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Review and Modification of Permittivity Measurement on Open Resonator for Transparent Material Measurements at Terahertz

In this article, permittivity measurement based on open resonator technology is reviewed, and then, the hemispherical open resonator with an enlarged aperture on the curved mirror is proposed for high-frequency applications. A numerical compensate method based on frequency deviation is first proposed in detail for permittivity correction. To verify our idea, an open resonator is designed and fabricated over the frequency from 26 to 40 GHz, and some materials with known characteristics are measured based on proposed technology. The complex permittivity measurement of two transparent materials, polydimethylsiloxane (PDMS) and cyclic olefin copolymer (COC), are studied at 260 GHz. Measured results are compared with previous ones, and the discussion is provided, which shows that the proposed method probably is an efficient way for complex permittivity measurement at high frequency up to terahertz.