Incremental diffraction coefficients for cylinders of arbitrary cross section: application to diffraction from ridges and channels in perfectly conducting surfaces

The direct substitution method of R.A. Shore and A.D. Yaghjian (see IEEE Trans. Antennas Propag. vol.36, no.1, p.50-4, 1988) is extended to perfectly conducting canonical scatterers (i.e., cylinders) of arbitrary cross section. This is done by first showing that the scattered fields outside the cylindrical radius rho =a, from a scatterer located within the radius rho =a, can be generated by electric and magnetic surface currents on a single planar strip inside the radius rho =a. The analysis and results of Shore and Yaghjian are then applied to these equivalent electric and magnetic currents to obtain general expressions for incremental diffraction coefficients of perfectly conducting cylinders of arbitrary cross section. These expressions are evaluated with far fields, for narrow cylinders, ridges (2-D bumps) on ground planes, and channels (2-D dents) in ground planes.<>