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Passive long range sensor using radio wave distortions?

  1. Aug 26, 2013 #1


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    Greetings PFers,

    I was thinking about how it would be possible to "scan" something without having visual or physical contact (and without have a superconducting magnet, etc...)

    Lets have this device detect something conductive.
    If a device were to emit an electric field pulse of very short duration, then wait and send out another pulse. The antenna would be surrounded by an array of sensors which detects the strength of an electric field in many, many locations. When the first wave encounters the metal object, the wave front will be distorted because of the conductive properties of the object. Correct me if i'm wrong, but wouldn't the 2nd wave which hasn't propagated outside if the device yet also be distorted? The sensors inside the device would trace the contour of the wave front leaving the device and note any distortions which would be identical to those of the first wave. Utilizing the identical distortions inside the sensor and outside the device, one could effectively scan an object. This sensor wouldn't utilize wave reverberations/ bouncing.

    My biggest concerns is the wave propagation velocity would be too high for current technology to detect. Also, the distortion of the first wave might not distort the second wave because both are traveling practically at the speed of light. Am I wrong?

    An alternative to the above method is to broadcast a pulsed electric field, when the field passes through matter, it's atoms become polarized momentarily. A sensor in the broadcast device would measure the magnitude of the residual electric field using a 3D matrix of sensors with very high resolution. However, the residual field might be too weak to detect.

    I realize this is a long shot...

  2. jcsd
  3. Aug 27, 2013 #2


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    Trying to re-invent the metal detector?

    I'm really not clear about your description and what you are trying to accomplish at the top level that is different than a metal detector.

    I don't think waves distort other waves. I think that is what you are expecting. You can get interference patterns but the waves themselves don't interact, that is, transfer energy between themselves.
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