Fast, Nondestructive, and Broadband Dielectric Characterization for Polymer Sheets

We propose a compact nearfield scheme for fast and broadband dielectric characterization in the microwave region. An open-type circular probe operated in the high-purity TE₀₁ mode was developed, showing a strongly confined fringing field at the open end. This fringing field directly probed the freestanding sheet sample, and the overall reflection was measured. Without sample-loading processes, both of the system assembling time and the risk of sample damage can be significantly reduced. In addition, the nearfield measurement substantially simplifies the calibration and the retrieval theory, facilitating the development of easy-to-integrate and easy-to-calibrate dielectric characterization technique. The dielectric properties of more than ten polymers were characterized from 30 GHz to 40 GHz. We believe that this work fulfills the requirement of the fast diagnostic in the industrial manufactures and also provides valuable high-frequency dielectric information for the designs of 5G devices.