Analysis And Design Of UAV-borne SAR Receiving System

The paper has introduced the status of UAV-borne SAR,briefly analyzed the principle of SAR imaging, introduced the work principle and composition of the receiving system, introduced and analyzed the stepped-frequency and the stepped-chirp used in broadband waveform synthesis, the dechirp processing used in receiver.According to the characteristics of UAV platform, analyzed and compared several kinds of the broadband waveform synthesizer and the receiver program, designed the framework of the receiving system and then designed and calculated the performance parameters of the receiving system, such as phase noise, receiving gain, noise figure. The paper has introduced the design of the broadband waveform generator, presented a synchronous clock driver circuit design, which can effectively ensure the two DDS chips to synchronize in the condition of high speed clock. Furthermore, the compensation of magnitude-phase distortion in broadband system has been discussed, aimed at the harsh environmental conditions of UAV, such as the Vibration resistant of the frequency Synthesizer, the thermal adaptability and the electromagnetic compatibility have also been discussed in the paper.The test results of the receiving system and the imaging result of the flight test shows that the receiving system has good performance, meet design requirements and receiving system could reliably operate in harsh environments. The waveform generator designed in the paper could output broadband waveform, the center frequency of the waveform could be flexibly chosen, wherefore it has high value of engineering application. Finally, the development prospect of UAV-borne SAR is discussed in the paper.