Document Type

Thesis

Date of Award

10-31-1993

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical Engineering

First Advisor

Edip Niver

Second Advisor

Gerald Martin Whitman

Third Advisor

Gary Wu

Abstract

The radiation fields from a cylindrical dielectric taper is studied. The numerical results of a theoretical model for a taper excited by the dominant HEn mode is compared with experimental measurements. A theoretical mode] for the next propa¬gating mode in the structure. the TE01 mode. is investigated and numerical results based on this proposed model are generated. The theoretical models are based upon the combination of the exact modal field solutions for a step profile cylindrical dielectric rod waveguide. local mode Hum-T. and the equivalence principle for the determination of equivalent current densities.

The far-zone radiation field is considered to be the summation of the two radiative components in the dielectric rod/cone structure. The -aperture- of the uniform dielectric rod at the transition plane (rod/cone interface) and the dielectric taper itself. In the former case. the field is obtained from the equivalent surface current densities on the aperture surface. whereas in the latter case. the field is obtained from the equivalent volume polarization current density induced in the conical structure.

Numerical results are obtained using a number of different input data sets. where the parameters such as the free-space wavelength A, the refractive index of the dielectric nl and the length of the taper are varied. These are then compared against the experimental observations and a. satisfactory agreement. between the two sets of data is achieved.

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