Modelling the EM properties of dipole reflections with application to uniform chaff clouds

[摘要] ENGLISH ABSTRACT: The origin of chaff dates as far back as WWII, acting as a passive EM countermeasure it was used to confuse enemy radar systems and is still in use today. The purpose of this study is, firstly, to build up a knowledge base for determining chaff parameters and secondly, to calculate the theoretical Radar Cross Section (RCS) of a chaff cloud.Initially dipole resonant properties are investigated relative to dipole physical dimensions. This is extended to the wideband spatial average RCS of a dipole with application to chaff clouds. A model is developed for calculating the theoretical RCS of a cloud typically produced by a single, multiband chaff cartridge.This model is developed on the principles of sparse clouds with negligible coupling; the dipole density for which the model is valid is determined through the statistical simulation of chaff clouds.To determine the effectiveness of chaff clouds, the E-field behaviour through a chaff cloud is investigated numerically. From simulation results a model is developed for estimating the position and drop in E-field strength. It is concluded that though it would be possible to hide a target behind a chaff cloud given ideal circumstances, it is not practical in reality. Given the presented results, recommendations are made for future work.

[发布机构] Stellenbosch University