Improving measurements of granular and liquid materials permittivities in the microwave range

This paper describes a technique to improve the accuracy in measurements of dielectric constants of liquids and granular materials. Two pieces of low loss dielectric material (plugs) are placed inside a waveguide to house the sample under measurement. The expression for the S/sub 21/ transmission parameter is derived here to take into account the multiple reflections within the plugs. The S-parameter method is employed in combination with Newton´s complex iterative method to solve a nonlinear system of equations. Comparative numerical results are produced.