Study On Adapitve Beamforming Of Phased Array Main Channel And Guard Channel

Adaptive digital beamforming (ADBF) is an important mission of phased arraysignal processing, which make the beam mainlobe align useful signal of the desired,and generate zero trap in the direction of interference, so as to increase signal tointerference plus noise ratio (SINR) effectively. In practice large phased array usuallycontains thousands of antenna elements, and the use of array processing at elementlevel result in huge computation and hardware costs. Therefore, it has importanttheoretical significance and application value to study phased array adaptivebeamforming methods at subarray level.In this paper, by adopting sidelobe blanking system in order to improve anti-jamming capability of the phased array, the main channel and guard channel adaptivebeamforming in this system is studied intensively.Analysis is based on the direct subarray level weighted (DSW) structure of themain channel conventional ADBF method, and on its basis research approachs of thenormalization method, the mismatched optimal detector method, the subspaceprojection method and the conventional method combined with mismatched optimaldetector method which have the ability of the pattern control. Simulation proved thatthese methods achieve better adaptive performance in ideal array.For the problems existing in the actual array such as the amplitude and phaseerrors, we specially investigate the the main channel conventional ADBF methodground on generalized sidelobe cancellation (GSLC) structure. Further studies onstrictly orthogonal blocking matrix method by using Householder transformation,and discussing with grading weighted method as a new pattern control method.Simulation results show that the robustness of the system increased greatly by ADBFmethods on this structure.To avoid wave path-difference and scale down false alarm rate, based on themain channel ADBF methods, we present a new guard channel beamforming method by its subarray output, the simulation pattern of guard channel envelope cardattached to the main channel pattern above its sidelobe. This method provides thetheoretical basis for the setting threshold of the constant false alarm rate (CFAR)detect.This paper provides the theoretical principle and experimental evidence foroptimizing the technology of adaptive beamforming, enhancing the robustness andinterference immunity of the system, the proposed of the guard channel is significantfor the ADBF technology combined with target detection in the future.