Analysis of Freshwater Curved and Flat Spiral Antennas

Recent research shows that freshwater mussels are very effective as biological sensors for measuring pollutant levels in rivers. Electronic assembly mounted on top of mussel shells, or backpacks, measures the periodic opening and closing of the valves that is directly related to the nitrogen content of the water. These sensors communicate with a surface station through a radio operating at 300 MHz. Mussel backpacks require light-weight, small, broadband antennas with high efficiency in freshwater environment. Conventional spiral antennas satisfy these requirements but are ill-fitted to the curved shell surface. In this work, we design low-cost curved spiral antennas for mussel backpacks. Our numerical experiments with FEKO indicate relatively constant reflection coefficient of curved spiral antenna in freshwater at 300 MHz with values comparable with the flat spiral geometry.