Architecture and signal processing of sky wave over-the-horizon radar

The sky wave over-the-horizon radar (OTHR) is unique in the radar family that employs the ionosphere to reflect the radar high frequency signal to illuminate the target from the top down, thus significantly extending the detection range and permitting wide-area surveillance. Besides, the OTHR also shows its special advantages on low-flying target detection, stealth target detection, and sea-state remote sensing. This paper presents an overall review on the development and architecture of the sky wave OTHR as well as the signal processing schemes. In particular, the techniques on interference suppression, correction of ionospheric contamination, and target detection are analyzed in detail.