A regular two-dimensional over-sampled sparse receiving array for Over-The-Horizon Radar

This paper considers the problem of increasing the sensitivity of the receiving system in an Over-The-Horizon Radar. We are concerned with the problem of detecting small targets in noise during night-time operation when reduced ionospheric propagation support limits the radar operating frequency to the lower part of the HF band and the external noise environment is higher than during daytime. Our receiving array design uses both over-dense array element spacing and sparse element spacing in a two-dimensional regular element configuration. The physical layout is both practically realistic and robust to ionospheric decorrelation effects for receiving arrays with very large spatial extent. We show that this design achieves performance close to the existing one-dimensional designs, but, unlike the current receiving arrays, scales in performance to the sensitivity levels required in future OTHR systems.