High-frequency impedance of a practical metal surface and the effect of a thin coating of dielectric over it

It has always been assumed that the surface of metals used in h.f. cables and waveguides is sufficiently uniform to present an impedance, which is jointly resistive and inductive. The evidence of computations made here and of recent experimental observations incidates that many such surfaces may well be capacitive and that, in these circumstances, a thin dielectric coating can reduce the resistive component of the impedance.