D. D. Ganzy - Dr.Sc. (Eng.), Head of Department, JSC - SRC "Vigstar" (Moscow) E-mail: ntc@vigstar.ru P. V. Rusakov - Head of Sector, Center «NIIRP», JSC "Almaz-Antey" (Moscow) E-mail: rp258rt@rambler.ru E. E. Fotin - Deputy Head of Department, NIITs (Mytishchi) G. I. Troshin - Dr.Sc. (Eng.), Professor, Leading Research Scientist, JSC - SRC "Vigstar" (Moscow)

The article is devoted to analysis of efficiency of the receiving adaptive antenna array (AAA) in the conditions of presence of direct external interference and interference due to multipath propagation of radio waves. The interference signals with relative power νi arrive from the directions θi, and the signals caused by multipath propagation are represented by set of the signals arriving from other directions with the casual coefficients of reflections from relief, local subjects and with casual phases concerning a phase of a direct beam. For option of AAA with 16 radiators at simultaneous action of two direct and seven delayed interferences under different angles the system of the differential equations describing process of adaptation of spatial and temporary characteristics of this array at additional impact of multipath propagation has been investigated. The first and second direct interferences come from the directions of θ1 = -40 deg and θ2 = 60 deg respectively. Powers of the first and second interferences are equal 20 dB and 30 dB (ν1 = 100 relative units, and ν2 = 1000 relative units) concerning noise level respectively. Phases of the lagging signals in relation to phases of direct signals are defined by their difference. The decision of the system of differential equations has been carried out with attraction of a package of MATLAB 7.10.0 applied programs. A working frequency band of a receiving AAA is equal to 7,25...7,75 GHz, the wavelength corresponding to the central frequency λ = 4 cm, a frequency band of the working channel (trunk) Δfc = 36 MHz, distance between radiators d = λ/2 = 2 cm. For the chosen variant of modeling of multipath propagation of interferences it has been shown that satisfactory compensation of these interferences even in the absence of correlation between direct and lagging signals takes place as number of interferences is less than number of adaptive channels. Time of adaptation T to all chosen plots of the signal and interfering situation is no more than 2 ms. A total level of interferences at the output of AAA after adaptation in the absence of multipath propagation of radio waves and at the specified levels of the operating interferences (20 dB and 30 dB concerning noise level) is less than -70 dB. The total level of interferences at the exit of an adaptive antenna array after adaptation, in the presence of the reflected interferences due to multipath propagation of the radio waves but which aren\'t getting to the main lobe of the directional pattern and at the same levels of direct interferences is less than 0 dB concerning noise level. The offered method of calculation of degree and rate of suppression of the interfering signals can be applied to a preliminary estimate of overall performance of a receiving AAA on the concrete radio path on which at the same time there are useful and interfering signals including due to multipath propagation of radio waves.

 

1. Ganzijj D.D., Rusakov P.V., Troshin G.I. Adaptacija priemnojj fazirovannojj antennojj reshetki v celjakh pomekhozashhity radiosvjazi v sluchae neskolkikh prostranstvennykh pomekh // Antenny. 2014. № 10. S. 33-36.
2. Vural A.M. Effects of perturbation on the performance of optimum/adaptive arrays // IEEE Trans. Aerospace and Electron. Syst. 1979. V. 15. № 1. P. 76-88.
3. GLONASS. Principy postroenija i funkcionirovanija. Izd. 4-e / Pod red. A.I. Perova, V.N. KHarisova. M.: Radiotekhnika. 2010.
4. Gabriel W.F. Adaptive arrays - An introduction // Proc. IEEE. 1976. V. 64. № 2. P. 239-272.
5. Pistolkors A.A. O raschete perekhodnogo processa v adaptivnojj antennojj reshetke // Antenny. 1980. Vyp. 28. S. 13-26.
6. Monzingo R.A., Miller T.U. Adaptivnye antennye reshetki: Vvedenie v teoriju / Per. s angl. pod red. V.A. Leksachenko. M.: Radio i svjaz. 1986.