Near-Field Focusing Operators for Planar Multi-Static Microwave Imaging Using Back-Projection in the Spatial Domain

TL;DR

This paper introduces an improved back-projection imaging method for planar multi-static microwave imaging, which enhances image quality by applying magnitude correction factors and artifact suppression based on a plane-wave expansion approach.

Contribution

The paper derives new focusing operators with magnitude correction factors for better microwave image reconstruction in near-field scenarios, improving upon traditional phase-only compensation methods.

Findings

Enhanced image quality with artifact suppression.

Validated improvements through simulated and measured data.

Applicable to near-field multi-static microwave imaging.

Abstract

Based on a plane-wave expansion of the observation data in quasi-planar multi-static scattering scenarios, an improved formalism for image creation utilizing back-projection in the spatial domain is derived. The underlying integral expressions for different focusing operators are derived analytically leading to magnitude correction factors, which are mostly relevant for reconstructing microwave images when the distance from the scattering object to the aperture plane is small. It is shown that the derived imaging procedure is superior to the traditional back-projection only compensating the phase delay of the measurement signals and validate our findings based on simulated as well as measured data. Since the derived focusing operators correspond to a low-pass filtering of the spatial images, the resulting modified multi-static back-projection algorithms effectively suppress imaging artifacts as well.