A NEW MODEL FOR MICROWAVE CHARACTERIZATION OF COMPOSITE-MATERIALS IN GUIDED-WAVE MEDIUM

A method of determining the permittivity and the permeability of heter ogeneous materials from microwave measurements in a coaxial line or in a rectangular waveguide is presented, Fluctuations are observed in th e curves of the transmission and reflection coefficients measured in a guided space cell which are caused by the propagation of modes higher than lowest order. The measuring cell containing the sample is repres ented by an unperturbed line in series with resonators which model the coupling between the sample and the measurement cell for each higher mode resonating inside the sample. Finally, the intrinsic characterist ics of the material are computed from the data for the unperturbed lin e. Results for several composite materials and measurement cells are p resented to demonstrate the capabilities of this model.