Theory of the Scattering of Electromagnetic Waves by Irregular Interfaces

Author: Mitzner, Kenneth Martin

Year: 1964

Degree: Dissertation (Ph.D.)

Advisor: Papas, Charles Herach

Committee Member: Unknown, Unknown

Option: Electrical Engineering

DOI: 10.7907/HBEY-GT07

Abstract

Two problems involving electromagnetic scattering from irregular interfaces are treated, both deterministic and statistical irregularities being considered.

First, reflection of a partially polarized plane wave from a plane interface with large irregularities is studied using geometrical optics. Matrix transformations relating incident and reflected waves are obtained for reflection from a single specular point and from an extended area containing many independent reflectors. The properties of a wave reflected from a diffusely illuminated rough interface are found, and these results are used to study reflection noise reduction when a polarization-sensitive detector viewing near the Brewster angle is used in infrared temperature measurements.

Second, the method of small perturbations is used to study scattering of an arbitrary completely polarized wave from an irregular interface of general underlying shape. The irregularities are replaced by equivalent surface currents and then the field in space is found using the dyadic Green's functions of the unperturbed problem. The results obtained are valid when the irregularity has small slope and amplitude small compared to the wavelength and local radii of curvature. To facilitate applications, the theory of dyadic Green's functions is developed, and the necessary functions are evaluated for simple geometries. As an example, the first perturbation is calculated for scattering from a perfectly conducting cylinder with sinusoidal irregularities.

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