The Measurement of Permittivity Using TE01 Mode in a Cylindrical Waveguide Beyond 300GHz Frquency Band

Abstract

As the use of Terahertz (THz) frequency band in various research area such as natural science, material science, and communications system increases, the material permittivity which is one of important properties of material in high-frequency region becomes essential. However, accurate complex permittivity measurement in the frequency band beyond 100GHz is very difficult, therefore, references of permittivity data of materials are still lacking.1 One of the measurement methods in low-frequency uses a fundamental TE10 mode in the rectangular waveguide. However, it cannot be used in high frequency region because the dimension of experimental setup becomes diminishing, therefore, the air gap effect which causes disruption of resonance peaks grows bigger. In comparison to the TE10 mode, the TE01 mode has proven to provide very accurate measurement due to its low fields at surface of waveguide.2 Furthermore, the measurement using the TE01. mode is also easier from sample size limitation. In this paper, we present the extended research on the permittivity measurement by using the TE01 mode in the frequency beyond 300GHz from our previous work in W-band. Detail study will be performed with various samples for demonstrating the reliability of the TE01. mode measurement in THz frequency region.