Expanding the coverage of HF radar through the use of wave powered buoys

There are approximately 120 High Frequency (HF) radars deployed throughout the United States that are contributing to the Integrated Ocean Observing System (IOOS) National High Frequency Radar Network. The network is operational with the United States Coast Guard for search and rescue. These systems also posses a dual use capability for environmental monitoring with simultaneous detection of vessels at sea. These systems have ranges between 30 and 180 km offshore depending on the chosen frequency. These systems ability to measure the alongshore current is hampered by the geometry of the deployment locations. At the farthest ranges the radar can measure the cross-shore currents well while the alongshore current requires a scattering angle that is difficult to achieve with stations on land. We undertook a study to increase the coverage of HF radars through the use of an offshore transmitter. This bistatic signal increased the coverage of the HF radar network and also increased the number of look angles for current measurements. The signal was also used to extend the vessel detection capability of one of the radars. The placement of an offshore bistatic transmitter at key locations around the country can increase the accuracy and range of the National High Frequency radar network. The efficacy of the network's use in search and rescue, hazardous material spill response and homeland security can be increased through the use of offshore transmitters.