Ah yes STx...that reminds me, Airport Information, was one of the so called Incremental stations
for Gatwick and Heathrow, was on same Chan as KCBC 1584kc, The Carfax was on 526.5kc (See above)
https://en.wikipedia.org/wiki/Airport_Information_Radio

Do you know STx...if Alan B has done any recent simulations on the 5 mast array ?
after your field measurements, showed up the Null to NW ish direction (Northampton bearing) ?

I should think, there is better software nowadays than EZNEC to do simulations/ optimising of
antennas, without copying your model, every time and altering it to see what effect it had
But EZNEC is good, once you got your model right, amazing 3D display of polar diagram

Rod Watts