electromagnetic radiation interference?

can a em wave cancel out another em wave, like a radio signal canceling out another and not when they hit the antenna because i know that can be done but can they cancel while still in-flight

i was reading about cell phone jammers and wondered how they blocked the signal exactly

4 responses on “electromagnetic radiation interference?

  1. damex

    yes as I read in quantum physics.That is why em are called waves an particles because they cancel each other.

  2. gp4rts

    An electromagnetic wave can cancel another wave. The condition for complete cancellation is the two waves are the same frequency and 180ยบ out of phase. The dark fringes seen from slit diffraction are examples of wave cancellation. However, cell-phone jamming does not depend on wave cancellation, as that is too hard to control. Instead, the jamming transmission in interferes with the reception of the main signal by overpowering it. The cell phone then cannot decode the signal. The jamming signal can be made broadband so as to cover a large range of frequencies.

  3. socother

    They can cancel out, not fully but to the point where it’s difficult to use them. The interference does vary with the location.

    I don’t know how cell phone jammers work, but I think they send out EM waves within a range of frequencies and those waves have a higher amplitude than the desired waves.
    It’s like you want to listen to someone talking, but people with high and low voices speak very loud around you. So, you can ‘hear’ that one person, but not really.

  4. Leo H

    yes, there is a phenomena called picket fencing common to FM radios, you may have noticed that when you stop at a light in your car the FM station fades, bu if you pull ahead a couple of feet it comes back. this is because you have received a direct and a reflected signal that are out of phase and a small movement, on the scale of the FM wave length, changes this phasing

    as for cell phone jamers they just swamp the signal with a stronger one

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