Using Coaxial Probe for Broadband Microwave Characterization of Biological Tissues

A key advantage of using coaxial probe for microwave characterization of biological media is the non-invasive nature of the technique. It is being used extensively for the complex permittivity measurements of materials in the microwave region. Usually, coaxial probe measurements require electromagnetic full-wave analysis or a calibrated reflection coefficient, S₁₁, of the material under test. In this paper, we present a new coaxial probe technique for the microwave characterization of biological tissues based on the calibrated reflection coefficient S₁₁ of a know dielectric constant. This technique only needs the well known distilled water as a reference material for the broadband microwave characterization of biological tissues. The complex permittivities of normal tissues from animals and both normal and cancerous tissues from human bodies were measured over a broadband microwave region with this technique. The biological tissue measurements showed that the complex permittivities measured by this technique are in good agreement with other investigations. This is a cost effective, non invasive and easy to use technique which makes it very suitable for diagnostic and therapeutic applications of microwaves in biomedicine.