Sporadic-E ionospheric clutter suppression in HF surface-wave radar

The unwanted radar echoes from the ionosphere are collectively called ionospheric clutter. It has proved to be the greatest impediment to achieving consistently good performance in long-range detection of surface vessels and sea state monitoring for HF surface wave radar (HFSWR). Ionospheric clutter can mask target/sea echoes having similar Doppler shifts. Main characteristics of sporadic-E ionospheric clutter (Es-layer clutter) are described. A new time domain coherent side-lobe cancellation (CSLC) algorithm based on subarrays is proposed to suppress this type of ionospheric clutter. Experimental results confirm that the general algorithm can achieve effective ionospheric clutter suppression while not decreasing the strength of the first-order sea echo using the data recorded by the OSMAR2003 (ocean state monitor and analysis radar, manufactured in 2003), located near Zhoushan in Zhejiang China.