Measurement for Determination of Dielectric Material Permittivity Using Air-Host SIW Structure

This paper discusses the determination of dielectric material permittivity using an air-host substrate- integrated-waveguide (SIW) structure through measurement. The air-host SIW structure is made by a copper plate with the thickness of 0.45 mm for the SIW surface and the groundplane. It has the dimensions of 85 mm (length) x 38 mm (width) x 4.8 mm (height) with the cut-off frequency of 3.875 GHz for the fundamental TE<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</inf> resonance mode. The material under test (MUT) used in the determination includes Arlon AD250A and FR-4 Epoxy dielectric substrates which takes a cylindrical shape with the dimensions of 18 mm (diameter) by 4.8 mm (height). The mechanism of measurement using the proposed air-host SIW structure is conducted by placing the MUT between the SIW surface and the groundplane. Based on the results, the accuracy for determining the dielectric material permittivity reaches up to 97.87 %.