A Canadian Perspective on Arctic and Polar Over-the-Horizon Radar

Two classes of Canada-specific Over-the-Horizon Radar (OTHR) systems are defined. Arctic OTHR (A-OTHR) systems are situated outside the auroral oval but perform some of their azimuthal scan in the direction of the oval. Clutter from ionospheric irregularities associated with the aurora must be suppressed over a finite azimuth extent, which can be done with a planar receive array that is either regularly sparse or oversampled sparse. Polar OTHR (P-OTHR) systems are situated inside the polar cap, and must suppress clutter from all azimuth angles. Auroral clutter control in P-OTHR systems requires a planar array that is either oversampled sparse or fully sampled.