Radiation and scattering of electromagnetic waves at the surfaces of composite materials: Surface immittance characterization via field compensation theorem

This research addresses a specific class of electromagnetic problems concerning the radiation and scattering of high frequency electromagnetic waves at the surfaces of composite materials. With the advent of need-based developments in electromagnetic material technology, a research niche has stemmed to analyze the interaction of electromagnetic energy with different versions of composite materials used mostly as surface materials such as in radar-stealth applications. Mixture-dielectrics, mixture magnetic materials, textured electromagnetic composites with matrix layers of lossy dielectric/magnetic materials, chiralic media, active surface materials etc. are a few emerging candidates of viable composites being considered in the state-of-the-art engineering electromagnetics. Specific to these materials, the analyses pertaining to electromagnetic radiation and scattering problems require a unique, approach vis-a-vis the heterogeneous properties of the composite material surfaces involved. Presently, the proximity of such surfaces is characterized and duly accounted for, by a mutual immittance formulation based on the Monteath's field compensation theorem. Using the relevant theoretical considerations, electromagnetic plane wave and/or focused beam radiation due to an aperture, conducting patch on flat and curved surfaces and scattering by an object coated with a composite material are elucidated. Also, an experimental method of evaluating the surface immittance is indicated. Theoretical computations are validated by comparing the results with those obtained via other methods. Some experimental results are furnished in support of the theoretical approaches presented.