LP-WAN Nodes with Integrated Leaf Wetness Sensors

This paper introduces an innovative Low-Power Wide-Area Network (LP-WAN) node, which integrates in a unique board a leaf wetness sensor (LWS), a microcontroller, a LoRa radio and a Planar Inverted-F Antenna (PIFA). Unlike the majority of traditional setups, where the node is an entity independent from the sensing unit (or units), connected to the node by external cables, our solution is more compact and highly resistant to possible damages. Moreover, it redefines the concept of weather station by using solely a capacitive leaf wetness sensor, which allows the leaf wetness duration (LWD) computation, pivotal for predicting and preventing several diseases like powdery mildew and downy mildew. The whole board was optimized by means of CST Studio simulations, including antenna simulations. After board realization, tests were done in anechoic chamber to prove the RF performance. The node configuration allows deployments within the crops, in any operational conditions, enhancing its portability, reducing its footprint, and simplifying installation. Initial results demonstrate adequate radio-frequency performance, compared to nodes with external antennas. Future works will explore energy consumption patterns over time and validate long-term packaging durability.