Measurement of complex dielectric permittivity of medium and low loss materials at 36.624 GHz and 52.263 GHz using a single iris rectangular cavity resonator

A novel technique based on cavity perturbation for the characterization of dielectric properties of medium and low loss homogeneous cylindrically shaped materials using a single iris coupled rectangular resonator in Ka and millimeter-wave band frequencies is presented in this paper. The relative permittivity and the dielectric loss have been calculated using the conventional perturbation method. Simultaneously, simulation measurements are also done for unperturbed and loaded cavity resonator. Simulated results demonstrate the degradation in accuracy of the derived relative dielectric constant with increasing sample radius. Hence, a first-order correction factor has been added with conventional expression of dielectric permittivity proposed in cavity perturbation method to stabilize the value of dielectric permittivity at higher sample radius. This proposed method eliminates any cavity perturbation, originating from the variations in sample size. The dielectric samples are tested at Ka-band frequency of 36.624 GHz and also at mm-wave band having frequency of 52.263 GHz.