Passive Sensing Through Near-Field Coupling Interaction of Loaded Transmission Line

In this paper, a method for the detection of foreign metallic object in an enclosed chamber where loaded transmission line is positioned in one of the enclosing plane, is presented. The sensing principle is based on observed changes in the reflection coefficient depending on the position and size of the foreign object. The enclosed chamber is filled with a material having certain dielectric properties mimicking those of edible liquid. The transmission line is coplanar waveguide (CPW) and the loading particles are split ring-resonators (SRRs) which are designed to work in the S-band microwave range. The simulation works showed that the proposed sensor has acceptably accurate results, in which foreign object with various size and position can be detected. The sensor prototype can be developed for many sensing scenario, including to detect foreign object in a food processing facility.