Development of RF system and Dual Feed Patch Array Antenna for Beam Steering and Polarization Control for Monitoring Bacterial Contamination in Waters

Bacterial contamination monitoring is challenging because it requires manual sampling of the water to accurately analyze the level of bacterial contamination at a certain point in time. However, algorithms exist that use water temperature, pH, turbidity, and dissolved oxygen information, instead of manual sampling, to ascertain the bacterial contamination level with high accuracy. Most water quality monitoring sites use the cellular network to wirelessly send water quality data to a central system. However, due to limitations of cellular coverage, not all bodies of water cannot be monitored. Cellular networks also require a SIM card and subscription, and the energy consumption is very high. We investigate an RF system and array antenna for LoRaWAN for energy efficiency and long-range data transmission in remote locations where there is limited cellular coverage as well as a low-energy, low-cost alternative to cellular networks. In this work, we developed an RF system and patch array antenna for the gateway antenna that can steer the beam to the target water quality monitoring sites to improve the signal-to-noise ratio and received signal strength intensity to minimize packet drops and ensure data transmission. A 1x2 dual feed patch array antenna is designed at 2.4 GHz in CST software, board layout completed in KiCAD, fabricated, then tested in our Starlab antenna measurement chamber. The RF attenuator, RF power splitters, and phase shifters are measured and characterized using vector network analyzers (VNA) for the beam steering and polarization control. This modular system can be scaled to larger arrays with higher gain and narrower beamwidth for increased range of coverage and resolution to monitor many monitoring sites at low cost and high energy efficiency. Ultimately, the aim is to provide real-time bacterial contamination data to the public efficiently and effectively, to provide equitable water quality information to all local communities.