A Numerical Study of Influence of a Matching Medium on Transmission Coefficients Between Antennas Used in Microwave Imaging System

Abstract

New perspective methods for medical imaging are constantly developing and improving in present time. One of these methods is so-called Microwave Imaging (MWI), which uses non-harmful and non-ionizing microwave radiation and its research is focused mainly on two areas, breast cancer detection and brain stroke classification. At ELEDIA@CTU research centre was developed the prototype of MWI system for brain stroke detection and classification. For testing of the prototype, realistic phantoms of a human head are fabricating. To provide ideal contact between antennas used in MWI system and phantom matching mediums are using. The contribution presents some numerical results of the influence of three different matching mediums to transmission coefficients ( $S$ parameters) measured by MWI system in the environment of numerical simulator COMSOL Multiphysics. Numerical simulations showed that for distilled water used as matching medium the highest values of transmission coefficients (−50 dB) are gained but these values are distorted by low conductivity of distilled water which caused propagation of EM wave through matching medium and not through phantom of human head. On the contrary more realistic results but lower values of transmission coefficients (−70 dB) are gained with mineral/salt water or ethanol used as matching medium. Results will help in near future to improve experiments with MWI system and heterogeneous layered realistic phantom where matching medium needs to be filled between antennas and phantom of human head.