Nondestructive permittivity measurement of substrates

The complex permittivity, κ'[1-j(tan δ)], of a thin, flat dielectric is calculated from the characteristics of the H₀₁₁ 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