PHASE UNWRAPPING IN THE PRESENCE OF SCATTERING NULLS AND APPLICATIONS TO MICROWAVE IMAGING

摘要

Utilization of our log-magnitude/phase form (LMPF) iterative reconstruction algorithm for microwave tomographic imaging has proven to be significantly more advantageous than the traditional complex form algorithm both in terms of solution convergence stability and the elimination of the need for a priori information in cases of large, high contrast imaging targets. However, for certain high contrast targets, the forward solution can often contain scattering nulls which complicate the phase unwrapping process necessary in the LMPF algorithm and ultimately can cause instability in the convergence behavior. We have developed a strategy for coping with these scattering nulls during the unwrapping process based on a theoretical understanding of their behavior. The image quality improvement is substantial compared with previous strategies.