How high to mount your aerial : 6ft or 12ft ?
How high to mount your aerial ?
Well that’s a big question.......
Generally speaking the higher the better, at least that’s the usually case with aerials.
But not always.
In the past we’d done tests on aerial heights for installations mounted on roofs, but what about at the kind of height the average boat or caravan owner would have his antenna ?
Whilst checking up on the accuracy of testing aerials at 6ft (it is accurate by the way.....) I also compared the signal at the test site at 6ft and 12ft, which is about the sort of heights that boaters and caravanners use.
I measured the received signal off three transmitters : Emley Moor, Bilsdale & Belmont. The transmitters were in three different directions, and there was "line of sight" to all of them.
An increase of 4.1dB (which is signal rise off Emley Moor) for raising the aerial only 6ft is huge. To put it into context that’s not far off the increase in signal you’d get by swapping a little 3ft 6in DM Log for a big 5ft 3in DY14WB ! Even the 2.3dB increase off Bilsdale is a significant improvement.
Off Belmont there was actually a huge 4.8dB decrease ! Why this should be when there was nothing between the aerial and the transmitter (albeit 65 miles away), well your guess is as good as mine. It’s a perfect example of RF being a black art.
Note the spread of results, the averages can give a misleading impression (as is the case so often). Some signals off Belmont wouldn’t be that much different, but one in particular was 8dB down. Now that is massive amount, but, of course, even with that reduction the TV may still work perfectly if the signal strength was high enough, which at this location it would be.