A Generalized Finite Sized Dipole Model for Radar and Medical Imaging Part I: Near Field Formulation for Radar Imaging - Abstract *

Abstract

This paper presents an electric dipole-based formulation for near-electromagnetic field radar imaging, and the development of an algorithm to perform correct image reconstruction in the near-field region. Synthetic Aperture Radar (SAR) imaging is a Radar imaging concept that is used to obtain high resolution. Signals are transmitted as electromagnetic waves and by appropriate processing of the reflected radar signals, images are obtained. It is usually assumed that the electromagnetic signals involved are the far fields with no variation in magnitude with distance. The SAR concept is also used in laboratory set-ups to obtain Radar Cross Section (RCS) measurements. In such a situation the near electromagnetic fields are dominant and hence should be taken into account. In this paper, the radar scatterers are modeled by discrete finite sized electric dipoles. Based on this model a new signal model is proposed and the effect of the near electromagnetic fields on the SAR images is analyzed. A suitable correction process is proposed whereby imaging could be carried out at in the near field region of the electromagnetic signals.