Microwave measurement of complex permittivity of a sheet material under test sandwiched between sheet metal and a calibrated stripline resonator

The relative dielectric constant, epsiv_r is calculated by quasi-static and frequency-dependent hybrid-mode analysis of two layers of dielectric materials (a sample material and a resonator base material) after measuring the rate of change of the resonating frequency of a sheet material under test sandwiched between sheet metal and a calibrated stripline resonator. This method corrects the fringing effect of the resonator by using two resonators that have slightly different resonating frequencies. In the present study, tan delta is calculated by balancing the conductor loss. The features of this method are: 1) Measurement of epsiv_r and tan delta in the E-H field direction of the actual test material, e.g., a printed circuit board. 2) Requires no fabrication of the metal pattern on the sheet material under test. 3) Measurement that provide accurate data because of no radiation loss. This 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.