Efficient computation of surface fields excited on an electrically large circular cylinder with an impedance boundary condition

Abstract

An efficient computation technique is developed for the surface fields excited on an electrically large circular cylinder with an impedance boundary condition (IBC). The study of these surface fields is of practical interest due to its applications in the design and analysis of conformal antennas. Furthermore, it acts as a canonical problem useful toward the development of asymptotic solutions valid for arbitrary smooth convex thin material coated/partially material coated surfaces. In this thesis, an alternative numerical approach is presented for the evaluation of the Fock type integrals which exist in the Uniform Geometrical Theory of Diffraction (UTD) based asymptotic solution for the non-paraxial surface fields excited by a magnetic or an electric source located on the surface of an electrically large circular cylinder with an IBC. This alternative approach is based on performing a numerical integration of the Fock type integrals on a deformed path on which the integrands are non-oscillatory and rapidly decaying. Comparison of this approach with the previously developed study presented by Tokg¨oz (PhD thesis, 2002), which is based on invoking the Cauchy’s residue theorem by finding the pole singularities numerically, reveals that the alternative approach is considerably more efficient. Since paraxial solution is a closed-form solution and very efficient in terms of computational time, there is no need for an alternative approach for the evaluation of the paraxial surface fields.