Determination of radiation pattern for linear antenna array with multistage adaptive compensator of interferences

Introduction. Adaptive compensation algorithms of interference in digital antenna array (DAA) are characterized by high computational complexity. As result, it makes it difficult to implement them in real time. A parallelization of computational processes and simultaneous processing in all parallel channels is one of the main directions of increasing the speed of processing. The approach based on block Gram-Schmidt orthogonalization makes it possible to synthesize multistage adaptive compensators of interference with parallel-sequential signal processing that similar to the architecture of multiprocessor computer systems. The signal processing in DAA based on multistage adaptive compensator of interference is more complex than in single-stage ones. Each stage has own set of weight coefficients. As result, a technique for calculating radiation pattern (RP) of a linear DAA with a multistage adaptive compensator of interference and certain architecture and parameters is required. Theoretical results. The block diagram of the adaptive compensator of interference by using block signal orthogonalization of compensation channels and consistent determination of the compensation error has a ladder form and includes some stages. Each stage consists groups of modules. Each module in the group is a multi-input weight adder. The complex signal envelope from the DAA output applies to the main channel of an adaptive compensator of interference. The technique for calculating RP of DAA with a multistage adaptive compensator of interference by using block orthogonalization of compensation channels signals includes the following steps: 1. Forming of the matrix impulse characteristics for the adaptive compensator of interference stages. 2. Calculation of the matrix impulse response for a multistage filter realizing an interference compensation procedure based on its factorized representation. 3. Determination of the weight coefficients of an equivalent single-stage adaptive compensator of interference in the form of multi-input weighted adder. 4. Calculation of the RP of DAA with an equivalent single-stage adaptive compensator of interference. Experimental results. RP analysis based on the proposed technique is carried out for six-element linear DAA with one-, two-, three- and six-stage adaptive compensators of interference and three jammers. The analysis confirms that considered adaptive compensators of interference have the same effectiveness of interference elimination. In the same time, they are characterized by the same accuracy of "zeros" formation on interference sources and the width of rejection zone for different values of correlation matrix conditioning of the interference. Conclusions. We propose the technique for calculating the RP of DAA with multi-stage adaptive compensator of interference by using the factorized representation of the matrix impulse response of a multistage filter. This compensator is based on block signals orthogonalization of compensating channels and provides parallel-sequence signal processing.