Optimizition Of MIMO Array Configuration For UWB Vitual Aperture Imaging Radar

Combined with multiple-input multiple-output (MIMO) arrays, the ultra-wideband(UWB) virtual aperture radar systems can offer images with high resolution capabilityfor target detection, discrimination and recognition. With the advantages of real-time,safe, reliable, and cost-efficient imaging sensors, it is of great value for through-the-wallradar imaging, subsurface imaging, security surveillance at public settings, and medicalimaging.In UWB virtual aperture radar imaging systems, the configuration of the arrays is akey issue, and it has great effects on imaging quality, parameters estimation and targetsdetection. The transmit and receive arrays within MIMO determine the spatial samplecapability together, and the virtual array elements offer abundant sample data. Thus theimaging performance such as resolution and sidelobe level is affected by theconfiguration, and the radar could achieve more information about the target. What’smore, the proper array design is helpful to simplify system structure and signalprocessing.This thesis analyses the character of UWB MIMO array imaging, and discusses therelationship between resolution, sidelobes and grating lobes. The point spread function(PSF) is derived both in space-time and space spectrum domain, consequently, thespace spectrum supporting region and its corresponding PSF is researched. On the basisof this analysis, point target oriented array configuration optimization is researched, anda coarray based MIMO array design method is addressed, which satisfies the imagingguideline such as resolution and grating lobe level. Moreover, particle swarmoptimization (PSO) is used to determine the optimal antenna array topology. In order tosurppress the sidelobes and grating lobes in the images, the non-orthogonal sidelobesreduction method for UWB virtual aperture radar is proposed, and a realization ofsidelobe/grating lobe reduction by CLEAN technique is successfully applied. Inaddition to point target oriented optimization, the array could also be configured bymaximize the information according to the scattering character of the target. This thesisderives the optimal array configuration based on signal noise ratio (SNR) and mutualinformation (MI) optimization. The configuration is simulated with noise and clutter,and the optimized one raises the SNR or MI. what’s more, space spectrum amplitudeoptimization is studied based on maximum SNR and MI criterion.