SATTV:

 

I would try a large phased array aerial like this http://www.freeviewshop.co.nz/large-phased-array-aerial-freeview-p-595.html and a new piece of coax as an experiment, move it up and down the pole ( standing height ) to see how it goes, if it works clamp it on and enjoy, if it does not work you will have to try something else.

 

I second this advice. If you're up to the task of getting a new antenna plus bringing it up and taking the old one down, this is what I'd suggest to try. In fact, you probably won't have to raise a phased array antenna to the same height.