Communications: directive radio wave systems and devices (e.g. – Directive – Including polarized signal communication transmitter or...
Patent
1990-08-28
1992-06-23
Issing, Gregory C.
Communications: directive radio wave systems and devices (e.g.,
Directive
Including polarized signal communication transmitter or...
342383, 342448, H01Q 300, G01S 316, G01S 504
Patent
active
051247119
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a device for auto-adaptative direction and polarization filtering of radio waves received on a network of aerials coupled to a receiver.
The invention is applied in particular to the construction of an interference elimination device for receivers of electromagnetic waves travelling through the HF ionospheric channel.
It is known that a tactical high frequency reception aerial must in particular enable any user to establish radio connections with various transmitting stations, and to simultaneously hear the transmissions from the other users of the high frequency channel.
Bearing in mind the congestion of the high frequency channel, the receiver must be able to reject the signals coming from sources of interference, be they intentional or not.
However, the known tactical high frequency adaptative aerial networks, generally formed from several suitably spaced vertical whips, do not enable exploitation of the polarization of the ionospheric waves. Whilst the performance levels expected from an adaptative aerial formed from three orthogonal dipoles, which does not have the shortcomings of the whips, are described in an article by RTE COMPTON entitled "The tripole antenna: an adaptative array with a full polarization flexibility" (IEEE trans antenne and propagation. Vol.: AP 29 No. 6 Nov. 81), the aerial which is described therein has the tactical disadvantage of having to be placed at the top of a mast so that the radiation patterns of the horizontal dipoles are correct. Moreover, as it is technologically very difficult to suppress the high frequency currents circulating in the external parts of the coaxial cables connecting the dipoles of the aerial to the receiver, the performance levels expected of this aerial configuration are, in practice, not obtained.
SUMMARY OF THE INVENTION
The aim of the invention is to overcome the abovementioned disadvantages.
To this end, the subject of the invention is a device for auto-adaptative direction and polarization filtering of radio waves received on a network of aerials coupled to a receiver. The device is characterized in that the network of aerials is formed by Q crossed loops disposed around a common axis in accordance with adjacent dihedrons of equal angular value, and by a rectilinear filar aerial of longitudinal axis merged with the common axis. The Q loops and the rectilinear filar aerial have a same phase centre situated at the output terminals of the Q loops and at one end terminal of the filar aerial. The Q loops and filar aerial are respectively coupled to an operand input of a summation circuit with Q+1 inputs across Q+1 multiplication circuits for multiplying a value X.sub.j provided by each loop and the filar aerial by a complex weighting coefficient W.sub.j ; which is adjustable as a function of the variations of the polarization of the received ionospheric wave, its azimuthal, and site arrival direction. The addition of the products X.sub.j.W.sub.j gives a resultant signal which can be exploited by the receiver with a maximum useful signal
oise ratio.
The aerial according to the invention has the main advantages of being auto-adaptative, having a wide band, reduced dimensions, and possessing radiation properties which are suitable for all distances less than 2000 kilometers.
The active receiving structure, obtained by virtue of the amplifiers placed at the phase centre of each aerial, enables obtainment of a wide band aerial operation on an extensive range of frequencies comprised between 2 and 30 MHz. Moreover, the crossed loops and the monopole which form the passive part of the antenna enable obtainment of distinct amplitude/phase responses for any elliptically polarized ionospheric wave transmitted in accordance with a specified site angle and azimuth. Because of this, the linear combination of these responses enables elimination of interference in adaptative receiving mode and diminution of the fading of the useful signal in the absence of interference.
BRIEF DESCRIPTION OF THE DR
REFERENCES:
patent: 4612549 (1986-09-01), Geyer, Jr. et al.
patent: 4675685 (1987-06-01), Finken
Lamberty et al. Interference Suppression Using an Adaptive Polarization Combiner, Proc. of 1987 Antenna Applications Symposium, Sep. 23-25, 1987 pp. 1-15.
Bull et al. A Broadband Electrically Small Adaptive Array, 1986 Int. Symposium Digest Antennas and Propagation, Jun. 8-13, 1986 pp. 993-996.
WO, A 86/01340 (Ostereichisches Forschungszentrum Seiberdorf) Feb. 27, 1986, see FIGS. 1, 3, 4, 6, 7, p. 3, lines 4-10; p. 4, line 10-p. 6, line 8.
IEEE Transactions on Aerospace and Electronic Systems, vol. AES-9 No. 6, Nov. 1973, IEEE, (New York, US), H. S. Lu: "Polarization Separation by an adaptive filter", pp. 954-956.
IEEE Transactions on Aerospace and Electronic Systems, vol. AES-21, No. 6, Nov. 1985, IEEE, (New York, US), Y. Ogawa et al.: "An LMS adaptive array using a pilot signal", pp. 777-782.
Seguineau Jean-Christophe
Sorais Daniel
"Thomson-CSF"
Issing Gregory C.
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