Integrated Micro & Nano Systems, University of Edinburgh, Edinburgh EH8 9AB, UK.
Sensors (Basel). 2021 Feb 13;21(4):1337. doi: 10.3390/s21041337.
There is an increasing interest in water bodies, which make up more that seventy percent of our planet. It is thus imperative that the water environment should be remotely monitored. Radio frequency (RF) signals have higher bandwidth and lower latency compared to acoustic signals. However, water has high permittivity and conductivity which presents a challenge for the implementation of RF technology. In this work, we undertook a novel design, fabrication, measurement and implementation of an antenna for a sensor node with dual ability of underwater and water surface long range (LoRa) communication at 868 MHz. It was observed that the antenna's performance deteriorated underwater without -10 dB effective bandwidth between 668 MHz and 1068 MHz. The introduction of an oil-impregnated paper buffer around the antenna resulted in an effective 400 MHz bandwidth within the same frequency span. The sensor node with the buffered antenna was able to achieve a distance of 6 m underwater and 160 m over water surface communication to a data gateway node. The sensor node without the buffered antenna was only able to achieve 80 m over water surface communication. These experimental results show the feasibility of using the LoRa 868 MHz frequency in underwater and water surface communication.
人们对水体重的兴趣日益浓厚，而这些水体占据了我们星球的百分之七十以上。因此，必须对水环境进行远程监测。与声信号相比，射频 (RF) 信号具有更高的带宽和更低的延迟。然而，水的介电常数和电导率较高，这给射频技术的实现带来了挑战。在这项工作中，我们进行了一项新颖的设计、制造、测量和实施工作，设计了一个工作在 868MHz 的具有水下和水面远距离（LoRa）通信双重能力的传感器节点天线。观察到天线在水下时性能下降，在 668MHz 至 1068MHz 之间没有 -10dB 的有效带宽。在天线周围引入油浸纸缓冲器后，在相同的频率范围内实现了 400MHz 的有效带宽。带有缓冲天线的传感器节点能够在水下实现 6m 的通信距离和在水面上实现 160m 的通信距离到数据网关节点。没有缓冲天线的传感器节点只能在水面上实现 80m 的通信距离。这些实验结果表明，在水下和水面通信中使用 LoRa 868MHz 频率是可行的。
