Image Theory Verification: Closed Metal Loops in Proximity to Finite-Size Radiators and Grounds

Abstract

With the use of a closed metal loop, a recent study proposed a methodology to analytically predict and further approximate the electromagnetic field (EMF) distribution and strength of an emitting printed circuit board, even at very large distances. The basic idea was based on small loop theory together with the existence of generated artificial sources due to mirrored image loops. This paper focuses on image theory verification using full-wave simulations, providing a detailed analysis of the produced equivalent image sources due to finite-size radiators and grounds. This study clearly highlights the reasoning behind that methodology, particularly how image theory should also be reapplied to conventional image sources, which was not explicitly elaborated in a previous paper. That makes it possible to use the analytical formulations of a loop in free space to approximate EMFs in the presence of finite size radiating conductors. For example, in automotive compliance testing where a minimum test distance of 1 m up to 10 m is required, it can avoid using costly practical setups or computationally intensive full-wave simulations.