Characterization of electromagnetic properties of textile materials for the use in wearable antennas

This paper proposes a dedicated characterization technique based on textile microstrip line measurements for determining the textile substrate´s permittivity and loss tangent. The two-line method was applied to different textile transmission line configurations for calculating the effective permittivity and attenuation. Large deviations on the permittivity as a function of frequency were found due to geometrical inaccuracies of the transmission line structures, non-identical coax-CPW transitions and parasitic mode excitation. Here we apply the two-line method [4] in combination with the matrix-pencil method as an averaging technique to minimize the errors in the extracted material properties. Results of three different textile substrates constructed from the same base material are presented in the range from lGHz-lOGHz. In addition, planar antenna design was performed to validate the results of the proposed method.