engleski

EFFICIENT ANALYSIS OF CURVED AND PERIODIC ELECTROMAGNETIC STRUCTURES USING ASYMPTOTIC FORMS OF GREEN'S FUNCTIONS

This dissertation discusses the analysis of multilayered dielectric and periodic electromagnetic structures using different asymptotic approaches in order to simplify the derivation of the appropriate Green’s functions or to accelerate their evaluation and application. The acceleration method was developed for the analysis of curved multilayered waveguide arrays and frequency selective surfaces, where the principle of asymptotic extraction was applied in spectral domain analysis in order to reduce its numerical complexity. This was achieved by extracting the simplified “asymptotic problem” which was then solved using much more efficient methods. Since the “asymptotic problems” are not limited only to canonical shapes, an extension of the spectral domain approach to arbitrary curved multilayered structures was developed. Both, the acceleration approach and the extension for arbitrary curved problems, showed very good accuracy in comparison with the results of the existing solutions and measurements. Asymptotic approach was also applied in the analysis of novel gap-waveguide transmission line structures based on different periodic surfaces. In this case homogenized ideal or asymptotic boundary conditions for periodic structures were applied in order to derive Green’s functions for these novel structures. The obtained Green’s functions demonstrate not only that full analysis is possible, showing very good agreement with the already published results and measurements, but also provide a clear physical insight into the propagation mechanisms of these structures. Also, in order to further simplify the analysis of so-called electromagnetic bandgap structures, canonical boundary conditions that take into account the specific behavior of these surfaces were developed.

conformal antennas; multilayered dielectric structures; periodic structures; Green’s functions; spectral domain method; asymptotic boundary conditions

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