Guy's suggestion looks good to me providing you need less than 12 ft of cable at either end to connect.
Wireless range is just plain odd. On one hand, I've been able to regularly "see" several neighboring networks that were, some oof them, probably in excess of 100 ft away/ On the other we sometimes have trouble talking to the printer down the hall. Since you've tried range extenders with no luck (I just read some underwhelming reviews "extended sweet spot range from 20 to 30 feet") and since my one best guess about the problem, the aluminum siding, cannot be realistically changed, I thought I'd leave a link to a "war driving" site. War drivers are the folks who go around looking for open wifi lans and use them to surf the internet. Doing this on some wireless lans can apparently get folks in big trouble these days if they get caught. The technology, however, is interesting.
http://www.wardriving.com/antenna.php
Just be smart about downloads and other linked sites.
good luck
relayer