Bistatic 3D SAR for wall parameter extraction in cluttered environments

Abstract

Abstract Through‐wall radar is an emergent technology rooted in urban surveillance, a key component being synthetic aperture radar (SAR). Accurate through‐wall SAR relies on knowledge of the refractive index and thickness of any obscuring walls. Such information is rarely known beforehand and is subject to change on a sample‐by‐sample basis. It is therefore necessary to obtain the material properties in conjunction with any SAR measurement. In this letter, a remote data‐driven asymmetric bistatic SAR approach is taken by means of matching the range to the direct back face reflection with an explicit geometry‐based model. The proposed method relies on an accurate knowledge of the bistatic measurement geometry. Using the bright reflection from the front face of the wall, a method for refining an estimate of the bistatic measurement geometry is proposed. This approach is extended to three‐dimensions to improve usability in heavily cluttered environments. This method is empirically validated using three‐dimensional SAR measurements of both a wall‐only, and a heavily cluttered scene. The method is shown to accurately extract both the refractive index and thickness of a concrete wall, with both measurements in agreement with each other and an independent validation measurement.

Keywords

• Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research
• Interpolation and function approximation (numerical analysis)
• Optical, image and video signal processing
• Radar equipment, systems and applications
• Geophysical techniques and equipment