Accession Number : AD0275334

Title :   DIFFRACTION BY A CIRCULAR APERTURE IN A UNIDIRECTIONALLY CONDUCTING SCREEN

Corporate Author : HARVARD UNIV CAMBRIDGE MASS CRUFT LAB

Personal Author(s) : SESHADRI,S.R. ; WU,TAI TSUN

Report Date : 10 APR 1962

Pagination or Media Count : 1

Abstract : The diffraction of a normally incident plane electromagnetic wave with wave number k by a circular aperture of rdius a in a unidirectionally conducting plane screen of zero thickness and infinite extent is considered. In the limit of large ka, the ratio of the transmission cross section to the geometrical optics value pi a squared, is found up to the order (ka) to the -3/2 power. A new feature of this problem is that a set of rays in the sense of Keler's geometrical theory of diffraction emanates from the regions of the aperture rim to which the current on the screen is nearly tangential and proceed in all directions. However, for the case of normal incidence, these rays do not contribute to the transmission cross section up to the order (ka) to the -3/2 power. (Author)

Descriptors :   *ELECTROMAGNETIC RADIATION, *OPTICS, DIFFRACTION, LENSES

Distribution Statement : APPROVED FOR PUBLIC RELEASE