Arctic Over-the-Horizon Radar Receive Array Design Considerations

An Arctic over-the-horizon radar system should be located so that the boundary of the aurora borealis lies at one-half its maximum range. At this location, the ionosphere reflection point is generally outside the aurora and auroral backscatter clutter arrives from close to the horizon. The optimal depth of an AOTHR two-dimensional receive array for clutter mitigation is given by the spread of the clutter spatial autocorrelation. Endfire element spacing is limited by the appearance of grating lobes at the horizon.