For the first time, a 3less (batteryless, chipless, wireless) underground sensor system was developed for real time monitoring of variations in temperature, humidity, and hydrogen gas concentrations around underground utility burials. The completed sensor system consists of several magnetic core antennas, surface acoustic wave (SAW) sensors, and a measurement system. Each SAW sensor was activated by pure magnetic energy, and showed high sensor performances in sensitivity and linearity. A long readout distance was observed between the upper and underground antennas, and wireless magnetic communication was analyzed in terms of the interdistances, the angles between antennas, and the underground constituent mediums. A circulator was employed to discern magnetic signals emitting and receiving in between the upper and underground systems. A COMSOL simulation and coupling of mode (COM) modeling were also conducted to determine optimal design parameters for the sensor modules, and to predict the experimental results in advance.

中文翻译：

---

基于磁芯天线和多个声表面波传感器模块的地下无线传感器网络的部署

首次开发了 3less（无电池、无芯片、无线）地下传感器系统，用于实时监测地下公用设施墓葬周围温度、湿度和氢气浓度的变化。完整的传感器系统由多个磁芯天线、表面声波 (SAW) 传感器和测量系统组成。每个 SAW 传感器都由纯磁能激活，并在灵敏度和线性度方面表现出很高的传感器性能。观测到上部和地下天线之间较长的读出距离，并从间距、天线之间的角度和地下组成介质等方面分析了无线磁通信。一个循环器被用来辨别在上层和地下系统之间发射和接收的磁信号。