Broadband Quasi-Optical Dielectric Spectroscopy for Solid and Liquid Samples

Dielectric materials play a supporting role for electronic circuits. With the development of 5G millimeter wave communication, precision measurement of dielectric property becomes increasingly important. This paper introduces a free-space quasi-optical spectroscopy for complex dielectric property measurement. This spectroscopy can work in both transmission and reflection modes to accommodate both low-loss and high-loss materials. By applying the transfer matrix theory, both solid and liquid samples can be characterized using this system. In addition, the system employs a Gaussian telescope design, giving a possibility of broadband operation. Furthermore, this system is much simpler in calibration compared to other systems. A detailed description of the quasi-optical system is presented. Four materials are measured in the E-band (60–90 GHz). De-ionized water is also measured to represent liquid substrates in electronic circuits. The measurement is in good agreement with published data within a discrepancy of 5%.