On higher-order diffraction concepts applied to a conducting strip

The derivation emphasizing cylindrical-wave diffraction is given for a high-frequency approximation to the diffraction of a plane wave by a conducting strip. The resulting formulation is basically the same as the formulations of Karp and Russek. The range of usefulness of this formulation has apparently been unrecognized. The validity of the approximation presented here is checked by comparison with the exact solution for strip diffraction; the backscattered field for normal incidence is in good agreement for strip widths larger than0.55\lambdaand in fair agreement for widths as narrow as0.125\lambda. This approximation and Keller's geometrical theory of diffraction, which uses plane-wave diffraction coefficients, are compared with measurements made by Ross. Diffraction patterns and echo widths for various incidence angles are calculated for various strip widths.