Nondestructive permittivity measurement of substrates

The complex permittivity, kappa[1 - j(tan delta)], of a thin, flat dielectric is calculated from the characteristics of the Hell resonance in a cylindrical cavity with the specimen inserted on the central transverse plane, Dielectric constants from 1 to 300 have been measured with errors less than 1%, The resolution of the loss tangent measurement is approximately 10 ppm at 12 GHz, No irreversible specimen preparation is required, and its shape and size, if larger than the cavity diameter, are arbitrary, Analysis and verification are presented in this and a companion paper [1].