1 research outputs found
Bistatic SAR for Building Wall Material Characterisation
© Cranfield University 2020. All rights reserved. No part of this
publication may be reproduced without the written permission of the
copyright ownerThis thesis addresses the problem of using radar to extract interpretable information
concerning both the structure and electrical properties of a wall, and the environment
behind it. This is broken down into two subproblems: how to determine the thickness and
electromagnetic properties of the wall without being in direct contact with it, and how to
obtain the most accurate images of what lies beyond the wall.
Existing research in the area is evaluated and a theoretical study is presented on the use
of monostatic, bistatic, and multistatic Synthetic Aperture Radar (SAR) in both one and
two dimensional apertures. New methods of determining the wall properties are evaluated
by both computer simulation and with laboratory radar measurements, where a wall of
concrete blocks is constructed. The robustness of the asymmetric SAR geometry
approach is evaluated with the addition of complex objects placed behind the wall. The
uncertainty associated with estimating the wall properties is evaluated and consequential
improvements to image quality are discussed.
It was found that an asymmetric bistatic SAR geometry accurately extracts the refractive
index and thickness of a wall. The method is applicable to both cluttered environments
and non-parallel wall trajectories without loss of accuracy. Applying a compensation for
refraction in the SAR imagery results in better positional accuracy but does not
necessarily result in better image focusing. Volumetric multistatic image formation
benefits from applied refraction compensation. SAR image formation, and in particular
volumetric image formation, can be significantly accelerated via a spatially variant
basebanding technique followed by zero padding. Spatially variant basebanding is sub optimal when applied to a Through-Wall radar scenario where there is a visible wall
signature in the image.
Keywords:
Through-Wall radar, Multistatic radar, Multidimensional signal processing,
Electromagnetic propagation, Radar imagi