Measurement of dielectric permittivity based on a microstrip line: comparison of two implementation methods

Abstract: In this paper, an analysis of two following ways to implement the measurement of permittivity based on a microstrip line was carried out: 1) when the dielectric is located above the signal conductor (open microstrip line); 2) when the dielectric is located between the non-metallized base (substrate) and the grounded metallized surface (suspended microstrip line). Based on the modeling and the experimental research carried out, a comparison of both methods was performed with an assessment of their applicability for materials of different thicknesses and a range of dielectric permeabilities. For the considered range of materials with low losses and dielectric constant from 2 to 100, it was determined that the open microstrip line is applicable for measuring the dielectric constant of materials with a thickness of more than 5 mm, while the suspended microstrip line, due to geometric features, is more suitable for materials with a thickness of 1 mm or less.

Keywords: vector network analyzer, differential phase method, microstrip transmission line, effective dielectric constant