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sophiecentaur is offline
Dec9-12, 12:52 PM
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Quote Quote by mfb View Post
Lasers do something similar. If you want to use electronics to generate those fields, you are (currently) limited to lower frequencies like Masers or RF cavities.
Lasers etc. are still quantum devices, though and the emission is from atoms - hard to know what they are doing when radiating, in terms of the fields.

There are all sorts of things that you can do with fields at (the much lower) Radio Frequencies by manipulating the actual fields involved rather than taking the photon approach.
It is possible to take a coil and two flat plates or a short dipole (both structures significantly smaller than the wavelength in question) and feed them with the same signal in appropriate phases. They will produce oscillating (predominantly) magnetic and electric fields, respectively in the near vicinity. However, each one, taken on its own, will also produce the 'other' field and will radiate in its own right, when you look in the 'far field'. But by using both together, you can produce the equivalent of the far field wave closer to the structure and you will actually be able to radiate more power than each element taken separately if they are both small compared with a wavelength.