SAR measurement simulation on urban structures using a FDTD technique

The purpose of this work is, starting from a close tracking of basic electromagnetic processes, to propose a simulator enabling a better understanding of the radar images of urban areas. An improved understanding of the radar images formation processes in this case should lead to a better knowledge of the potentialities of the SAR imagery of urban areas. With the rapid development of computer, numerical techniques with no physical approximation play more and more important role in some studies such as electromagnetic scattering from urban scene. We argue that finite-difference time domain method (FDTD) is a quite new and promising approach for the propagation in urban areas. In order to numerically evaluate its electromagnetic return to an active microwave sensor, a geometric and electromagnetic model of a typical element of urban structure is presented. It consists of a rectangular parallelepiped whose vertical walls form a generic angle with respect to the sensor line of flight. This parallelepiped is placed on an either smooth or rough surface, to take into account multiple scattering between buildings and terrain. Finally, the above model is used to analyze the field backscattered from a building, as a function of the main scene parameters.