Plane-wave reflection properties of two artificially hard surfaces

The concepts of artificially hard and soft surfaces are interpreted in terms of the plane-wave reflection properties of the surfaces, in particular the reflection phase angles for two orthogonal polarizations. Numerical results are presented for two types of nearly hard surfaces. The first is a surface with longitudinally oriented and dielectrically filled corrugations. The second is a surface with longitudinally oriented strips on a grounded dielectric substrate. Neither of the two realizations is ideally hard in the strictest sense of the concept, but a good approximation can be achieved over a limited bandwidth. The numerical results demonstrate how various geometrical parameters affect the behavior of the surfaces. One important result is that the strip-loaded surface is the most favorable with respect to bandwidth. Another is that the strip-loaded surface can be made arbitrarily thin, though at the expense of bandwidth.>