Presentation Information
[C-2C-01]Underwater Salinity Estimation Using Sea-Surface Measurements with Dipole Antennas
◎Kotaro Mitsuyasu1, Toshiyuki Tanaka1, Koya Okubo1 (1. Nagasaki Univ.)
Keywords:
Seawater,Salinity,nanoVNA,Dipole antenna
The importance of underwater environmental monitoring has increased with the expansion of marine utilization, such as aquaculture and marine energy development. This study proposes an underwater salinity estimation method based on electromagnetic wave propagation characteristics using dipole antennas.
In the proposed method, the S21 frequency response between two dipole antennas is measured using a nanoVNA. A salinity estimation equation was derived from measurements of saltwater solutions with salinity concentrations ranging from 3% to 5% in the frequency range of 0.1–0.3 GHz. Laboratory experiments confirmed that the salinity of collected seawater could be estimated with an error of 0.09%.
For sea-surface measurements, an antenna cover and floating structure were fabricated to protect the antennas from waves and marine organisms. Measurements were conducted in the coastal area of Nagasaki City, Japan, with an antenna spacing of 5 cm. The salinity at the measurement site was 3.6% as measured by a digital salinity meter.
The estimated salinity averaged 3.754%, resulting in an average error of 0.154%. Although the target error of less than 0.1% was not achieved, the results demonstrate the feasibility of salinity estimation under actual marine conditions. Future work will focus on optimizing the antenna structure, antenna spacing, and antenna cover to improve estimation accuracy.
In the proposed method, the S21 frequency response between two dipole antennas is measured using a nanoVNA. A salinity estimation equation was derived from measurements of saltwater solutions with salinity concentrations ranging from 3% to 5% in the frequency range of 0.1–0.3 GHz. Laboratory experiments confirmed that the salinity of collected seawater could be estimated with an error of 0.09%.
For sea-surface measurements, an antenna cover and floating structure were fabricated to protect the antennas from waves and marine organisms. Measurements were conducted in the coastal area of Nagasaki City, Japan, with an antenna spacing of 5 cm. The salinity at the measurement site was 3.6% as measured by a digital salinity meter.
The estimated salinity averaged 3.754%, resulting in an average error of 0.154%. Although the target error of less than 0.1% was not achieved, the results demonstrate the feasibility of salinity estimation under actual marine conditions. Future work will focus on optimizing the antenna structure, antenna spacing, and antenna cover to improve estimation accuracy.