Measurements of loss tangent and permittivity at 60 GHz using an open resonator

Abstract

A new 60 GHz open resonator system has been developed to measure the permittivity and loss tangent of low-loss microwave and millimeter wave hard substrate materials. The system uses a new measurement method namely the cavity-length variation technique to determine the position difference and the profile of the resonance peak with and without the specimen for the calculation of the permittivity and loss tangent. A 20-nanometer length resolution is reached for the variation of the cavity length. This new technique provides an interferogram containing a number of resonance peaks with and without the specimen each having a complete Gaussian or Lorentzian profile. The real part of the dielectric permittivity and loss tangent can now be determined accurately. It is no longer necessary to use a stable, wide- band and tunable frequency source. The accurate data for some hard substrate materials is obtained, excellent agreement is obtained between the new data and the data extrapolated from the Fourier Transform Spectroscopy technique measurements.