| Digital beamforming(DBF) is a combined product of the antenna beamforming theory and digital signal processing technology. DBF technology takes full advantages of the information of antenna array spatial to make beam have the performance of supur-resolution and low sidelobe lever, achieving scanning beam, tracking target and so on.Direct Digital Synthesis(DDS) is a digitalized method of frequency synthesis. In the launch-DBF system of DDS-based, DDS technology can achieve the phase and amplitude weighted. There are many advantages for using DDS to generate signal and control amplitude and phase:scanning beam will be faster, beam will be more flexible controlled; signal amplitude can be precisely and rapidly adjusted, achieving low sidelobe performance easily; DDS can calibrate amplitude and phase without other calibration module.In this paper, the launch-DBF antenna system, the principle of the antenna array and basic characteristics were analyzed.Taylor weighted is widely used in engineering of low sidelobe diameter distribution. The numerical method of Taylor distribution and the sidelobe characteristics of the Taylor disturbution were analyzed, and a program of low sidelobe antenna was designed.In this paper, Amplitude and phase errors, mutual coupling effects on antenna array were studied. A calibration program for the launch-DBF system of DDS-based was proposed. At last, DDS was studied and the signal generator by both the DDS chip and FPGA-based were designed. Finally, one-channel signal generator was achieved and four-channel signal generator controlled by FPGA was designed. |
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