A novel non-uniform hybrid sampling technology for the high-resolution mini-SAR system

Large bandwidth is the important feature of the UAV-borne high-resolution miniature Synthetic Aperture Radar (mini-SAR), the high-speed ADC is required for receiving the wideband echoes according to Nyquist's sampling theorem. The real-time Nyquist sampling for wideband echoes with the super high-speed ADC is not most suitable because of the low quantization resolution, high cost and large power consumption. In the paper, a novel non-uniform hybrid sampling technology is proposed to receive the wideband echoes and reduce the requirement for the sampling rate of ADC. By optimizing the timing of the transmission and reception of SAR signals with the proposed non-uniform hybrid sampling technology, the ADC with a sampling rate of 300 million samples per second (MSPS) can meet the sampling requirement of the SAR echoes with a wideband of 2.0 GHz, where both the phase disturbance and side-lobes of the SAR echoes can be reduced greatly. The simulation experiment of the Ku-band SAR with a wideband of 2.0 GHz show that the level of the side-lobes of the SAR echoes can be reduced to below -14 dB, and both the range resolution and azimuth resolution are better than 0.2 m.