Hi Fred Bramley, Do you know? if Alan B has done any Computer Simulations on the 5 mast Array??
STx Did an Actual survey, after I checked the road for Overhead wires, that could mess readings up
and sure enough, The STx survey showed a Null North-west ish,..(In line with South of Northampton)
This was prompted by a poster on here, showing levels for most North and West bearings

This shows that, Because the 5 masts are, so near to one another, even with the other 4 feedpoints O/C
the other masts cause directional effects, mainly Nulls, in certain compass bearing directions

Many Years ago, I did Simulations on Lindenblad FM Antennas, for Community stations, Using EZnec
Once you had wrote the "model" you could make several copies, and tweak each one, to see result
Does anyone know, any better Simulation program, than EZnec, that you can tweak to optimise bits
The most involved bit with EZnec, is doing Earthing system, But as BBC spent a fortune, straightforward

It would be good, if One of the array masts could be used, a Full Quarter wave, should be better
bandwidth, than the shorter Back up Folded Unipole, in use now.
as the Quarter wave mast, could produce the same ERP with Less Electric being used

Also has any thought gone into Later on, asking Ofcom for better Bandwidth for 648 ?
It's pretty good now, at around 7kc/s, making other AM stations sound muffled by comparison
I have somewhere, the Exact spacing of the 5 mast array in Feet/Metres/ Wavelength

Rod Watts