A High-Sensitive Cavity Sensor Antenna With Interference Suppression Ability Based on Spoof Localized Surface Plasmons

Matter detection based on strong microwave resonance has been widely studied. However, most of the currently available high-precision sensors are wired mode, making them difficult to enable no-contact detection. In this work, a high-sensitive cavity sensor antenna based on spoof localized surface plasmons (SLSPs) is proposed, which can be used for no-contact sensing monitoring (wireless mode). Since the frequency response of the sensor antenna is very sensitive to changes in the refractive index of environment, high-precision detection can be achieved and the data can be transmitted in real time back to a receiver placed in the no-contact area. The sensor is designed as an open antenna system that utilizes field enhancement of SLSPs to improve the cavity resonance, achieving measured high Q-factor of 135.6 and sensing figure of merit (FoM) of 37 RIU−1. In addition, the wireless mode brings the additional possible advantage of suppressing interference due to higher order resonances by designing the field distribution of antenna aperture to design radiation patterns. This allows the receiving antenna, which is directly in front of the sensor antenna, not to be subjected to multiple resonances interfering with each other as in the wired mode, and therefore greatly extends the sensing range of the dielectric constants from 1 to 1.1 in the wired mode to at least 1–2.3.