Whilst this may seem to be a disadvantage, the SAMPSON radar rotates at 30 revolutions per minute, with two back-to-back arrays, meaning no part of the sky lacks coverage for more than one half second on average - the precise time varies as the beams can also be swept back and forth electronically. In addition, the use of a smaller number of arrays allows the system to be much lighter, allowing placement of the arrays at the top of a prominent mast rather than on the side of the superstructure as in the Dutch or US ships. Placing any radar emitter at higher altitude extends the horizon distance, improving performance against low level or sea-skimming targets; SAMPSON is at approximately double the height above the waterline than the arrays of its Dutch or US equivalents. Although precise details of the SAMPSON's performance in this regard are unlikely to enter the public domain, such factors may mitigate the disadvantages of fewer arrays.