Microwave measurement of complex permittivity by placing a microstripline resonator on the material under test

The relative dielectric constant, epsivr, is calculated by quasi-static and frequency-dependent hybrid-mode analysis of three dielectric layers after measuring the rate of change of the resonating frequency by placing a microstripline resonator on the material under test. This method corrects the fringing effect of the resonator by using two resonators that have slightly different resonating frequencies. In the present study, tandelta is calculated by balancing the conductor loss and radiation loss using the rate of change of the Q factor. Using this method, the epsivr and tandelta values of materials having a low dielectric constant (epsivr: 1.05), thick materials (1,000 mm), thin sheets (50 mum), soft sheets and printed circuit boards without metallic patterns can be measured. This new measurement method is useful for measurement in the range 0.5~14 GHz, and fully automatic calculation can be achieved by computer analysis through connection to a network analyzer. This is a non-destructive method of measuring epsivr and tandelta