Selection of the surface impedance boundary conditions for a given problem

It is well-known that the surface impedance boundary conditions (SIBCs) are classified by their order of approximation. In the present paper universal relationships between characteristic values of the problem are proposed co nsidering the order of approximation so that the SIBCs, best suited to a gi ven problem, can be easily selected. The methodology is applicable to the t ime-frequency-domain linear and non-linear SIBCs. Numerical examples are in cluded to illustrate the methodology.