Synthetic Aperture Imaging of Multiple Point Targets in Rician Fading Media

This paper presents a study of stability, resolution, and detection for broad-band synthetic aperture (SA) imaging in Rician fading media. The stability condition $BNK^2/(K+1)\gg M$ is derived, where $K$ is the Rician factor, $B$ is the effective number of coherence bands, $N$ is the effective number of array elements, and $M$ is the number of (widely separated) targets. The imaging method is tested numerically with randomly distributed discrete scatterers, and comparisons with the imaging with the full response matrix (RM) are made. The resolution study reveals several interesting effects: First, given the same measurement resources, SA imaging has better resolution performance, although less stable, than RM imaging; second, for both imaging methods, the cross-range resolution measure (i.e., “full width at half maximum”) decreases with the aperture ($N$ fixed) and the probe spacing (the total aperture fixed) while the range resolution increases with both parameters. A statistical scheme is introduced to reduce the uncertainty when the stability regime is not realized.