Receiver design for HF ground-wave radar

Ground-wave radars, operating in the HF band, are becoming increasingly popular for both the remote sensing of the sea surface and for the detection of ship targets well beyond the normal radar horizon. This paper details the requirements of the radar receiver and describes the gating system and the advantages of using digital signal processing techniques for the narrowband receiver functions. A coastal based pulse Doppler radar system as shown is considered. An omnidirectional antenna is used, on transmission, to ´floodlight´ the sea surface. Directional information of the reflected target signal is then obtained using a wide aperture phased array antenna on reception. Effective target detection in the presence of sea clutter returns involves coherent integration of the echo, from a target, over a period of time which is in the order of 100´s of seconds. A single narrow beam scanned in azimuth, as in microwave radars, would result in the introduction of an unacceptable time delay before returning to a given bearing. Thus the radar must use multiple beam synthesis from the phased array for target tracking and acquisition.<>