Investigation of a raymode representation of the Green's function in a rectangular cavity
Abstract
It is known that a pointsource excited field in a rectangular cavity can be represented either in terms of summation of modes or in terms of rays produced by the equivalent image sources. Both representations involve series that are slowly convergent, so computation of fields inside the cavity is difficult. To obtain a numerically efficient scheme, a hybrid raymode representation is developed using the finite Poisson summation formula. The modal representation is modified in such a way that all the modes near resonance are retained while the truncated remainder of the mode series is expressed in terms of a weighted contribution of rays. For a large cavity, the contribution of rays from far away images becomes small, therefore the ray sum can be approximated by one or two dominant terms without a loss of numerical accuracy. To illustrate the accuracy and the computational simplification of this raymode representation, numerical examples are included with the conventional mode series (summed at the expense of long computation time) serving as a reference.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 September 1987
 Bibcode:
 1987STIN...8818763W
 Keywords:

 Cavities;
 Green'S Functions;
 Imaging Techniques;
 Mathematical Models;
 Scattering;
 Boundary Value Problems;
 Points (Mathematics);
 Poisson Equation;
 Transformations (Mathematics);
 Communications and Radar