An investigation of impropriety and noncircularity in high frequency radar data

Discarding the phase content of signals from single-channel high-frequency (HF) radar is commonplace among practitioners in the field. From the perspective of complex-valued statistics, this practice implicitly implies that the complex-valued HF data is second-order proper or circular. This paper presents a preliminary investigation into the validity of this assumption using HF surface wave radar (HF-SWR) field data. It is found that the HF-SWR data is indeed second-order improper or noncircular. This negates the common belief regarding the non-informativness of the phase, and it warrants more in-depth analysis into characterizing impropriety/noncircularity for relevant HF radar applications.