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Electrical Characterization of Novel Materials

Understanding material properties (dielectric constant and loss tangent) are crucial in designing next-generation antennas and RF components at millimeter wave (30-300 GHz) and terahertz (>300 GHz) bands.

In our group, we have developed a free space measurement technique using terahertz time domain spectroscopy (TDS). Using the THz TDS, phase and amplitude of the transmitted wave is measured in the frequency range of 200 GHz –1.2 THz. Using the transmission data and an analytical propagation model, complex permittivity and a thickness of the sample are calculated. We use the Debye relaxation to model the complex permittivity of the material and extrapolate the results for lower frequencies.

Figure 1: (a) Amplitude and (b) phase of the transmittance for 0.78 mm-thick sample. Measured data are compared with the analytical and simulation model. Figure 2: Propagation model for transmission measurement

We have measured the complex permittivity of the paraffin using this method. Paraffin is a low-loss phase change material that is used in the design of millimeter wave reconfigurable structures.

Figure 3: Real part of relative permittivity for various sample thickness. Figure 4: (a) Extrapolated and (b) extracted values of loss tangent. Error bars represent one standard deviation.

© Prof. Nima Ghalichechian's Group

Related Papers

B. Ghassemiparvin and N. Ghalichechian, “Broadband Complex Permittivity Measurement of Pariffin Flims at 26GHz-1 THz Using Time Domain Spectroscopy," IEEE International Symposium on Antennas and Propogation (APSURSI), San Diego, CA, 9-14 Jul, 2017. DOI: (Download PDF).

B. Ghassemiparvin and N. Ghalichechian, “Permittivity and Dielectric Loss Characterization of Paraffin Films for mmW and THz Applications,” IEEE International Workshop on Antenna Technology (iWAT), Cocoa Beach, FL, 29 Feb-2 Mar, 2016. DOI: (Download PDF).