A Permittivity-Sensitive Sensor with a Sensing Area based on a Resonator with Two Legs Stretched Inwards

In this work, an antenna-based sensor is proposed to monitor permittivity variation. On FR4 epoxy of 12x12x1.5 mm³, our structure was designed, and then validated on HFSS (High Frequency Structure Simulator) software and CST (Computer Simulation Technology). The feed line of antenna and the sensor detection zone were etched on the top and bottom of the substrate, respectively. To distribute the maximum E-field in the detection zone, a slot based on resonator with two legs stretched inwards (RTLSI) was introduced on the ground plane of our antenna. To test the sensor’s sensitivity, MUTS (Material Under Test) were putted alternatively on the RTLSI slot. The sensor’s sensitivity was estimated by a polynomial of third degree. This sensor is able to detect a relative permittivity variation with sensitivity equal to 1.2 to 6.3 times the sensitivity of sensors presented in previous works; in addition, the size of sensor was reduced.