Modulating multicarriers with chirp for MIMO-SAR waveform diversity design

In multiple-input multiple-output synthetic aperture radar (MIMO-SAR), the orthogonal waveform diversity design plays a critical role. In this paper, we design multiple orthogonal waveforms by applying the multiple subcarrier technique in digital communications to commonly-used chirp radar waveform with large time-bandwidth product and constant modulus, so that the orthogonality of subcarriers within a common frequency band and good properties of chirp waveform are sufficiently exploited. The detailed modulation and demodulation methods are presented and the application potentials of the new waveform in MIMO-SAR are investigated. The proposed waveform diversity design method has the advantages of implementation simplicity and easy integration with the conventional SAR processor. Semi-physical simulation with an Agilent arbitrary waveform generator (AWG) and a high-speed oscilloscope (OSC) verifies the scheme. The performance is also evaluated by theoretical analysis and simulation results.