Remember, we are talking about microwatts per square meter as the signal levels we are talking about harvesting. I didn't read the article, but I am sure that they were not talking about powering transmitters that would have to generate as much as 100 mW of RF power. What one of the other posters mentioned was that they were talking about powering extremely low power device.

Bill Gill

C is not the speed of light in a vacuum.
C is the universal speed limit.