Comparative study of textile material characterization techniques for wearable antennas

Abstract

A comparative study of Quarter-wavelength λ4 stub and ring resonator techniques for the characterization of four (4) different textile materials (Kente-Oke (M1), Sanya (M2), Alaari (M3) and Etu (M4)) are presented in this work for the first time. The materials characterized in this work are locally made handwoven textile called “Aso-Oke” in South-west, Nigeria. The simulation and measurement results are presented. The dielectric parameters of materials were found to be 1.68, 1.46, 1.32, 1.51 for M1, M2, M3, and M4 respectively, and corresponding loss tangent of 0.049, 0.061, 0.019, 0.059 using Ring resonator. In the same light, the permittivity of the material M1, M2, M3, and M4 are found to be 1.75, 1.75, 1.5, 1.5 respectively, and corresponding loss tangent of 0.5, 0.6, 0.2, 0.6 using Quarter-wavelength open end Stub resonator. Using the parameters extracted from characterization, the materials are used as the substrate for wearable antenna to validate the measured dielectric properties of the material under test (MUTs). The results of this work show that, stub technique is more accurate than the ring resonator techniques. This is because of the complexity of ring resonator technique which makes it prone to fabrication error compared to the simplicity of the stub resonator technique. However, stub resonator technique can be time consuming due to the manual adjustment of the relative permittivity of the material during simulation. It is observed from the results of this research that, the stub resonator results are comparable to the Ring resonatorbased results. Hence, combining the two techniques by using the ring resonator to predict the region of the relative permittivity and then using the stub resonator technique to optimize the accuracy by varying the permittivity around the predicted region provided by ring resonator technique shall reduce the time consumed by Stub-resonator and increases the accuracy of the measurement.