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I'm curious how signal dispersion works. When I access a site on my computer I am sending a request to my router to then get some information from some server.

  1. Does this signal request just completely fill up the air around me until something picks it up or is it a straight shot to the router because it knows where it's going?
  2. And what if it doesn't find the router? Does the signal just disappear or disperse into the ether?
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    \$\begingroup\$ The same thing that happens to unreceived radio broadcast signals. They propagate outwards until they're absorbed by something and heat it up. Or until they alert the little green men to our presence and they come to Earth to steal our women. \$\endgroup\$ – The Photon Apr 19 '17 at 5:22
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    \$\begingroup\$ ABORT MISSION, @ThePhoton FIGURED US OUT \$\endgroup\$ – Marcus Müller Apr 19 '17 at 6:41
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    \$\begingroup\$ No matter if the signals are received or not, most of the signal energy is lost. But at some distance when the signal is much weaker than the noise level around, the signal is not detectable in praxis. The signal could not be received there anymore using standard equipment. \$\endgroup\$ – Uwe Apr 19 '17 at 8:27
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Radio/"wireless" signals are actually "light waves" ... when a signal is sent from an antenna, the same thing happens to the signal as happens to the "signal" (light) from a light bulb when you turn it on.

It moves away from the signal source in all directions, and continues moving until it's absorbed by something, or bounces off of something & starts moving in another direction.

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  • \$\begingroup\$ So the data packets that are sent out are really just an infinite number of the same packet? \$\endgroup\$ – Michael Rader Apr 19 '17 at 5:37
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    \$\begingroup\$ Well, technically not quite infinite, but you get the general idea. The data is sent/received by changing the wavelength ("color"), amplitude (brightness), and phase of the signal being sent (or detecting the same in the received signal) and any receiver that gets struck by part of the "signal waves" could, in theory at least, decode it, but as there are a set number of photons in each transmission (usually billions+), it's not technically an infinite number of copies...just more than I'd care to count/calculate. ;) \$\endgroup\$ – Robherc KV5ROB Apr 19 '17 at 5:48
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    \$\begingroup\$ In principle, it's no different to you standing in the middle of a large field and shouting "HELLO". Someone may hear it and shout back, several people may hear it and shout back or maybe nobody hears it or those that do ignore it. None of that stops it carrying on outwards until it fades away. \$\endgroup\$ – Finbarr Apr 19 '17 at 8:26
  • \$\begingroup\$ One of my profs once asked a student who didn't have an answer for: "why have electric railways just one overhead wire if there are always two poles" whether he thinks that the electrons collect underground and are digged up in so-called "electron mines" to produce electric energy. Perhaps this applies to electromagnetic radiation, too. After all, there's also "electro" in its name. ;) \$\endgroup\$ – Gerold Broser Apr 19 '17 at 22:29
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Look at the water waves. Same phenomena from a Transmitter of radio energy.

Place a stick in the water, of length 1/2 the spacing of the water waves, and that stick maximally responds to the waves. Right around the stick. But the rest of the wave energy....just keeps spreading and dissipating.

In radio, we prefer wavelength/2 antennas. Best sensitivity for simple use of copper. Lotta articles out there on antennas.

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