Measurement of dielectrics at 100 GHz with an open resonator connected to a network analyzer

A high-Q hemispherical open resonator is connected to an automatic network analyzer to enable precise and fast determination of the permittivity and loss tangent of low-loss dielectric materials at 100 GHz. Both scalar theory and vector theory with a frequency variation method are used to determine the dielectric properties of low-loss materials which are used in quasioptical components, for example in fusion reactor windows and tenses for millimeter-wave receivers. The uncertainty of the measurement is 0.02% to 0.04% for /spl epsi//sub r/(/spl epsiv//sub r//spl ges/2) and 6-40/spl times/10/sup -6/ for tan /spl delta/(10/sup -4//spl les/tan /spl delta//spl les/10/sup -3/).