I did this experiment in February 2009. This device was invented to detect / collect "radiant energy" and convert it into electricity it was patented by Tesla in 1905 original patent: http://keelynet.com/tesla/00685958.pdf
My device not collect "radiant energy", it collect static electricity I just wanted to keep the name given to it by Tesla.
I explain how I built it, the results that I obtained. I hope that someone can improve it and get better results
This is a presentation video with a brief explanation of the operation at the end, follows the full explanation and test results on this Instructablehttp://www.youtube.com/watch?v=gr5F2e595wo
The collector in aluminium collects the electrons of the air ionized, it work even with the passage of the clouds (if the air is dry), reached a sufficient charge it spark on candle and circulates the current in primary high-voltage of a injection coil, the secondary is connected via a diode and a small condenser, the small instruments notes the achieved energy.