A Method of Moments Solution for Wires Inside a Reverberation Chamber using Spectral Domain Techniques

Licentiatavhandling, 2005

This thesis describes a method of moment code that can be used for analyzing PEC objects in a reverberation chamber. A major part of the thesis deals with the derivation of an efficient Green¡¯s functions for a PEC cavity in general and a reverberation chamber in particular. Appended to the thesis is a collection of papers produced during the development of this code. A reverberation chamber is a test facility which for many years has been used for EMC-testing and nowadays also for antenna measurements. Basically, a reverberation chamber is a 3D resonant metallic cavity in which the electromagnetic modes are stirred to provide a Rayleigh fading environment that is statistically isotropic and repeatable and has similarities with a uniform multipath environment in mobile communications. In order to perform accurate measurements in the reverberation chamber the key is efficient mode stirring. Several different stirring techniques can be used, and a convenient way to study these techniques is to perform computer simulations. We have developed a method of moments code that can analyze PEC (perfect electric conductor) objects in a reverberation chamber. The Green¡¯s function for the reverberation chamber is constructed by using planar wave spectral domain techniques as implemented in G1DMULT and imaging combined with periodic boundary conditions. In this thesis we describe the code including four ways of improving the performance of the computation of the cavity Green¡¯s function: analytic expressions for currents on boundaries, asymptote extraction, limiting the number of necessary modes and rotation of the coordinate system. Moreover, several validation cases based on comparisons with measurements as well as other computer codes are presented.