A Novel Transmission Line Phase Technique for Complex Permittivity Measurement

A novel transmission line phase measurement method is proposed to facilitate the measurement of complex permittivity of the material under test (MUT). The overall process is noninvasive and nondestructive, which uses the measured S-parameter phase of the MUT putting on a microstrip resonant ring. The four phases of the S-parameter corresponding to the resonant frequency are extracted when the MUT is placed on the resonant ring. And the characteristic phase with the four phases can be calculated. Then the relative dielectric constant εr and the loss tangent tan δ of the MUT can be extracted the phase of S
₂₁
and characteristic phase, respectively. The measurement results show that the proposed method has the advantages of efficiency and convenience.