Band-Limited Reconstructions in Microwave Imaging

摘要

Illuminating-signal bandwidth determines the resolution of depth imaging. This is principally independent of the location of the frequency band occupied by this signal. In this contribution illuminating baseband signals, whose spectra include all frequency components from a certain upper limit down to zero (DC), are compared to the technically more feasible passband ones, with both lower and upper frequency limits. It is shown that only the former are capable of depth-image reconstruction of arbitrary variations of the imaged material property (e.g. permittivity in Microwave Imaging). On the other hand, passband illuminations are suitable for reconstructing images with abrupt, or at least very sharp, changes in the imaged material property. Fine slow variations between such abrupt changes cannot be accurately captured in this case. This paper is conceptual and essentially of a fundamental nature. Therefore neither simulations nor measurements are included.