A Geometric Theory of Natural Oscillation Frequencies in Exterior Scattering Problems.
Abstract
The representation of the transient electromagnetic response of finite size, smooth, perfectly conducting objects in terms of a complex exponential series is the central ingredient of the singularity expansion method (SEM). The exponential terms correspond to the complex natural frequencies associated with the object geometry. That such a simple series can predict the force free response of complicated objects begs the question 'is there not a corresponding more direct method to compute the natural frequencies in exterior scattering problems.' To partially answer this question a geometric ray optics method, which because of its asymptotic nature is particulary suited to compute the higher order resonances, is described. The electrical path length depends upon the local principal radii of curvature of the surface. The primary result of this work is that a generalized WKB method can be employed to account for both the curvature and impedance boundary conditions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 30, 1979
- Accession Number
- ADA079304
Entities
People
- Allen Q. Howard Jr.
Organizations
- University of Arizona