The scope of impedance boundary conditions in radio propagation

The surface impedance boundary condition is a useful concept when dealing with the analysis of radio wave transmission over inhomogeneous surfaces. The justification for the method is not rigorous but confidence is gained by examining a number of canonical problems where exact solutions are obtainable. The scope of the surface impedance postulate is reviewed, and its relevance in radiowave propagation and related applications, such as magnetotelluric probing of the subsurface, is indicated.