Accession Number : AD0830042

Title :   COMPATIBILITY STUDIES. VOLUME V. APPENDIX 4. DIFFRACTION OF A PARABOLIC CAUSTIC BY AN IMPEDANCE PLANE.

Descriptive Note : Final rept. Apr 64-Oct 67,

Corporate Author : MOORE SCHOOL OF ELECTRICAL ENGINEERING PHILADELPHIA PA

Personal Author(s) : Houng, Shun-Jen

Report Date : FEB 1968

Pagination or Media Count : 92

Abstract : In many of the propagation problems the incident field into the terrain is of a more complex type than a plane wave. One such complex field is a caustic. A caustic arises when part of the space is illuminated and the remaining part is in a shadow. Specifically it is the locus of the points which mark the illuminated to shadow region boundary. This type of situation occurs in high gain antennas in propagation behind obstacles, etc. The scattering of a caustic by an impedance plane has been examined in this paper. The impedance plane here is an idealized approximation of a slightly conducting plane earth. The scattering integrals of this type of surface have been evaluated and the physical mechanism involved in the launching of surface waves was examined. A new result of this work was the proof, that for certain angles of incidence one obtains maximum launching efficiency of a surface wave. This may have interesting practical implications in certain geometries where caustics, generated behind obstacles, are capable of launching surface waves which may completely change the nature of the propagation mechanism. (Author)

Descriptors :   (*ELECTROMAGNETIC RADIATION, DIFFRACTION), PROPAGATION, BOUNDARY VALUE PROBLEMS, CURVED PROFILES, SCATTERING, ELECTRICAL IMPEDANCE, PARABOLIC BODIES, INTEGRALS, LOCUS, COMPLEX VARIABLES, ELECTROMAGNETIC COMPATIBILITY.

Subject Categories : Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE