Title

Electromagnetic scattering from chiral cylinders of arbitrary cross section

Date of Award

1994

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical Engineering and Computer Science

Advisor(s)

Ercument Arvas

Keywords

Electromagnetic scattering, chiral cylinders

Subject Categories

Electrical and Computer Engineering | Electromagnetics and photonics

Abstract

In this dissertation, the problem of electromagnetic scattering from a chiral cylinder of arbitrary cross section has been formulated using the surface equivalence principle and then solved numerically using the method of moments. The Green's dyads for chiral media are used to develop explicit expressions for the coupled copolarized and crosspolarized electric fields produced by two-dimensional electric and magnetic current distributions in an unbounded chiral medium. The surface equivalence principle is used to replace the chiral cylinder by equivalent electric and magnetic surface currents radiating in unbounded media. A set of coupled integral equations is obtained by enforcing the boundary conditions on the tangential components of the total electric field. The resulting surface E-field integral equations are solved by the method of moments with point matching and pulses as expansion functions. The problems which are considered in this research include both TM$\sb{\rm z}$ and/or TE$\sb{\rm z}$ plane wave incidence.

Numerical results, including echo widths and internal fields for several chiral cylinders of different parameters are found and reported in this dissertation. The numerically obtained data are in excellent agreement with the exact data found by the eigenfunction solution for the circular chiral cylinder. The effect of adding chirality to the scatterers is investigated throughout the numerical results of several chiral cylinders of different shapes and material parameters. The results demonstrate the feasibility of the employment of chirality in applications such as to control the radar cross section (RCS) of scatterers and in the synthesis of anti-reflection composite materials. It is also observed that although the effect of chirality on RCS is noticeable, it is not predictable by a simple theory. The method developed in this dissertation to treat scattering from chiral cylinders of arbitrary cross section can be easily extended to address problems of scattering by two-dimensional chiral radomes and by chiral-covered conducting cylinders. The method can, also, be extended to three-dimensional chiral objects of arbitrary shape. The advantages and limitations of the method are briefly discussed.

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