Measurement of complex permittivity of microwave dielectric materials using TM0mn modes

A novel method for measuring the complex permittivity of dielectric plates is proposed by using TM0mn modes in a closed cylindrical resonant cavity. The analysis based on the Ritz-Galerkin method, mode matching technique and transmission-mode quality factor measurement method is performed, and the formulas for calculating the complex permittivity are developed. Finally, a sweep-frequency measurement of the complex permittivity is conducted on high molecular weight polyethylene(HMWPE) using an Angilent vector network analyzer. Within the frequency range of 3~6 GHz, the relative permittivity and loss tangent of HMWPE turn out to be 2.30±0.05 and (1.8~2.0)×10-4, respectively.