Background loss of amorphous dielectrics in the high frequency and microwave region

Abstract

Dielectric background loss follows a power temperature law over a wide range of frequencies, temperatures and materials : tan δ=ATⁿ. Data on polyvinylchloride and polymethylmethacrylate are used to separate conductivity, relaxation, and background loss employing this temperature law.

An interpretation of the background loss as due to the anharmonic coupling of the electric field to acoustic modes is discussed. The power temperature law is explained by the change in population numbers of the phonon states involved, and changes in the slope of the loss factor against temperature curves are interpreted by a change in the coupling parameters.