Time-Domain Free-Field Measurements of the Relative Permittivity of Building Materials

Time-domain free-field measurements comprised the dielectric properties of several common building materials using dual-ridged guide antennas and 1 mtimes1 m samples placed on an optical table covered with an absorber. The samples are polycarbonate, gypsum, plywood, a brick wall, and a concrete wall. Time gating and deconvolution are used to isolate a sample´s front and back surfaces to obtain the measured reflection coefficients (RCs) and transmission coefficients. Theoretical reflection and transmission equations were generated from a plane-wave model. Relative permittivity is obtained by varying the parameters in the Kirkwood-Fuoss equation until a best fit between the theoretical and measured reflection and transmission coefficients is obtained.