Document Type


Date of Award


Degree Name

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


Electrical and Computer Engineering

First Advisor

Edip Niver

Second Advisor

Gerald Martin Whitman

Third Advisor

Gregory A. Kriegsmann


The radiation problem of the cylindrical dielectric taper, excited by the HE11 dominant mode, is studied. A theoretical model and a numerical investigation into the radiation characteristics of such a tapered structure are presented. The model is based upon the combination of the exact modal field solutions for a step profile cylindrical dielectric waveguide, Local Mode Theory, and the Equivalence Principle for the determination of equivalent current densities.

The far-zone radiation field is considered to be the summation of the fields produced by two radiative components in the dielectric rod/conical 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 volume polarization current density induced in the conical structure.

The resulting integral expressions for the far field are evaluated numerically by means of a computer program developed in FORTRAN 77. Numerical results are obtained for a number of different input data sets, where the parameters, such as, the free-space wavelength A, the dielectric core radius a, the refractive index of the core ni, the length of the taper, etc., are varied. Some of the results are compared with available experimental data; the agreement is found to be satisfactory.



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