David Aldridge wrote:

even if it's 'get a
professional'. (in which case how much do you think that might cost?)

Get a professional. They'll advertise in the classifieds in your local
paper.

I got a firm to run an FM spur to my bedroom (I'm a Radio Four junkie)
and they stung me 30ukp. Obviously your situation is more complex,
needing a new aerial (replacing, presumably?), so they'll advise on
specification and do the job for you.

It's not much help, but hth.

--
Ben Blaney
GSF1200 VFR800 CBR600 CD200
"We stopped only for fuel"