Aperture Fields in an Anisotropic Medium

An integral equation for the tangential electric field excited in a slit by an H‐polarized plane wave in a gyrotropic medium, such as a magnetized plasma, is solved for a wide slit by a modification of the Wiener‐Hopf technique. The slit edges are parallel to the gyrotropic axis and normal to the otherwise arbitrary direction of incidence. Calculations for normal incidence on a slit with ka = 4 and 8, where k is the propagation constant in the medium and 2a is the slit width, show that the field becomes less uniform in both amplitude and phase with increasing anisotropy, demonstrating that the uniform field assumption used by some workers is invalid with appreciable anisotropy. The asymptotic form of this solution agrees with that obtained by geometrical diffraction theory, verifying earlier work based on this approach and providing a simple expression for the aperture field in slits of more than about two wavelengths in the medium.