Date of Award

6-2012

Degree Type

Dissertation

Embargo Date

8-17-2012

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical Engineering and Computer Science

Advisor(s)

Ercument Arvas

Second Advisor

Joseph R. Mautz

Subject Categories

Engineering

Abstract

A chiral body of revolution (BOR) which is partially covered by a thin conducting shield is analyzed using the method of moments (MOM). The axisymmetric system is excited by a plane wave. The total internal fields and the far scattered fields are computed. The problem is solved using the surface equivalence principle. The scattered fields outside the structure are assumed to be produced by an equivalent magnetic surface current that exists on the unshielded part of the BOR surface and an external equivalent electric surface current that exists over all of the BOR surface . These two currents are assumed to radiate in the unbounded external medium. Similarly, the total internal fields are assumed to be produced by the negative of the above magnetic current and an internal equivalent electric surface current that exists over all of the BOR surface, but is the negative of an independent unknown only on the shielded part of . These two currents radiate in the unbounded internal medium. Enforcing continuity of the tangential components of total electric field (E) and total magnetic field (H) on S gives a two coupled integral equations for the two unknown surface currents. The two unknown surface currents are the external equivalent electric surface current and the union of magnetic current ( ) on the unshielded part of and the negative of the internal equivalent electric surface current on the shielded part of . The method of moments as applied to bodies of revolution is used to solve these integral equations numerically. Piecewise linear variation of the currents is assumed along the generating curve of the BOR. The variation of the currents along the circumferential direction is represented by Fourier series. An approximate Galerkin's method is used for testing. Conical and spherical BORs are studied. Computed results for the partially shielded spherical chiral body are in excellent agreement with other data.

Theoretical framework developed in chapters two through six factually validated the underlying firm foundation of mathematical physics and sound computational electromagnetic methods of our theory by producing correct scattered fields and radar cross sections of the chiral and perfectly conducting sphere, chiral and perfectly conducting cylinder, chiral and perfectly conducting cone. Chapter seven demonstrates the soundness of the theoretical foundation of this thesis by producing computed results and graphs of not only the case of a perfectly conducting sphere, cylinder and cone but those of the chiral sphere, chiral cylinder, and chiral cone and those of the chiral sphere, chiral cylinder and chiral cone partially covered by rotationally symmetric perfectly conducting surface. The computed results and graphs obtained in chapter seven by the application of our theoretical framework were almost one hundred percent accurate with respect to the conformability of our graph mappings, form of our graphs and accuracy of our graph readings with respect to analytically calculated results and graphs. Our computed results and graphs with respect to the computed results and graphs of early research works that used numerical approach distinctly different than ours were in good agreement.

Access

Open Access

Included in

Engineering Commons

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