Comparisons of Complex Permittivity Measurements Using Free-Space and Waveguide Fabry-Perot Resonators at E/W-band Frequencies

Dielectric materials with the real relative permittivity ranging from 5 to 16 are studied thoroughly at 60-110 GHz using the free-space quasi-optical and waveguide Fabry-Perot interferometer measurement techniques. The optical n and k constants can be obtained accurately even though the undesired standing waves resulting from the imperfection interfaces in the measurement system cause strong spikes in the measured Fabry-Perot interference fringe pattern.