A Wireless Non-Metallic Pipeline Liquid Level Sensor Based on Spoof Surface Plasmon Polaritons

This paper presents a wireless sensor based on spoof surface plasmon polaritons (SSPPs), which can be used to measure liquid level in non-metallic pipe in real time. This sensor is flexible and can be bent and wound around the pipe at will. A pair of ultra-wideband flexible antennas with orthogonal polarization directions were provided at both ends of the sensor to receive excitation signals and transmit signals. A pair of horn antennas connected to two ports of VNA were used to stimulate and receive signals of the whole system. When the liquid level of the pipeline changes, the S ₂₁ amplitude and asymptotic frequency of the system will change. Taking a Teflon pipe with a thickness of 2-3 mm and a radius of 55 mm as an example, it can be proved experimentally that the sensor can detect the liquid level with a resolution of 1 mm. Compared with the traditional liquid level detection sensor, this sensor can penetrate the container for measurement, and has the advantages of simple structure, high precision, lower cost and smaller volume.