A Noniterative and Efficient Technique to Extract Complex Permittivity of Low-Loss Dielectric Materials at Terahertz Frequencies

In this letter, a noniterative technique is proposed to efficiently extract complex permittivity (ε) of low-loss dielectric materials at terahertz frequencies while mitigating the effects at Fabry-Perot frequencies. For this goal, the formula of ε with little resonance is first derived by applying boundary conditions for the transmission-reflection-based free-space method. In order to demonstrate the advantages of the proposed technique, we compared the proposed technique with the classical Nicolson-Ross- Weir method and the Newton-Raphson method. The proposed noniterative technique is verified by experiments and simulation at 220-325 GHz.