Modeling Error and Calibration Techniques for a Faceted Metallic Chamber for Magnetic Field Microwave Imaging

Abstract

This paper introduces and analyzes a novel 3-D microwave imaging chamber composed of a number of intersecting flat metallic facets that form a hemiellipsoid. Synthetic studies demonstrate that the faceted chamber geometry provides advantages in modeling error reduction and reconstruction quality at a greater number of frequencies than a comparable cylindrical chamber. The experimental chamber is introduced along with small magnetic field half-loop probes mounted on the chamber walls. An examination of incident and scattered field modeling errors in the faceted chamber is carried out for simple cylindrical targets in an air background. A variety of calibration and measurement techniques are compared, and the reconstructed permittivity maps are compared very well with an equivalent synthetic problem. Finally, the system is used to image a simple two-region breast phantom in air, and with the incorporation of prior information, tumor detection is shown to be possible.