Electromagnetic waves point to point propagation

[Stanley514]

Is there a theoretical way to force electromagnetic waves transfere energy point to point like electricity instead omni-dirrectionally? I think it might be helpful for looseles wireless energy transfere.

 

[Vanadium 50]

Like a flashlight?

 

[Stanley514]

No. Waves suppose to go for any distance and walk around any obstacles without looses. They need to have some kind of an absolute diffraction. Light could propagate linearly, only.

 

[Vanadium 50]

walk around any obstacles without looses

Sorry, but no.

 

[stedwards]

Use fibre optics. It walks around all kinds of stuff.

 

[Stanley514]

Use fibre optics. It walks around all kinds of stuff.

No. Need wireless.

 

[davenn]

I think it might be helpful for looseles wireless energy transfere.

nothing is lossless, so no, you cannot do it

various RF antennas can be used to beam a large portion of the energy in a particular direction, but there is still lots of spreading out of the energy
and the longer the distance between the transmitter and receiver, the more the signal spreads out

so again, no, cannot be done in a lossless way

Dave

 

[tech99]

Is there a theoretical way to force electromagnetic waves transfere energy point to point like electricity instead omni-dirrectionally? I think it might be helpful for looseles wireless energy transfere.

If we make the source of radiation, say a lens or concave mirror, large in size, the beam will be narrow, but will still diverge due to diffraction. At close distances, however, the beam is approximately parallel, and so the propagation between two mirrors can be nearly loss free. The distance for which the beam remains parallel is the Rayleigh Distance, and is approximately = Diameter^2 / (2 lambda). This distance also corresponds with the furthest point at which a lens or mirror may be focused.

nothing is lossless, so no, you cannot do it

various RF antennas can be used to beam a large portion of the energy in a particular direction, but there is still lots of spreading out of the energy
and the longer the distance between the transmitter and receiver, the more the signal spreads out

so again, no, cannot be done in a lossless way

Dave

As a matter of interest, if the distance between the lenses or mirrors is not too great, it is possible to have a parallel beam and to convey nearly all the energy. In the London Science Museum, they have an optical waveguide consisting of a long pipe with a sequence of lenses, so you can see small objects several metres away. The lenses or concave mirrors must be closer than the Rayleigh Distance, which is approximately,
= Diameter^2/(2 Lambda), and is the maximum distance at which a lens or mirror can form a focus. Optical waveguides like this were proposed for communication just before optical fibre became practicable.

 

[Khashishi]

Vanadium answered this fine with their second post. Just point a flashlight at a photovoltaic cell. Or use a laser if you want something better collimated.

 

[davenn]

Vanadium answered this fine with their second post. Just point a flashlight at a photovoltaic cell. Or use a laser if you want something better collimated.

The OP didn't want to use light

he hinted that he wanted to use RF ... hence why I went into directional antennas