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IEEE Transactions on Antennas and Propagation
Volume 46 Number 7, July 1998

A Uniform GTD Treatment of Surface Diffraction by Impedance and Coated Cylinders

Page 998.

Abstract:

In the context of the uniform geometrical theory of diffraction (UTD), computation of the scattered fields near the shadow boundary of a smooth convex surface requires values for the Pekeris-integral function p^*(\xi, q). While in a small number of cases such as the case of perfect conductivity (q = 0 and q arrow \infty), tabulated values of the function are available; in the general case, these values must be obtained by some numerical method. Here, a procedure for approximating p^*(\xi, q) by residue-series means will be introduced. In contrast with traditional residue-series representations, the new procedure requires only a limited knowledge of pole locations even in the shadow boundary transition region and thereby extends the regime of practical applicability of residue-series methods beyond the deep shadow. It will be demonstrated that the new procedure can be combined with an earlier residue-series representation derived by this author and R. Albus (and with geometrical optics) to provide a computationally efficient procedure for computing fields scattered by an impedance or coated cylinder.

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