Title:  A Loss Tangent Measurement Surface for Free Space Focused Beam Characterization of Low-Low Dielectrics

Committee: 

Dr. Hunt, Advisor

Dr. Allen, Co-Advisor 

Dr. Durgin, Chair

Dr. Mazumdar

Abstract: The objective of the proposed research is to design and develop a physics-based technique for measuring dielectric loss from planar samples in a free space, microwave focused beam system, to design and provide a framework for a frequency-selective surface (FSS) that alters the scattering parameters of the sample to im- prove measurement sensitivity, and to evaluate the sources of measurement error in both the measurement system and this loss tangent measurement surface (LTMS) that challenge the success of the technique. A general framework for the design of the LTMS based on frequency of interest, necessary loss tan- gent sensitivity, and sample thickness will be developed. Sensitivity analysis, computational modeling, and measurements of the focused beam system will elucidate characteristics of the system that influence the de- sign of the FSS. For example, the error model of the focused beam system will inform whether a reflection- or transmission-based FSS will yield more accurate complex permittivity results. One or more surfaces will be designed and constructed to evaluate the performance of the measurement technique. The error model developed to influence design of the LTMS will be applied to the measurement of various known dielectric samples in the focused beam system, and accuracy of the LTMS technique will be assessed in the context of existing measurement techniques.