Microwave reflection intensity measurement for dielectric material using a single probe

Microwave reflection intensity for microwave absorber, Cu-plate and Al2O3 (1 0 0 0) single crystal substrate was measured from 8 to 11 GHz as a function of distance between single probe and sample at room temperature. The minimum reflection intensity was observed in the distance of 0.2 mm between single probe and sample at 9.4 GHz, although the reflection intensity was decreased with increasing distance in other measurement frequencies. The electromagnetic field analysis was hence carried out for simulation model that is defined with coaxial cable, probe and sample using finite differential time domain method. The reflection coefficient and impedance for simulation model were calculated, and compared to the experimental data. The results of electromagnetic analysis shows that the minimum point of reflection intensity was caused from an impedance matching.