Scattering of a plane electromagnetic wave from a semicircular crack in a perfectly conducting ground plane
Abstract
The scattering of TM and TE plane electromagnetic waves from a semicylindrical crack in a perfectly conducting ground plane is determined using a dual series eigenfunction expansion technique. Orthogonality properties of the sinusoids are used to reduce the solution to the inversion of a truncated infinite matrix. When the radius of the crack is much smaller than the wavelength, small argument approximations for the spherical radial functions are employed to simplify the results and remove the kadependence from the necessary numerical matrix inversion. In this small crack limit, closed form results are developed for both polarizations, and for the TM polarization, results are found to be different by only a constant factor from those for TM scattering from a narrow slit in an infinitely thin conducting screen. TE scattering from a small crack is found to differ significantly from TE scattering from a narrow slit, which indicates that the slit approximation is not valid for real situations that more closely resemble physically an indentation, or crack.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 April 1989
 Bibcode:
 1989STIN...9022721H
 Keywords:

 Cracks;
 Electrical Resistivity;
 Electromagnetic Scattering;
 Plane Waves;
 Polarized Electromagnetic Radiation;
 Eigenvectors;
 Electromagnetic Pulses;
 Inversions;
 Orthogonality;
 Communications and Radar