Experimental trials on ionospheric clutter suppression for high-frequency surface wave radar

The unwanted radar echoes from the ionosphere are collectively called ionospheric clutter. This has proved to be the greatest impediment to achieving consistently good performance in long-range sea state monitoring for high-frequency surface wave radar (HFSWR). Ionospheric clutter can mask sea echoes having similar Doppler shifts. The potential for exploiting some fundamental characteristics of ionospheric clutter in directivity and frequency to suppress it is assessed. A post-Doppler spatial adaptive processing algorithm (PD-SAP) and the dual-frequency operation mode are introduced to suppress directional and non-directional ionospheric clutter, respectively. Experimental results confirm that both of these techniques can achieve effective ionospheric clutter suppression using the field experimental data recorded by the HFSWR OSMAR2003 (Ocean State Monitor and Analysis Radar, manufactured in 2003), located near Zhoushan in Zhejiang, China.