Multiterm Debye Dispersion Relations for Permittivity of Muscle

摘要

Permittivity is an essential variable in any scattering or absorption derivation using Maxwell's equations. Therefore, the patterns of absorbed radio frequency radiation (RFR) in tissues are determined, in part, by the electrical properties of the tissues. The common practice seems to be to interpolate tabulated data for dielectric permittivity and conductivity rather than consider the inherent dependence of the two terms of the complex permittivity on each other. Presented here are expressions which fit the relative permittivity data of muscle from 10 Hz to 100 GHz. A computer program was developed to fit multiple-term Debye-type expressions to published data of permittivity for muscle. The number of terms in this expression was varied and tested for significance. Based on these results, closed form expressions for dielectric permittivity and conductivity are suggested for use as estimators over the 10 Hz to 100 GHz range.