An X-band microwave bridge for the measurement of complex permittivity

The author describes a versatile frequency-stabilized X-band microwave bridge which uses the cavity perturbation method to measure the temperature dependence of the complex dielectric permittivity of small samples (volume of the order of 1 mm³). Low temperature as well as high temperature experiments can easily be carried out using the same set-up. First results of the temperature-dependent permittivity of PVDP (polyvinylidenefluoride) thin foils are presented.