Reference-invariant permittivity and thickness measurement of lossy liquid materials

A microwave method has been proposed to retrieve the complex permittivity and thickness of lossy dielectric liquids, which result in at least 10 dB attenuation, using reference-plane-invariant reflection scattering (S-) parameters. The CST Microwave Studio simulation program was first used to validate the method. Then, the permittivity and thickness of lossy distilled water sample poured over a polyethylene sample holder were measured from reference-invariant reflection-only S-parameter measurements at the X-band. The method was compared with other methods in the literature to analyse its accuracy.