The Effect of Rough Seas on Phase-only Direction Finding with Circular Arrays in the HF Band

High frequency (HF) surveillance requires robust direction-finding solutions regardless of the varying sea conditions. Circular arrays are a reasonable candidate for this and similar needs, as the phase mode theory can be applied to locate the direction-of-arrival of a received signal. However, the presence of a rough sea surface causes electromagnetic wave interactions that may distort radiation patterns and thus the detected complex voltage values. These distortions affect the direction-finding in unwanted ways. The impact of Beaufort sea states ranging from 0 to 5 on the accuracy of the phase-only direction finding is theoretically explored in this work. Computational experiments are carefully executed to determine this effect at HF band.