Study On Adaptive Beamforming And Interference Suppression Of Phased Array

In recent years, with the rapid development of computer technology and the signal processing technology, phased array radar got more and more application and development, and array signal processing becomes an important branch of signal processing. Mainly includes Adaptive Digital Beamforming (ADBF) and Direction of Arrival (DOA) estimation. ADBF can effectively keep the expected Signal and filter the jamming Signal, in order to achieve the optimal output SINR. A large phased-array always consist of thousands of elements, the hardware costs and the amount of calculation are quite huge if we use element level processing, so we should pay much more attention to ADBF at subarray level. Direct subarray weighting (DSW) structure and generalized sidelobe cancellation (GSC) structure are two typical ADBF method at subarray level and what we will study in this thesis.The algorithms based on the two typical ADBF structure at subarray level are given detailed research in this thesis, and give the performance analysis of the two kinds of structure under the condition of limited word length. And then we will study the performance of a subarray division based on randomly sampled method.Firstly, several realized algorithms based on DSW structure and GSC structure at the subarray level are given out. Then the parameter of the combining method based on DSW structure at subarray level will be analyzed, through the simulation results we will give the parameter selection result which can make a lower side-lobe while not introducing too much loss of output SINR. And of all above algorithms were discussed in limited words length, by comparing the performance of these algorithms we can give the robust adaptive algorithm, which prowides important reference basis for the engineering application of ADBF.Scecondly we discuss full digital weighting at subarray level using genetic algorithm (GA) instead of simulation weighting at element level to reduce side-lobe both in sum and difference beam, the simulation result verify its validity.Finally studied a method to divide the full array into independent subarrays where each subarray spans most of the full array aperture. Individual subarrays contribute to the combined output and can be realized in a modular fashion. The performance of the subarray adaptive beamformer is shown close to that of the full array for a small number of interferences.