A Study On Pattern Synthesis Algorithms Based On Adaptive Array Theory

Array antennas are widely used in radio systems such as radar,communications,and navigation,etc.In some specific applications,the array antenna needs to be designed to meet the requirements on the pattern shape and some performance metrics such as gain,beamwidth,and sidelobe level.Array pattern synthesis(APS),which produces the desired pattern response by tapering the array,is one of the critical techniques in the design of array antennas.An effective APS approach is based on the adaptive array theory by injecting virtual interferences in the angular area to be controlled.However,the selection of virtual interference powers in the existing methods is mostly based on the trial and error method,which leads to inaccurate control of the array pattern.In this regard,this thesis studies a pattern synthesis method based on the adaptive array theory by iteratively injecting virtual interferences with specific power values,so that the array pattern response is gradually approaching the expected one and can be controlled more flexibly,conveniently,and more accurately.The main accomplishments and innovations are summarized as follows.(1)Proposed and developed a single-point array response control algorithm with maximum gain(SPARC-MG)to solve the problems in traditional adaptive methods that the virtual interference powers are difficult to be determined and the pattern response cannot be controlled flexibly and accurately.This algorithm can reach the precise control of the singlepoint pattern level through an iterative procedure,where the response values in different directions are controlled accurately one-by-one.This algorithm breaks through the traditional idea of overall design pattern by using the concept of single-point precise control combined with iterative algorithm to realize the overall precise control of pattern response,and is easy to implement in practical applications.(2)Extended the above SPARC-MG algorithm to a multi-point array response control algorithm with maximum gain(MPARC-MG)by considering the simultaneous control of the pattern response at multiple points.This algorithm effectively reduces the number of the iterative cycles,greatly saves running time,and realizes the rapid synthesis of the pattern,which makes the algorithm be potentially useful for the pattern synthesis of large-scale arrays.(3)Proposed a single-point array response control algorithm with minimum deviation(SPARC-MD)to improve the accuracy of parameters optimized using geometric methods in the above SPARC-MG algorithm.This algorithm can accurately calculate the power value of virtual interference through a general analytical model for the algorithm parameters.The SPARC-MD algorithm can be used to synthesize the array patterns with various characteristics such as flat main lobe,deep notch,and low side lobes,etc.and has been verified by using measured data of element patterns,which provides a new way to improve the robustness of beamforming against interferences.