Reseach On Subarray Configuration And Digital Beam Forming Methods For Planar Phased Array Radar

With the rapid development of Digital Beam Forming(DBF) technology, phased array radar has been provided with significant advantages in coping with increasingly complex electromagnetic environment. General y, a planar array consists of hundreds and thousands of elements. Thus in practical use the array elements are grouped into subarrays in order to downsize the system and lower the cost of hardware and software. Consequently, DBF algorithms are applied at subarray level.The differences in subarray configurations have significant impact on the performance of beam patterns. However, there is no general solution which is suitable for all kinds of radar applications. Additionally, low sidelobe is often required to guarantee the performance against non-stationary cluster or reverberation. Therefore, this thesis focuses on subarray configuration of planar array and sidelobe suppression for adaptive beamforming. The main content and innovation of this thesis are listed as follows:1. Research on three already existed subarray configuration methods was done and corresponding MATLAB simulation results were presented. Besides, Genetic algorithm(GA) was employed to optimize the subarray configuration of a two dimensional rectangular grid array. Simulations showed that the optimized subarray configuration performed much better in sum and difference beam forming.2. Several classical and frequently used algorithms of sidelobe control for quiescent beam pattern were studied. Their implementations on uniform linear array(ULA) and circular grid array were done via MATLAB simulations.3. ADBF algorithms were classified into three categories for analysis and comparison. 1) Iteration based LMS algorithm. 2) Inversion of sampling matrix based algorithms. 3) Interference subspace based algorithms. Detailed analysis was attached to the reasons of sidelobe rising and jitter. Besides, solutions to sidelobe control in ADBF were proposed and were verified with simulation results.4. A new convex optimization based approach for sidelobe suppression in ADBF at subarray level was proposed. Compared with penalty function method, which is relatively superior to other kindred methods, simulations showed that for auniform linear array, the proposed method could suppress sidelobe level considerably, especially lobes close to mainlobe. Furthermore, it was able to produce better shaped mainlobe which was extremely closed to the referenced pattern.