As I understand:

  • Accelerating electrons generate electromagnetic waves.
  • An emitting antenna have an alternating current (electrons are moving) which generates an electromagnetic waves.
  • The electromagnetic waves reach the receiving antenna and makes the electron inside move.
  • Greate, the communication is done.

However, since the electron in the receiving antenna are moving too, the receiving antenna is generating an electromagnetic wave too. How is this not affecting the incoming wave? Does it have a different wavelength?

  • $\begingroup$ the answer is "yes" if you put them close enough to each other. how they interfere with each other depends on their geometry and not on what "frequency of operation" that the electronics connected to them might be operating on. $\endgroup$ – robert bristow-johnson Nov 27 '15 at 7:02

Yes they both operate to different frequencies.

Two-way radios can be designed as full-duplex systems, transmitting on one frequency and receiving on another, this is also called frequency-division duplex.

How is this not affecting the incoming wave?

Source : Wikipedia

A radio transmitter is an electronic circuit which transforms electric power from a battery or electrical mains into a radio frequency alternating current, which reverses direction millions to billions of times per second. The energy in such a rapidly reversing current can radiate off a conductor (the antenna) as electromagnetic waves (radio waves). The transmitter also impresses information such as an audio or video signal onto the radio frequency current to be carried by the radio waves. When they strike the antenna of a radio receiver, the waves excite similar (but less powerful) radio frequency currents in it. The radio receiver extracts the information from the received waves.

As it says the incoming wave excite but with less power, so it do not effect other incoming waves..

The best example you can find is Transceiver using RF Module

This article can explain different frequency used difference Why do you need two antennas in a radio?


All of these oscillations have the same frequency, so the EM waves have the same wavelength.

Maxwell's equations are linear, and air is a linear medium, so EM waves don't interfere with each other. You can point a laser pointer across the room and it won't affect all of the other light rays flying around the room. So the incoming wave is not affected by anything created by the receiving antenna.

Any emission by the receiving antenna (scattering) is really small as compared to the wave coming from the transmitting antenna.

Things are a bit different if the scattering antenna is really close to the transmitting antenna. This is the basis of a beam antenna (https://en.wikipedia.org/wiki/Directional_antenna).


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