Investigation of Systematic Errors of an Indirect Resonant Planar Material Characterization Method

Indirect measurement principles have always been presented as a solution to save simulation and modeling efforts for complex permittivity extraction methods. However, detailed investigations on remaining systematic errors as well as recommendation guidelines for reference material selection are missing in the literature. In this article, typical systematic error sources of a planar coplanar waveguide over ground material sensor are investigated. An indirect error compensation algorithm is presented, and its ability to compensate the main error sources is simulatively analyzed. A measurement setup is created by considering the specified requirements. The measurement principle is validated by measuring three different plastics. Overall, the results are plausible and have uncertainties of the same or lower order of magnitude compared with the state of the art. However, the findings show that indirect planar methods suffer from fundamental problems, which limit the achievable measurement uncertainty. The findings of this work can be used as a basis for decision-making when considering an indirect planar measurement principle.