Enhancement of sensitivity of microwave planar sensors with EBG structures

A strategy to improve microstrip sensor performance for monitoring dielectric properties of materials is proposed. The method relies on the reduction of the wave group velocity to induce higher interaction between the sensor and the material. This is achieved by the design of periodic patterns in the sensor ground plane, which exhibit electromagnetic band gap (EBG) effects. The presence of these EBG structures turns out to be highly effective, inducing a noticeable decrease of the wave velocity. The sensitivity is defined and measured for different sensor configurations in order to quantify the improvements obtained. It is observed that, with the EBG structures, the residence time of the wave in the material under test is longer, and a substantial increase of the sensor sensitivity is obtained.