S.N. Lysenko - Head of Sector, FSUE «RNIIRS» (Rostov-on-Don) B.D. Manuilov - Dr. Sc. (Eng.), Professor, Leading Research Scientist, FSUE «RNIIRS» (Rostov-on-Don) E-mail: b.d.manuilov@mail.ru A.Yu. Padiy - Engineer, FSUE «RNIIRS» (Rostov-on-Don) E-mail: a.padiy@list.ru

The goal of the paper is additional reduction of the interference penetrating into the intermediate frequency channel through the receive image channel of active phased antenna array for the case of the inefficient interference suppression by means of hardware methods. To achieve the assigned goal the following tasks are solved: (1) the design of the methods for the spatial suppression of image channel frequency by means of antenna array, (2) the evaluation of designed methods efficiency in the case of their implementation in the linear active phased antenna arrays, (3) the evaluation of the proposed methods applicability to the multi-element active phased antenna array with the nonrectangular aperture. The suggested methods for the spatial interference suppression on the image frequency are based on the maximization of the functional that characterizes the signal to noise ratio (SNR) at the receiver input in the case of the impact of interference on the image frequency. According to the first method the functional numerator is the sum of the power of signal spectral components within the frequency band Δω of the main receive channel for the main beam direction. The denominator is the sum of the noise and interference power calculated over the entire space of real angles within the frequency bands of basic channel Δω and image channel Δωimg. In the second method the nominator of the signal to noise ratio is the square of the sum of the spectral component amplitudes. The denominator for this method is the same as for the first method. The efficiency evaluation of the suggested methods is performed for linear and multi-element active phased antenna array with non-rectangular aperture. In the examples under consideration the image frequency is higher than frequency of the main channel at 8% and the operational frequency band is 1%. The numerical experiment results show that the proposed methods have similar results and ones allow to suppress the interference on the image frequency by 30 dB. The second method is preferable since it allows analytical calculation of the complex current amplitudes of the array elements. At this paper the problem of deformation and displacement of the main beam is solved by introducing the fictitious interference. Thus, the paper shows the use of the proposed methods to the nonrectangular aperture multi-element active phased antenna array is possible by subdividing the array into the non-identical subarrays. The proposed methods are suitable for the active phased antenna arrays with amplitude and phase control as well as for the digital antenna arrays.

 

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