Measuring the permittivity of thin samples in the X band: a thickness-independent technique

A new method is proposed for determining the permittivity of thin materials in the X band and estimating their thickness. The procedure consists of measuring two reflection coefficient values at the input of a waveguide modified to accommodate the material under measurement and then computing the unknown parameters by means of a numerical procedure employing a genetic algorithm. The method has been tested on certified dielectric materials and it can be successfully applied to materials whose thickness is not constant (i.e. leaves). Results concerning paper and thin cardboard are presented.