Sunlight is electromagnetic radiation, of very short wavelength. Can we make arrays od tiny 1/4-wave antennas 9with equally small rectifiers), and get DC directly from the sun? I know these things would have to be very small, but using nano-technology, is this feasible?
I know that solar cells exist-but they are very expensive. Wheresas an array of micro-antennas would make lost of power, at an almost 90% conversion efficiency.
Has anyone ever tried to build these?
1/4 wave antennas for the visible spectrum? I don’t think that part of the EM spectrum works quite that way but assuming it did and assuming you could build such a decice and that any kind of electrical diode worked at that frequency why do you think it would be 90% efficient?
Agreed. If you shine light on a piece of wire does a current flow in the wire? The wave hardly penetrates the wire at all. Even ignoring all quantum effects and pretending like it is just another em wave, infra red at a wavelength of 700 nanometers has a 3 skin-depth penetration into a copper wire of about 10[sup]-6[/sup] meters. Shorter wavelengths, were most of the energy in the sun’s spectrum is, would have less penetration. In effect it appears that the great majority of the solar radiation is simply reflected off the wire.
This idea got worked on and published a few years back. This part of the electromagnetic spectrum does indeed work like you hope. Metal looks reflective in pieces bigger than the wavelengths precisely because it conducts and therefore generates mirror image waves to cancel the originals.
IIRC the bigger problem was creating diodes that work fast enough.
I knew that.
I seem to recall an article a few years ago that looked at the molecular structure of chlorophyll and concluded that the chlorophyll molecule was basically a dipole antenna. However, it was connected in such a way that the ‘output’ was a chemical reaction, rather than free electrons and a voltage potential.
I may be seriously garbling that, though.
ISTR that, in his story The Roads Must Roll, Heinlein posits the ‘Douglas-Martin sunpower screen’ (an inexpensive solar panel) as using dipole antennas scaled to light wavelengths.