The Harvester. Sounds like the title of a Steven King novel. Not quite. The term “power harvesting has long been given to the process of acquiring useful power from otherwise wasted energy sources. However, in this particular application it is the name given to a uniquely innovative system that provides power to electronic devices virtually free. The theory has been known for years: a vast amount of energy flows in the ether simply from the existence of random RF radiation over a vast spectrum. The engineering challenge, of course, has been focused on efficient ways to detect, capture and store (i.e. “harvest) that energy for useful work. The enablers that have emerged to solve the harvesting engineering challenges are nanotechnologies along with fast, efficient microprocessors running comparatively simple but cleverly designed scanning and switching logic algorithms. Here's how it works.

The heart of the harvester is an active antenna constructed of carbon alloy nanotubes arranged in a fractal configuration. Electrically, the antenna consists of multiple dipole arrays that can be electronically switched to achieve resonance from 1 KHz through 1000 GHz. A sensing algorithm rapidly sweeps the antenna geometrically through that spectrum range, locking on detected electromagnetic sources. The aggregate energy is then rectified and stored in a capacitor for use by the host application and, of course, for powering the harvesting process itself.

Efficiencies of over 80% have been achieved with a sustained constant current output of several microamps. Applications have ranged from remote static sensors to security detectors. By next April 1, expect to find smart phones harvesting the spectrum and even powering themselves.

Ed

April 1, 2011