OBJECTS CHARACTERIZATION BY MEANS OF WIDEBAND SIGNALS

Abstract

Thesis deals with objects characterization by means of wideband signals. More speci cally, radar cross section and high-resolution images are used to describe scattering behavior of objects in wide frequency band. The aim of this thesis is then to develop a simple method allowing to predict accurate far eld radar cross section of objects from their near eld measurements and subsequently calculate high-resolution images of their contours. According to these facts, appropriate techniques are investigated and thoroughly described. Circular near- eld to far- eld radar cross section prediction technique is selected to correct data obtained from mono-static, near eld measurement of scattered eld of selected electrically large objects. One-plane measurements are undertaken in full anechoic chamber at frequencies ranging from 3 GHz to 18 GHz. Obtained results are then compared to simulated values and discussed. Since test antenna introduces tapering errors into measured radar cross section values, its broadband radiation patterns are computed employing novel antenna impulse response measurement technique. Radiation pattern correction is subsequently employed in proposed overall computational method. Obtained results show good correspondence with simulated patterns. In order to verify its applicability in image processing, images of selected objects are created by means of inverse synthetic aperture radar technique. Following achieved results, presented overall correction scheme is proven to be suitable for both, radar cross section calculation as well for restoring contour of object shape in image domain.