The HF Radar (High Frequency) is a technology that allows obtaining marine surface current maps and wave measurements through stations located on land.
It is based on the emission of electromagnetic waves and the study of the echo after reflection by the sea surface. The velocity of the surface current can be derived from the change in frequency between the emitted and reflected signal. This is a result of the Doppler effect, which is the apparent change in frequency of a wave produced by the movement of the source with respect to the observer.
Measurements can have a range of two hundred kilometers, depending on the wavelength used. The obtained data is representative of a depth of about one meter.