Differentialy excited coupled-line sensor for small dielectric samples detection

In this paper, a novel method for dielectric sample detection in a microwave frequency range has been presented. The proposed measurement setup composed of two identical baluns and a coupled-line section sensor covered by an unknown dielectric material has been analyzed and formulas allowing for calculation of effective permittivity have been derived. The method allows for detection of small dielectric samples having size comparable with separation between sensor's coupled strips and therefore is dedicated for detection of bacteria in e.g. water, food etc. The proposed system has been theoretically investigated and verified by EM calculations.