Investigations on the three theoretical models of permittivity measurement for biological tissues

Comparative studies of three theoretical models relating the coaxial line end reflection to the permittivity of sample under test (SUT) are presented, including capacitance model, virtual line model and impedance model. The basic principles of these three models are introduced briefly at first; then their accuracies in measuring lossy biological materials are then tested. In our work, the porcine liver is used as a sample of biological tissue with relatively high permittivity, while porcine fat representing the biological tissue with low permittivity. The permittivity for the two biological tissues is extracted respectively using the three models and compared with known reference data. The validity of the three models in different frequencies and permittivity range are discussed.