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Remote Control + Head = further distance?

  1. Sep 5, 2005 #1
    Remote Control + Head = further distance???

    huh?
    has anyone else noticed this? i'm sure you have?
    has anyone got an explanation for it?

    like... when you put your car remote, you get about 10ft more range from it... or a garage door remote, about another 30ft when you put it against your temple.

    i'm sure this has been asked before, but i cant find the answer...
     
  2. jcsd
  3. Sep 5, 2005 #2

    Pengwuino

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    .... ive never put remote controls up to my head so "huh?" is about right for me.
     
  4. Sep 5, 2005 #3

    Chi Meson

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    I heard of a possible explanation via NPR's "Car Talk": It is not so much that you put the remote next to your head, it's that you change the orientation of the remote. If the sending antenna inside the remote is in a horizontal position, but the receiving antenna in the garage door opener is oriented vertically, the signal will not be received with as much intensitiy as when the two antennas are similarly alligned.

    This is only what I heard, and the two guys are MIT graduates (tho they act like idiots). But I can't think of a better explanation, and I really really really don't believe the head (with a maximum diameter of 25 cm, tops) can have any amplifying effect on a radio wave that is tens or hundreds of meters in wavelength.
     
  5. Sep 5, 2005 #4
    to: Pengwuino
    try it... it works! obviously not IR remotes, but RF remotes
     
  6. Sep 5, 2005 #5
    to: Chi Meson
    your MIT grad's might be idiots because although that makes sense, it surely wont add between 3-30ft extra range?
    i drive down the street, its a curved street... and it never opens the garage door before about 20m unless i put the remote to my head... regardless of the orientation of the remote...
     
  7. Sep 5, 2005 #6
    + your common garden-variety RF remote operates at 433MHz if i'm not mistaken. if i am mistaken, slap me!
    A frequency of 433MHz has a wavelength of 69.236cm... and my head's definately not that big!!!
     
  8. Sep 6, 2005 #7
    what about your brain or undiscovered telekenetic abilities

    i know this may sound crazy but evolution may create these ways we can manipulate space time. Mabey this is one of the first cases of it. Well a radio wave is composed of relativly small particles so mabey could be amplified by our own intentions in our consciousness
     
  9. Sep 6, 2005 #8

    ZapperZ

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    Please do not turn this into a crackpot theory or it WILL be locked! Read our PF guideline that you have explictly agreed to before posting.

    Zz.
     
  10. Sep 6, 2005 #9

    Chi Meson

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    I have a remote garage door opener too. I have never gotten better range by pointing the thing at my head. I have gotten better range by changing the orientation (never 30 feet tho). I believe there to be some other explanation that is rational and scientifically supportive.
     
  11. Sep 6, 2005 #10
    Speaking as an antenna engineer, your head will affect the radiation pattern of
    the remote. It may end up concentrating the signal in some direction and if the
    receiver is on the edge of detection it will get enough of a boost to operate the
    door.
     
  12. Sep 6, 2005 #11

    Chi Meson

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    By radiation pattern are you referring to "near field" radiation, etc?
    And can your skull act like a parabolic mirror for radio waves? I'm very curious as to how this could happen. Could you elaborate?
    TIA
     
  13. Sep 6, 2005 #12
    re: Chi Meson
    i dont mean point it at your head, i mean hold it against your temple

    re: "And can your skull act like a parabolic mirror for radio waves?"
    that's what i thought the answer was... just how it does that, i dunno :/
     
  14. Sep 7, 2005 #13

    Chi Meson

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    As far as I know, it couldn't. Since radiowaves, at there shortest, are meters in length, the size of the skull is far too small to cause significant reflection, regradless of the non-parabolic shape.

    It did just occur to me that since touching the antenna on a TV, for instance, will enhance reception, perhaps touching the remote allows the body to become an extension of the transmission antenna. This means it is not the head that does it, per se, but the whole body.

    Anyone? Have the Mythbusters taken this one on?
     
  15. Sep 9, 2005 #14
    Not like a parabolic antenna. More like a one-element director/reflector
    pair. Look up Yagi-Uda dipole arrays.
     
  16. Apr 3, 2007 #15

    Jed

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    One of the main components of any radio tuner is called the "LC Tank" or "LC circuit". http://en.wikipedia.org/wiki/LC_circuit It's a very simple circuit and the frequency it resonates to (is tuned to) is given by:

    f = 1/(2*pi(sqrt(LC)))

    You can't really have much effect on "L" the unless you come into direct contact with the circuit. "C" however is the capacitance and will be affected by conductive bodies close to it. Proximity relationship is exponential... that is 1" away is far more of an effect that twice the effect from 2" away. So as your body comes into contact with the plastic body of the fob the value of C has now changed.

    This effect is often experienced in a noticeable way when trying to tune a radio to a weak signal. Every time you get it just right you move your hand away and it goes out of tune. You can often beat this problem by tuning the radio slightly off station... when you remove your hand it will detune it to the right frequency.

    Engineers who manufacture these fobs will make them slightly detuned knowing you need to put your hand into contact to operate it. Putting it close to the mass of your body, your head or your torso, increases this effect thus increasing range.
     
    Last edited by a moderator: Apr 3, 2007
  17. Apr 3, 2007 #16
    Perhaps raising the remote to your temple gives it an extra 1-2 feet of height, which would put its LOS closer to your garage receiver, but this is opposite to your car example where most receivers are (waist high?).

    Also, another random possibility is there is much street level radiation noise 3-4 feet above street level, but for whatever reason(s), 5-6 feet has much less noise that would interfere with your remote's signal.

    That's all I can think of.
     
  18. Apr 4, 2007 #17

    Jed

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    The simple test for this is to hold the remote at the same height and orientation but not near your head. This has no range increasing effect. Similarly you can hold it in the same as normal orientation but against your torso... range will be improved.

    Try these things... I have. I stand by my posit above.

    Jed EE
     
  19. Apr 5, 2007 #18

    So its not an issue of the remote being closer to your head, so much as it is whether the remote is close to your body. I don't see a big mystery to this. If your body is a better conductor than air, which it is, the closer your move a remote to its central bulk, the higher the amplitude of your signal will be.
     
  20. Apr 6, 2007 #19

    Jed

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    Why?

    You see this claim that you make is true... but why? If you don't know why this is a big mystery... to you anyway.

    The answer is above.
     
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