Measurement of permitivity of biological tissues from 300 MHZ to 3 GHz using an open-ended coaxial line

A comparative numerical study of three probe types with the same radial dimensions, three probe models, and five reference materials is presented for six biological tissues: liver, muscle, kidney, heart, blood and fat. The Probe-Model-Reference (PMR) combinations that lead to the most accurate results of the permittivity at frequencies from 300 MHz to 3 GHz are investigated for a coaxial probe without flange, a coaxial probe with flange, and a coaxial probe open into a propagation circular wave guide. The probe models considered are capacitive model, antenna model, and virtual line model. The reference materials are distilled water, 0.02 M NaCl(aq) solution, ethanol, methanol and 0.5 M NaCl(aq) solution. The results corroborates that when measuring the RF permittivity of biological materials using an open-ended coaxial line the proper selection of the probe type, probe model and reference material is crucial if good accuracy of measurements is expected. The presented methodology could be useful not only for the design of experiments, but also for the development of improved coaxial probes