Comparison of reflection-transmission method and metal-backed method for textile composites using free-space microwave techniques

For measurements of dielectric materials, a free-space measurement system was developed in the frequency range of 8 - 12.5GHz. The key components of the measurements system are a pair of spot-focusing horn lens antennas, the network analyzer and the coaxial cables. In this project the objective is to analyze, measure the reflection and transmission coefficients S₁₁ and S₂₁ of the dielectric materials for textile composites using reflection-transmission and metal-backed methods at microwave frequencies and compare the results for getting the better method in measurement. Complex electric permittivity (Ɛ*) is calculated from the measured values S₁₁ and S₂₁ by using computer program Fortran 77 for metal-backed method and C++ programming for reflection-transmission method.