The method of forming “zeros” of the adaptive antenna array directive pattern for mobile radiation sources

Functioning of radio engineering systems in modern conditions is associated with the need to ensure the electromagnetic compatibility of radio electronic facilities and the fight against natural and intentional interference. There are various approaches to fulfill these requirements, such as temporal, frequency, code division of signals and their combinations, as well as methods of noise-immune coding. Such approaches so far make it possible to ensure the required electromagnetic compatibility of radio electronic means and to deal with interference. However, in connection with increasing opportunities for intentional interference organization, these methods in the future will not ensure the immunity of radio electronic means to the full.

One of the possible directions to ensure noise immunity of radio electronic means is using of an antenna array as a transmittingreceiving antenna. The main advantages of this type of antenna are the possibility of forming a narrow-beam directional pattern and the ability to withstand interference.

The most promising direction of ensuring noise immunity of radio-electronic means is implementation of adaptation methods in antenna arrays. However, the question of adjusting weight coefficients for the case of a permanent change in the location of radiation sources is still open.

The article is devoted to the development of the method of forming a vector of weight coefficients that provide the required directional pattern of the adaptive antenna array in real time for mobile radiation sources.

As a criterion of adaptation, the criterion of the maximum signal/(noise + noise) ratio is taken in the article. To achieve the maximum signal/(interference + noise) ratio, it is necessary to find the optimal vector of weight coefficients. However, in the case where the sources of interference signals are in motion, the effectiveness of methods for finding the optimal weight vector associated with the direct inversion of the covariance matrix of the interference signals is low. This is due to the fact that for each change in the angular position of the source of the interference signals, it is necessary to perform the operation of reversing the covariance matrix of the interference signals, which occupies a sufficiently large time interval.

To solve the problem in the paper, it is proposed to use the iterative method of gradient descent, which makes it possible to form a vector of weight coefficients in a finite number of steps which is close to optimal, but without realizing the operation of direct inversion of the covariance matrix of the interference signals. However, the known literature describes the application of this method for stationary conditions without taking into account movement of sources of interference signals in space.

In the article, it is proposed to adjust the weighting factor vector taking into account the value of the weighting factors vector at the previous angular position of the sources of the interference signals. This approach allows to significantly reduce the time of the transient process and to ensure formation of "zeros" of the directional pattern of the adaptive antenna array for the case when the sources of interference signals are in motion.

The results of the numerical simulation, given in the article, have confirmed the derived regularities.