Studies in Diffraction.
Final rept. 1 Jan 72-31 Dec 76,
MICHIGAN UNIV ANN ARBOR RADIATION LAB
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Focuses were on techniques for high frequency scattering determination with particular emphasis on edged bodies. The two main methods are the geometrical theory of diffraction GTD and the physical or fringe wave theory PTD. The former is an extension of geometrical optics through the inclusion of diffracted rays. It requires a knowledge of the diffraction coefficient associated with each local source of diffraction, but is a physically-based theory in which the various parts are actually observable. It is in principle capable of predicting second and higher order contributions to the scattering, but in common with all ray techniques it requires the incorporation of matching functions to ensure finite estimates of the fields at caustics where an infinity or rays come together. The second major area was a consideration of material effects in scattering with particular reference to the use of the impedance boundary condition and resistive and conductive sheets in simulating the behavior of absorbers.
- Radiofrequency Wave Propagation