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So wireless router broadcasts a signal and then your device searches. So what actually happens when the photons 'meet' it's kind of like saying, 'ah your one of us, so we will follow you, show us the way'

It's so bizarre, how do photons connect during wireless connection?

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    $\begingroup$ Photons do not meet mid-air and just recognize each other. What your device does is detect incoming electromagnetic waves. It does not send out waves which then meet other waves at some point in space and miraculously recognize each other. The antenna in your device detects signals and transforms them into electrical pulses and so on.. $\endgroup$
    – Hasan
    Jan 30 '14 at 12:38
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    $\begingroup$ Wireless networking is a form of RF communication identical in many ways to radio communications. The frequencies are much higher (GHz instead of MHz and kHz) and this, together with some other technological innovations, allows us to transmit much more information than just one audio stream. $\endgroup$ Jan 30 '14 at 15:46
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In principle the wireless router is sending out radio waves (photons) in all directions. Some of those are picked up by the antenna in your phone or laptop, which turns it into an electrical signal.

It's similar to broadcasting in public radio: the broadcasting station is sending out radio waves in all directions. Your kitchen radio doesn't transmit anything, but instead it picks up all waves that hit its antenna, and then tries to filter out the frequency/channel you want to listen to. The broadcasting station doesn't know where your radio is - it just transmits waves in all directions. And your radio also doesn't know where the broadcasting station is - it receives all sorts of waves from all directions. Then it's just a matter of electrically/electronically filtering out and amplifying the desired wave.

Same goes for routers: they receive all sorts of waves from nearby routers (and other sources), but filter out only the signal that has the correct SSID, for example.

It's important to see that photons don't interact - two waves can perfectly go through each other. The signal is induced in the antenna because the electric and magnetic components of the radio wave make the electrons in the antenna move. And moving electrons are a current - something electronic components can process and the device can "understand".

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In the sense of routers (transmitters and receivers) it is preferable to consider the wave-model for the electromagnetic field.

The router has an antenna that, due to how it is shaped and how the current running through it is modulated, creates an electromagnetic field that propagates depending on direction and construction of antenna. For routers the ideal case would be to have an isotropic antenna (one that radiates equally in all directions) but this antenna is difficult to construct (a perfect isotropic antenna would be a metal sphere, but it has to be driven by current so this would destroy the perfect-sphere aspect of it) so wifi-routers are not radiating isotropically, but they're designed to be close to it.

When this electromagnetic wave produced by the router hits a wifi-receivers antenna, a current is induced in it. The phase and amplitude (and possibly frequency but this is rarer) of the electromagnetic field depends on the current running through the transmitting antenna, and this also creates a corresponding current in the receiver. The same current that is running in the transmitter is induced in the receiver, with more noise and lower magnitude however.

Your understanding of it as guided photons is inaccurate, they are not guided at all by each other but they are emitted in a directional pattern. These are waves that are travelling, and as any other wave, they surrender to the theory of superposition so they maybe interfere with each other in different spatial locations, but they are not "drawn" to each other in any way.

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  • $\begingroup$ Note that coherent isotropic antennas do exist, they're just hard to build. If you relax the coherence requirement, it's even easier - the Sun is one example. $\endgroup$ Apr 5 '19 at 7:38
  • $\begingroup$ updated @EmilioPisanty $\endgroup$
    – DakkVader
    Apr 5 '19 at 7:45
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I'm not 100% sure, but I suppose photons are identified by its frequency.

WiFi routers have usually 12 or 14 channels, whose frequency depends on the local laws for telecommunications. They are supposed to be the only photons in each channel.

Any photon of a different frequency just will not be absorbed by the antenna.

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  • $\begingroup$ Welcome on the physics.SE ! You actually did not answer the question, but rephrased it. $\endgroup$
    – Tom-Tom
    Jan 30 '14 at 13:03

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