Radar rocket science

[What?]

Try a suppression capacitor on your horn terminals to reduce the rf interference generated by the horn.

OK - ya wanna get a bit more technical? All other options have proved fruitless (outside of running an external power source)

[Biff]

Pop into Dickie Smith and buy yourself a cheap ferride filter (or a capacitor). You feed your cables through it (just like the ones you'll fins on some digi camera USB leads etc). Eazy squezzy.

If you follow Ixion's advice ensure you earth the mesh for best results.

What you're experiencing is more than likely an RF harmonic. Filter it out, or buy a better radar detector - like a Bel, as they have some pretty wizzy RF filtering on them in order to avoid false alarms and such like.

[What?]

Cheers Biff. I will go see Dickie in the next few days.
The cage idea went out the window early on - the noise is definitely travelling through the wires, not the atmosphere (although plenty of other noise is).
Interestingly, from reading some Merkin fora, it seems that this issue is not limited to Escorts, and does happen with Bel's as well. 2 different detectors have the same problem on my BM, but neither are effected in my ute (same horn).
Some of the aforementioned Merkins report laser falsing happening (in cages) just under hard acceleration! Also falses caused by window wipers etc.