I assume you are in a portacabin or low level building?
It's about as bad as it gets......
couple of thoughts....
have you tried re-tuning
we recently moved house ... I thought pointing at the same ariel ... (only 2 miles down road) but no ... all tellys needed re-tuning.
I'm using an amplified indoor (digital) ariel which is mains powered - and it's realy good ... (but that doesn't help you).
so they do work in some circumstances
how about a local TV shop ... perhaps you could strike a deal - try before you buy .... to find one that works