Hybrid Cartesian/unstructured numerical method for efficient evaluation of scattered fields: Application to buried object detection from airborne platforms

This paper focuses on the study and development of an efficient numerical method designed to simulate the radar cross section (RCS) of objects buried in lossy ground and illuminated by a plane wave. The primary objective aligns with the overarching challenge of detecting buried targets in the ground using an airborne radar system. In this scenario, a source antenna illuminates a considered 3D domain, and sensors receive the scattered field from the targets. To enable accurate and efficient simulations, the proposed tool utilizes a Cartesian/unstructured mesh and employs hybrid method that combines two finite volume solvers. In the contents of the paper, we first present a strategy for obtaining Cartesian/unstructured meshes. Subsequently, we study the hybridization of two specific finite volume schemes. Additionaly, a ground and a Near- to Far-field model are introduced for buried targets. To validate and showcase the advantages of our hybrid approach, practical examples are presented. Finally, the strategy designed for handling meshes composed of multiple Cartesian and unstructured zones is detailed.