Measurement of dielectric permittivity and loss tangent for bulk foam samples with suspended ring resonator method

The present study discusses a new microstrip-based resonant device that is specifically intended for foam measurements at frequencies 1-10 GHz. It is based on a microstrip ring resonator. However, the ring and the feed network are physically located in separate planes, thus enabling the placement of an arbitrary sample of material to be measured in the substrate of the ring resonator. A transmission line method (TLM) is used to predict the frequency response. Preliminary experimental data in L- and S-bands are presented and compared with theory estimates for the foams