Electrodynamics of materials for dielectric measurement standardization

Dielectric reference materials are analyzed in light of the fundamental requirements of linearity, homogeneity, and isotropy. The author presents generalized frequency- and temperature-dependent dispersion relations which allow the prediction of broadband dielectric behavior from limited measurement data, determination of valid modal field structure in cavity or waveguide fixtures, and identification of discrepancies and errors in measurement data. An approach to examining the influence of deviations of sample homogeneity on a precisely specified electromagnetic field structure is outlined, and sufficient conditions for isotropic, uniaxial, or biaxial anisotropic dielectric behavior are examined in terms of a material's chemical lattice physics. These characteristics direct the choice of suitable reference materials useful in dielectric metrology. Advances at the National Institute of Standards and Technology in both transmission/reflection and cavity resonator measurements incorporating dielectric reference materials are noted.<>