Determination of Complex Permittivity of Analytes Using Terahertz Metamaterials

ABSTRACT

We present a comprehensive simulation study demonstrating a novel method to determine the complex permittivity of analytes using the resonant behavior of metamaterials operating in the 0.2–1.5 Terahertz (THz) frequency range. Full‐wave electromagnetic simulations were performed by overlaying analyte layers with ranging from 1 to 12 and from 0 to 0.5 onto the THz metamaterial surface. The results show that the resonant frequency shift gradually saturates at an analyte thickness of approximately 10 µm due to the strongly confined near‐field distribution around the metamaterial gap region. In contrast, the transmission variation remains sensitive to additional analyte thickness beyond 10 µm because of continued propagation‐related absorption within the bulk analyte region. Our analysis reveals that the resonant frequency shift () is predominantly governed by the real part of the permittivity, whereas the transmission variation () is influenced by both the real and imaginary parts of permittivity. Based on these relationships, a two‐dimensional contour map was established to enable the direct and simultaneous extraction of from the obtained resonance responses. This approach provides a simplified and computationally efficient route for quantitative THz characterization of lossy liquid analytes.