MIMO-SAR Waveform Design Based On The Multi-dimensional Diversity

Multiple-input multiple-output synthetic aperture radar(MIMO-SAR)provides more degrees of freedom than the traditional SAR and offers dramatic improvements in imaging performance,such as high-resolution wide-swaths,three-dimensional imaging,and multi-baseline interferometry.Waveform design for multiple transmitters is one of the most important and challenging issues in MIMO-SAR systems.Based on the framework of multidimensional diversity,the theory of waveform design for MIMO-SAR and key technology of the MIMO-SAR system is studied.The main contribution of the dissertation is summarized as follows:(1)The logical link between SAR and MIMO-SAR and the sequential analysis of the traditional MIMO-SAR of waveform imaging performance is proposed.The framework of multidimensional diversity MIMO-SAR waveform design is an operator perspective,which deconstructs the waveform design for MIMO-SAR in the mathematical essence.(2)Joint time-frequency analysis of non-stationary signals analysis as a powerful tool for performance analysis of MIMO-SAR signal,it can get more physical analysis results.Based on time-frequency analysis,waveform design for MIMO-SAR research,developed a comprehensive integral side lobes than the signal in the frequency domain analysis of more general mathematical models.Through this model,this paper shows that between the time and frequency domain signal with the common support set cannot be orthonormal under the inner product operator.MIMO-SAR stated dimensions for time and distance to delay(angle in range),multidimensional point sets for window convolution operator selected algorithms.(3)A new space-time coding(STC)scheme for multiple-input multiple-output synthetic aperture radar systems is proposed in this paper.In the new scheme,two successive signal periods are put into one transmit duration to minimize the time-variant channel effect.The even and odd components of the transmitted waveforms are modulated into distinct Doppler frequencies in the azimuth direction and can be separated by bandpass filter in the range-Doppler domain.The presented STC scheme can suppress the interchannel ambiguous energy caused by the time-variant channel responses,which typically occur in conventional STC schemes,and increase the signal-to-noise ratio(SNR)of the echoes by a decoding matrix.To further suppress the interference,a waveform called time and frequency comb-like chirp(TFCC)is proposed.With the application of the complementary comb-like structure in the time and frequency domains,two TFCC waveforms are short-term shift-orthogonal(STSO)and constant envelope.Moreover,these corresponding TFCC waveforms can share the same antenna and time gate without sacrificing any TFCC waveforms' peak level.(4)This article also introduced thecextensions based on framework of multidimensional diversity for MIMO-SAR system,including DPCA technical theory and analysis,echo generation based on electromagnetic simulation,integrated waveform design based on time-frequency analysis.