PROCEDURE FOR ACCURATE AND STABLE CONSTITUTIVE PARAMETERS EXTRACTION OF MATERIALS AT MICROWAVE FREQUENCIES

A non-resonant microwave method has been proposed for accurate and stable constitutive parameter measurement of low-loss dispersive and non-dispersive isotropic materials. The method uses transmission-only measurements of two configurations: a) the sample inside a sample holder and b) the sample backed by a reference sample inside the same holder. It is not prone to undesired ripples in the extracted constitutive parameters arising from measured similar reflection properties. In addition, its accuracy is higher since it is not much affected by surface roughness and/or unevenness of the sample or the reference sample. It is based on frequency-by-frequency extraction and thus suitable for dispersive materials. However, it requires the selection of an appropriate reference sample. The method has been validated by measurements at Xband (8.2--12.4 GHz) of a low-loss sample located into a waveguide sample holder.