| With better performance in programmability, versatility and portability, Digital Array Radar (DAR) should be the development trend of the radar in the future. As an important technology of DAR, Digital beamforming (DBF) can greatly improve DAR’s capability of anti-jamming. In current, lots of matured researchs have been done on receive DBF, however there is still much research to be done on transmit DBF.About the research of transmit DBF algorithms, two sections are studied in this paper. The first section is about Digital Multi-beamforming (DMBF) algorithm. Firstly, three transmit DMBF are studied:Digital Phase Configuration algorithm, Invert Fast Fourier Transform algorithm and Orthogonal Projection algorithm. Secondly, a low sidelobe LCMV algorithm is studied for the shortcoming of the three algorithms, namely that they can not simultaneously realize null control and low sidelobe, and furthermore a robust low sidelobe LCMV algorithm is studied. The second section is about cosecant-squared pattern (CSP) synthesis algorithm. A pattern synthesis algorithm based on Convex Optimization and Spectral Factorization is studied. Compared with the performance of Particle Swarm Optimization using Matlab, the studied algorithm gets lower sidelobe level and ripple amplitude, showing its great value in the apply of pattern synthesis.About the launch of the transmit DBF platform, this dissertation designs a 16 channels transmit DBF board. At first devices are selected by the hardware requirements of the system, then the schematic and PCB of the hardware system are designed and finally the main devices are tested. Besides, a method based on m/WH mixed codes for calibrating amplitude and phase errors among transmitting chanals is proposed. Simulation results show that at high SNR this algorithm can effectively compensate for different amplitude and phase errors, proving the effectiveness of this algorithm in the calibration of amplitude and phase errors among transmitting chanals. |
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