Non-destructive characterization of dielectric materials by microwave spectroscopy in LS band

The paper describes the characterization of dielectric materials, by using a resonance based ring-resonator method. A microstrip ring resonator (MRR) method is presented to measure effective dielectric constant (ϵreff) of composite laminate materials. Multilayer structure of MRR is designed and simulated using Ansoft's High Frequency Structure Simulation. Comparative study of polytetrafluoroethylene (PTFE), ceramic and ceramic-PTFE composites have been carried out to analyze the åreff along with its dependence on sheet thickness. From results, it is clearly observed that as the thickness of overlay is increased there is significant change in effective permittivity, which is more noticeable for high-permittivity ceramic material than low-permittivity PTFE material. Measured data is found in good agreement with the reported data.