Signal structure of the over-the-horizon sea surface radar

Obtaining information about the state of the sea surface using HF radars has been the subject of intense investigations during the past several decades. Most theoretical investigations made to date have adopted, as the incident wave, a plane wave with a certain wave vector. In real conditions, however, with the finite beam width, the ionosphere-reflected beam of waves of a finite width is usually incident on the scattering sea surface, which must be taken into account when investigating the form of the spectrum and processing it by extracting information about the sea surface. This paper investigates the scattering of fluctuating ionospheric radio waves from the sea surface within limits of the geometrical optics by taking into consideration the finiteness of the beam of the receive and transmit antennas. A numerical simulation is used to investigate the influence of the finiteness of the beam width, the time of coherent integration, and ionospheric irregularities on the structure of the spectrum of the received signal of the overt-the-horizon sea surface radar.