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Nearly 30% of oil drilled globally is done offshore. Oil spillage offshore has far-reaching consequences on the environment, aquatic lives, and livelihoods as it was evident in the Deepwater Horizon and Bonga oil spills. A novel microwave in situ oil spill sensor was developed in this work. The device is comprised of two polydimethylsiloxane (PDMS)-encapsulated ultra-wideband underwater microwave trefoil antennas enclosed in a Faraday cage with one serving as the receiving antenna and the other as the transmitting antenna. Heavy aromatic-naphthenic Azeri crude oil was used as an inclusion in the seawater host medium. Substantial changes in the measured reflection (S11) and transmission (S21) coefficients were observed as the medium was adulterated with crude oil starting from 200 MHz to around 2500 MHz. The changes in the dielectric properties of the media resulted in changes in both the S11 and S21 signifying and detecting an occurrence of the oil spillage. Thus, by employing radio frequencies, oil spillage was detected using the in situ monitoring device in seawater.

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.