MIMO SAR system using digital implemented OFDM waveforms

This paper designs a multi-input multi-output (MIMO) synthetic aperture radar (SAR) system using digital implemented orthogonal frequency division multiplexing (OFDM) waveforms, which can not only avoid ambiguous energy caused by the nonideal orthogonality of current-taken MIMO SAR waveforms, but also reduce the pulse repetition frequency (PRF) by a factor of 2N_l -1, where l N denotes the number of subapertures. One linearly frequency modulated (LFM) signal sampled in frequency domain is modulated into the odd subcarrier frequencies of OFDM waveforms, and another as the weights of even subcarrier frequencies. In order to avoid aliasing in time domain caused by extracting the weights of subcarrier frequencies, the sliding discrete Fourier transform (SDFT) is used for demodulation. The procedure of MIMO-OFDM SAR imaging is detailed. Theoretical analysis and simulation results illustrate the feasibility of this system.