The Waveguide Method and Free-Space Method for Measuring the Electromagnetic Parameters of Materials

Based on the principle of the transmission-reflection method, this paper derives the formulas for testing the electromagnetic parameters of materials using the free-space method and waveguide method. It explains the issues of thickness resonance and multi-valued problems in the transmissionreflection method and provides solutions. For polytetrafluoroethylene (PTFE) material, both the free-space method and the waveguide method are used for testing, and the results are compared. The results show that the waveguide method provides higher accuracy. Simulation software is used to simulate the waveguide method, and a good consistency is observed when compared with the experimental data.