G4NSJ – notes on HF radar ocean surface waves codar


CODAR stands for  Coastal Ocean Dynamics Applications Radar. Its a type of HF radar system that’s used for remote sensing of ocean surface currents and waves. These systems are used in coastal areas and measure the direction and speed of ocean surface currents up to a range of 200 km from the shore.

The CODAR system uses the Doppler effect to measure the velocity of ocean surface currents. The system uses multiple antennas that are arranged in a linear or circular array along the coast. Each antenna radiates a continuous signal at a specific frequency. All the signals from the antennas are combined to create a beam that is directed out to sea. When this beam hits the ocean surface, it is scattered by waves and currents, and the scattered signal is received by the antennas. By analyzing the changes in the frequency of the scattered signal, the CODAR system determines the velocity of the surface currents.

CODAR systems are used in a variety of applications, including oceanographic research, search and rescue operations, and maritime navigation. They can provide valuable information about ocean currents and waves, which can help to improve ocean modeling and forecasting, as well as inform decision-making in a variety of marine industries.

I believe the frequencies used are between 4.6 and 50MHz. I’ll add further info as and when I get it.