Could be a laser beam used as an antena to detect EM waves? 1

[dapifo]

Could be a laser beam used as an antena to detect EM waves?... If yes how it could be designed the whole system?

 

[VEBill]

Start with the short answer: No (as far as I know).

Clarification of your question: antennas do not "detect", they only convert between conducted and radiated. To detect one needs a detector.

Background - a laser beam is light, and light is just another wavelength of EM. The medium (vacuum, air) will be linear under any reasonable conditions. Therefore the EM signal will remain within its frequency spectrum, and the laser beam will remain on its precise wavelength. If one EM signal reacted to another, the EM spectrum would be a mess. So a laser beam will not react to (detect) an EM signal.

A laser beam is not conductive (unless it's so strong that it ionizes the air, but then it would punch holes in walls). So it won't be an antenna.

Somewhat related: I recently saw an article about how the plasma within fluorescent tubes (on) is quieter (RF) than expected and can be used as RF conductors and antennas. Ions, not laser beams.

All above "as far as I know".

 

[dapifo]

Thans very much...I was a very good and clear answer and info.

 

[VEBill]

More: US Patent 3,404,403 is for a "Laser Beam Antenna".

But it's from 1966 and (as far as I know) has never been used in practice. It involves ionization of air.

 

[biff44]

There are previous papers where a fiberoptic cable is coated with something (like thin silver layer) and it responds to a microwave signal by causing an optical phase shift. That is using a laser, but not freespace.

There would be plenty of non laser methods, like using neon lightbulbs, various materials that alter their optical properties in the presense of microwaves, etc.

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