[Outland]

"limited knowledge of electronics, eh?"

Hardly. I am an electronic engineer by profession. Ask, rather than assume.

I challenge you to describe one item that uses an antenna resonant to any part of the EM spectrum that can gather enough energy to perform actual work without being amplified with another external source of power.

And let's leave out those old science fair air-powered radios that require headphones to produce a weak amount of audio.

[AZLiberty]

Very few radio receivers (if that’s what you’re referring to) try to use a signal from a transmitter as powerful as the sun.

I’ve heard tell of people living next to 50,000 watt antennas picking up radio signals on their dental work. Does that count?

[Barry Goldwater]

Try looking here:
http://en.wikipedia.org/wiki/Rectenna

and here:
http://www.techbriefs.com/content/view/1981/32/

and here:
http://www.nrel.gov/docs/fy03osti/33263.pdf

and here:
http://charon.colorado.edu/Microwave/papers/2000/EuMC_JHnlBP_00.pdf

and here:
http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel1/2220/6808/00274732.pdf?arnumber=274732

and here:
http://sciencelinks.jp/j-east/article/200017/000020001700A0495811.php

and here:
http://adsabs.harvard.edu/abs/2003AIPC..664..292A

and here:
http://findarticles.com/p/articles/mi_qa3957/is_200008/ai_n8914804

and here:
http://ece.colorado.edu/~pwrelect/Seconddraft/paper_archives/efficientbroadbandrf_apr2005.pdf

The problem in the original article are the rectifier diodes for use at infrared wavelengths, of which the article makes no mention. In metals, such as gold, the extinction length is about 1.5 wavelengths for IR. Semiconductor diodes will not work so other types are needed.

[SC Swamp Fox]

I challenge you to describe one item that uses an antenna resonant to any part of the EM spectrum

I can't think of one, but has anyone ever built a 10 million element array before, particularly one tuned to the biggest source of EM available.

I'm skeptical as well. I believe the challenge is gathering and storing anything from the array. Additionally, they make the claim that they "might" be able to achieve very high efficiencies, but how much IR is available? A 95% efficient 1m square panel may not keep my watch running.

[junkman72]

did you even read the article???

[pa_dweller]

I challenge you to describe one item that uses an antenna resonant to any part of the EM spectrum that can gather enough energy to perform actual work without being amplified with another external source of power.

Would passive RFID tags qualify?

[whd23]

I challenge you to describe one item that uses an antenna resonant to any part of the EM spectrum that can gather enough energy to perform actual work without being amplified with another external source of power.

H₂O molecules in a household microwave oven.

What's my prize?