Polarization-Aware Ray-Tracing Enhanced Back-Projection Algorithm for Microwave Imaging in Complex Multipath Environments

TL;DR

This paper introduces a polarization-aware ray-tracing enhanced back-projection algorithm for microwave imaging that improves target detection and resolution in complex multipath environments by leveraging reflected paths and electromagnetic polarization.

Contribution

The method integrates ray-tracing with back-projection, considering electromagnetic polarization, to enable imaging of hidden targets and enhance resolution without additional measurements.

Findings

Improved imaging of hidden targets using reflected paths.

Enhanced resolution by virtually increasing aperture size.

Incorporation of polarization-dependent phase compensation.

Abstract

A ray-tracing (RT) enhanced back-projection algorithm (RT-BPA) for microwave imaging in multipath environments is presented. By tightly incorporating the concept of ray-tracing into a generalized version of traditional BPA, this method ensures improved image quality by addressing two important issues. First, when the line-of-sight (LOS) path is obstructed, reflected paths, if available, enable imaging of hidden targets, which extends the applicability of the standard BPA beyond its normal use case. Second, the consideration of reflected ray-paths is equivalent to virtually increasing the aperture size, thus, improving image resolution without requiring new measurements. A key factor in achieving these advancements is the consideration of the vector nature of electromagnetic waves with polarization-dependent phase compensation, which is often ignored when employing a scalar-wave based formulation of the electromagnetic vector field. In addition, the presented method employs a shooting and bouncing rays (SBR) framework, offering better flexibility compared to manual path evaluation in existing RT-BPAs.