Unexpected poor reception after house move

I'm new to this forum, so hello to everyone.

Recently moved home and the coverege using the same hardware set up is inferior at the the new house. The new house is around about the same elevation as the old one and the surrounding buildings, terrain etc are very similar. The antenna at the old house was mounted in the loft. I got 360 degrees coverage, albeit weaker in certain areas of the sky. I was picking aircraft up over 250 miles away iin parts of the sky.

At the new house I had the antenna in the converted loft initially. I was surprised to find I wasn't getting any contacts from one half of the sky. On the other side I was getting quite good hits, although not getting ones over 200 miles as at the previous house. Because of the definate split of two halves, coverage on one side nothing on the other, I decided it could be the foil insulation used in the loft conversion ceiling.

I have now mounted the antenna on a chimmney stack above the roof outside and guess what, still the same type of reception. Reasonable in one half of the sky, nothing in the other half.

Has anyone got any ideas why this might be happening?

Thanks