Good Day...
Have you consider on of these?
http://www.hdtvprimer.com/ANTENNAS/DAT75.html
I almost bought one but a bit too pricey. I don't know what RF Freq range most of your UHF stations are in but this might be a good choice.
Also do not discount the tigerbangs "deep fringe" solution. My brother used it here in the States are it works wonderfully.
I install a new antenna today. (See post above) Very Happy.
Can you give us a bit more detail....might help.