Efficient Moment Method and Hybrid Moment Method Solutions for the EM Scattering by a Dielectric Loaded Rectangular Cavity in a Ground Plane.

摘要

Two efficient moment method (MM) solutions are developed for the electromagnetic scattering by a two-dimensional rectangular cavity recessed in a perfectly conducting ground plane and loaded with a homogeneous lossy or lossless dielectric. The unknown to be found in this MM solution is only the aperture electric field because of the use of special Green's functions for a conducting half-space and a fully closed conducting rectangular cavity. Both the TE and TM polarizations are treated. One MM solution employs a waveguide modal basis or expansion functions to represent the unknown aperture electric field and yields a solution which is efficient for narrow to moderately wide (<25 wavelengths) cavities of arbitrary depth. The use of an alternative form of the cavity Green's function further adds to the efficiency. The second MM solution uses a hybrid set of basis functions dictated by the physics of the problem; this hybrid solution is very efficient for treating wide and shallow cavities. Furthermore, the number of hybrid basis functions remain nearly a constant (about 10 or less) no matter how wide the cavity gets. Numerical results are shown to establish confidence in both approaches by comparing them with each other and with a conventional MM solution using pulse basis.