I use to have my 315 mounted above the caravan on a pole.
Unfortunately on sites we regularly visit, we encountered a reduction in signal.
Apparently according to the site regulars, the local analogue signal had been reduced, presumably to push people onto digital?
But also the digital signal wasn't yet up to full power.
Consequently the statics had all been and bought high gain aerials. So frustrated by varying quality, which the weather or a different pitch, was throwing up, i now have a high gain ariel on the pole, this has sorted the problem.
The ariel i have is only about 2' long(wide band) and has a mast head amp, the short length makes it good in the wind.