The Surface Movement Radar at Luton has been there for a long time, pre all the development that has taken place over the last 10 years or more. The location of any single source surface radar tends to be a bit of a compromise given all the buildings on an airport, and as you put up more buildings the blank areas around the taxiways tend to increase. We still have absolute coverage of the runway.
And there is a super new whizzo one coming soon.
This will have more than one source so should avoid blank areas.