Hi STx, Yes an SDR at Northampton would have been perfect, as that was the bearing with the directional problems you tested
Any idea If Alan B has done any Simulations? on the 5 mast array?
Many many years ago, I did EZNEC Simulations for several FM VHF Antennas, Amazing program very good

The main problem, with doing the 'Model' for EZNEC, is the Ground type/ soil etc....
But for the 5 mast array, would be straightforward, as a fortune was spent on the earthing systems there...
It Had to be good, because of the high power it ran then, a poor grounding system would have steamed!

No doubt nowadays there are better programs than EZNEC to use

Rod Watts