des réseaux de pondération sont additionnés dans un additionneur commun.
4. Système adaptatif d'antennes comme revendiqué dans la revendication 3, dans lequel chaque boucle formant processeur inclut des moyens respectifs pour corréler un conjugué complexe du signal de sortie de l'élément d'antenne respectif et une version négative du signal de sortie de l'additionneur commun, système dans lequel des moyens sont prévus pour additionner un vecteur d'orientation respectif avec le signal de sortie des moyens de corrélation avant son application auxdits moyens de limitations des coefficients de pondération complexes adaptatifs et système dans lequel le signal de sortie des moyens de limitation des coefficients de pondération complexes adaptatifs est employé pour commander le réseau de pondération.
5. Système adaptatif d'antennes comme revendiqué dans la revendication 4, dans lequel les moyens de corrélation comportent, fonctionnellement, en série, un multiplicateur, un amplificateur et un intégrateur à fortes fuites, non nécessairement dans cet ordre.
6. Système adaptatif d'antennes comme revendiqué dans la revendication 1, dans lequel les moyens formant processeurs adaptatifs incluent un circuit de pondération respectif associé à chaque élément d'antenne, les signaux de sortie de ces éléments de pondération étant envoyés à un additionneur commun, et système qui comporte une boucle commune formant processeur de commande adaptatif d'orientation du diagramme pour chaque élément d'antenne du système, boucle de processeur qui génère des coefficients de pondération complexes adaptatifs actualisés et qui comporte lesdits moyens d'orientation et d'application d'une limitation, les signaux fournis par lesdits éléments d'antenne étant sélectionnés par un multiplexeur de la boucle et le signal de sortie de la boucle étant envoyé au démultiplexeur correspondant de la boucle.
7. Système adaptatif d'antennes comme revendiqué dans la revendication 6, dans lequel la boucle formant processeur commun inclut des moyens pour corréler un conjugué complexe d'un signal fourni par un élément d'antenne et une version négative du signal de sortie de l'additionneur commun, pour ajouter un vecteur d'orientation approprié au signal de sortie des moyens de corrélation, et pour appliquer le signal de sortie des moyens de corrélation, avec le vecteur d'orientation qui lui est ajouté, à des moyens de limitation des coefficients de pondération complexes adaptatifs, système dans lequel lesdites limites sont appliquées avant envoi au démultiplexeur.
EP19870311217 1987-12-18 1987-12-18 Système adaptatif d'antennes Expired - Lifetime EP0320553B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP19870311217 EP0320553B1 (fr) 1987-12-18 1987-12-18 Système adaptatif d'antennes
DE19873783771 DE3783771T2 (de) 1987-12-18 1987-12-18 Adaptives antennensystem.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19870311217 EP0320553B1 (fr) 1987-12-18 1987-12-18 Système adaptatif d'antennes

Publications (2)

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EP0320553A1 EP0320553A1 (fr) 1989-06-21
EP0320553B1 true EP0320553B1 (fr) 1993-01-20

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6823174B1 (en) 1999-10-11 2004-11-23 Ditrans Ip, Inc. Digital modular adaptive antenna and method

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4635063A (en) * 1983-05-06 1987-01-06 Hughes Aircraft Company Adaptive antenna
GB2178903B (en) * 1985-08-07 1989-09-20 Stc Plc Adaptive antenna

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EP0320553A1 (fr) 1989-06-21
DE3783771D1 (de) 1993-03-04
DE3783771T2 (de) 1993-05-06

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