Millimeter-Wave Characterization of Dielectric Materials Using Calibrated FMCW Transceivers

This paper presents a measurement setup, an extraction algorithm, and the results from material characterization measurements in the millimeter-wave (mm-wave) regime using ultrawideband frequency-modulated continuous-wave (FMCW) radar transceivers. The complex permittivity of dielectric and nonmagnetic materials is derived from radar echoes using a high-gain dielectric lens antenna setup and a measurement setup comprising elliptic mirrors. The radar transceivers perform fast and accurate measurements from 200 to 250 GHz within milliseconds. The FMCW transceivers are calibrated using a frequency-domain model that describes the systematic errors in the measurement setup. The characterization is done by a holistic model-based approach. Several well-known dielectric materials, such as polytetrafluorethylene, polyvinylchloride (PVC), or acrylic glass, are characterized among others to validate the setup's accuracy. The characterization is also done for different samples of polylactide, which is commonly used in additive manufacturing processes and 3-D printing, making it of high interest for the construction of mm-wave components.