Document Type
Thesis
Date of Award
5-31-1986
Degree Name
Master of Science in Electrical Engineering - (M.S.)
Department
Electrical Engineering
First Advisor
Edip Niver
Second Advisor
Gerald Martin Whitman
Third Advisor
Peter Engler
Abstract
Conventional approach to a solution of a wave propagation problem in an inhomogeneous medium is to utilize either rays or modes to represent the wave field. Asymptotic ray theory (ART) starts to fail in the vicinity of caustics due to rays experiencing many reflections. Even uniform representations do not properly correct this deficiency of rays when caustics start to pile up in the far range. One possible alternative is to replace these rays with modal bundles and remainders [1]. A promising technique using Gaussian Beams has been used to represent the total field due to a point or a line source in an inhomogeneous medium [2]. The advantages of this method is that no search mechanisms are involved and beams poses uniform behavior around caustics. Results have been reported for an isolated caustic. The computer program SEIS.83 had been developed by Psencik and Cerveny to track rays in a numerically specified medium. This program is modified to implement the Gaussian Beam Method (GBM) during the course of this study. The assesment of this modification has been tested on various profiles (homogeneous and inhomogeneous). Then caustic forming rays with many surface reflections are replaced with Gaussian beams. Equivalence between these transitional rays and a bundle of Gaussian beams has been established. The critical parameters in a such equivalence are the width of the beam bundle 9 number of beams and beam width of an Individual beam. The reference solution for such transitional rays is the numerically evaluated ray integral or its equivalent in terms of modes and remainders [1]. Results have shown that the beam bundle and ray equivalence becomes less accurate as the number of surface reflections increases.
Recommended Citation
Ruiz, Carlos Javier, "Replacement of surface ducted rays near caustics with guassian beams" (1986). Theses. 3374.
https://digitalcommons.njit.edu/theses/3374
