Waves in Anisotropic and Birefringent Artificial Dielectrics
O'brien, James Michael
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https://hdl.handle.net/2142/66241
Description
Title
Waves in Anisotropic and Birefringent Artificial Dielectrics
Author(s)
O'brien, James Michael
Issue Date
1980
Department of Study
Electrical Engineering
Discipline
Electrical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Language
eng
Abstract
The recent need for light weight multiple beam communication satellite antenna systems has stimulated renewed interest in artificial dielectrics. The particular dielectric studied is comprised of periodically spaced square arrays of thin square metallic obstacles. The major objectives of this study are first, to determine why the lenses previously built with this material failed to perform properly, and second, to design a functional lens if possible. The wave propagation properties of this type of medium are found using a full wave analysis. An equivalent multiport network models the modal conversion at the obstacle plane. An eiganvalue problem is then formulated to determine an effective index of refraction and wave admittance for the periodic structure. These bulk properties are subsequently used to analyze the propagation of a microwave beam incident on a medium. The refraction of a beam through a simple dielectric slab is considered first because one can include the effects of both the multiple internal reflections and the susceptive discontinuities at the boundary surfaces. Then the more practical prism structure was considered, since the prism has two refracting surfaces like the lens. The theoretically predicted results are verified by experiments with good agreement. These preliminary results indicate the possibility of designing a microwave lens which satisfies Abbe's sine condition by taking into account the inherent deliterious properties of this material, namely anisotropy and birefringence.
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