Planar Microwave Sensors Based on Coupled Ring Resonators and Applications

The potential of planar microwave resonators for sensing applications has been signified, when a single resonant structure is exposed to dielectric properties-variant environments. However, enhancing sensing parameters such as sensitivity, selectivity and dynamic range remains a continuing challenge. To address these challenges, coupled microwave resonant structures have been introduced in various microwave sensing applications. It is demonstrated that the quality factor of a coupled resonator system can be improved, and the dynamic range of sensing can be extended before the sensitivity saturation range is reached. In this chapter, the electromagnetic coupling between planar split ring resonators will be discussed. Their performances will be presented in simulation, mathematical analysis and experimental forms, and their outstanding performance in the introduced unique applications will be studied in wired and wireless readout methods. Moreover, it will be shown that not only the electromagnetic coupling of split ring resonators in wired systems enhances the dynamic range of the sensors, but also, in wireless readout systems, it increases the communication distance between an array of coupled passive split ring resonators and an interrogator antenna.