[SteveCG]

Well, Triax have called it an '18 element' aerial - but as I've said it is really a 13 element aerial in other maker's nomenclature.

Malvern was originally classed as (one of the few) group D sites (ie ch 48-68), whereas group C (ch 53-65) was more common being one of the three main original groupings. Riggers found that quite a few group C aerials just could not do the top channel - and that this was true even after C was rebranded (but not redesigned) as C/D by quite a few makers. The Malvern Tx did not really provide a signal for Malvern itself - rather it was intended to serve parts of the Severn valley and in particular Worcester City.

The topography of the transmitter with the Hills behind it, and not on top of them, meant that it was possible to receive a very strong signal in Malvern itself but it was highly ghosted. This was because the main beam of the Tx was virtually horizontal whereas significant parts of Gt Malvern were lower in height than the transmitter site and so received less of the direct signal but still received the full Hills reflected/scattered signal. So you see quite a few aerials straining to get an (un-ghosted) signal from distant Sutton Coldfield.

When digital TV first started from the Malvern Tx the digital signals were down in the Group A part of the spectrum - hence the need for a wideband aerial. Also with the analogue ghosting problem up in the Group D part of the spectrum a directional aerial was needed; hence the number of elements on this slightly overkill Triax aerial, for the signal strength at the receiving site of the 'photo.