Almost any metalic surface you can get up in the air at all will help. You may have trouble with corosion between the copper wire and the foil due to electrochemical potential differences in the metals, so if it works for a while and goes bad that may be why.
You can also try things like metal rain gutters but since the joins between parts of the metal guttering systems will be anything but electrically solid, this may get you more noise than results. the external antenna connections on my old, 1960s Grundig Satelit 5000, are bananasockets, wonder what they use these days. Tom
