Legal situation?!? You're creating a matched impedance point in space.

RF energy harvesting is a bit of a hot topic, there are a number of modules on the market atm. Just search for it on mouser or farnell to get started.

Thanks btw for that LED schematic, so simple. I'm currently tuning a harvester around a BQ25504 and super caps. I'll give it a test next week.

http://uk.mouser.com/Embedded-Solutions/Energy-Harvesting-Mo...

This one contains other energy sources as well:

http://uk.farnell.com/jsp/search/browse.jsp?N=2002+225290&Nt...