The manufacturers claim that RDI will detect 90% of 5m^2 fighter-sized targets out to 66nmi (122km) in clear air using a four-bar search pattern over 120 degrees in azimuth, and 60 nmi (111km) with a single-bar pattern over 30 degrees in azimuth, dropping to 50 nmi (93km) in pulse-Doppler look-down mode." Why would the detection range decrease using a smaller horizontal and vertical azimuth? Actually the manufacturer is not strictly saying the detection range is less, they mean the odds of you detecting the target is reduced (very fractionally). And yes I realise it comes down to a similar thing, its just the perspective put on it. In principle it should not, a 30deg single bar scan would pass over the target 16 times to the 4 bar scan once (assuming constant scan rate), so the odds would be much greater of breaking the target from noise floor. Especially if specifying a moving target and platform (ie reflection power varying). If target position is known then it will not matter which scan pattern you use provided a bar of the 4 bar scan sweeps out the same area of sky as a single bar scan sweeping over target, but this depends on how the manufacturer sets up the mechanics of the antenna scan. However, at extreme range, the target needs to be pretty well central in the 3dB beam width for max power to be reflected back to the receiver. As the target range increases so the adjacent scan pattern beams overlap. So your odds of detecting a target can be marginally increased. A target right on the extreme edge of the beam bandwidth may be seen 'better' by the adjacent scan. You are seeing an example of manufacturer specmanship. Often these values are quoted by systems engineers maths ( especially modern stuff), backed up by flying a target at a known height and path through a range, whilst you try to detect it. With a single bar at extreme range you have to be pointing antenna boresight right into it, a multi bar may see it less precisely aimed. Sorry if I aint described this very well, I am a very long in the tooth radar engineer.