Implementation of high order surface impedance boundary conditions using vector approximating functions

In this paper a technique to couple high order surface impedance boundary conditions (SIBC´s) with the vector boundary and finite element formulations is proposed for both low- and high-frequency problems. The use of high order SIBC´s enables to improve the accuracy of the computations and take into account the effects related to the curvature of the conductor surface. It is shown that the implementation of the Mitzner SIBC does not lead to new numerical difficulties compared to classical Leontovich SIBC´s. A numerical example is included to illustrate the theory