DIY WiFi antenna (to increase reception)

Discussion in 'Linux Networking' started by gaikokujinkyofusho, Jun 9, 2005.

  1. gaikokujinkyofusho

    Unruh Guest

    You remember wrongly. 2.4GHz has a wavelength of about 10cm. It is a factor
    of over a thousand from what one would call IR.

    The propagation of these waves does not have very much diffraction, nor
    does it reflect off the ionisphere. It does reflect off of lots of other
    stuff however.
    And "line of sight" means light, since that is what we see with. And in
    this case as I said, the absorption of light and microwaves is very
    different. That you cannot see it does not mean that the waves cannot get
    to you.
     
    Unruh, Jun 11, 2005
    #41
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  2. gaikokujinkyofusho

    Unruh Guest

    No. The term is absorber.

    Precisely.
    And also true of light.


    And you know this how? You did experiments in his house?
     
    Unruh, Jun 11, 2005
    #42
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  3. If you knew one tenth as much about the subject as you pretend to,
    you would be aware that Maxwell's equations govern the propagation
    of electromagnetic waves.
     
    Timothy Murphy, Jun 11, 2005
    #43
  4. gaikokujinkyofusho

    James Knott Guest

    Oooopppsss. Looks like my math is off a bit too. 10 centimetres is about
    10,000 microns. So that means you're only off by 2 orders of magnitude.
     
    James Knott, Jun 11, 2005
    #44
  5. gaikokujinkyofusho

    James Knott Guest

    I live in a condo, with concrete between me and the garage. Also concrete
    between the stairs and garage.
    I used the term "relatively", in that the signal passes through those
    materials, with some unknown degree of attenuation. Different materials
    have different amounts of attenuation of radio signals passing through
    them. A signal passing through concrete or drywall will be more
    attenuated, than if passed through air or vacuum.
    Ever hear of loss in fibre optic cable? The glass used in it is far more
    transparent than window glass, so it produces less signal attenuation.
    However, if you have enough of it, it becomes opaque to the signal. There
    is measurable loss in any substance you care to mention. A truly
    transparent medium would have no loss whatsoever attributable to that
    medium. The only thing that applies to, as far as I know, is a vacuum. We
    don't notice the signal loss in spectacles, because they're fairly thin.
    If they were a few meters thick, there wouldn't be anywhere near as much
    light coming through them.

    Incidentally, on a related topic: The U.S. nuclear navy is a result of the
    work done by Adm. Hiram Rickover. Due to certain technical constraints, in
    a sub designed for espionage, they omitted the lead shield, to the rear of
    the reactor and instead flooded the compartment with water. The 13 feet of
    water provided equivalent shielding to 1 foot of lead.
     
    James Knott, Jun 11, 2005
    #45
  6. Perhaps it might simplify the discussion if you stated as clearly as you can
    what you mean by "line of sight".

    To me, if someone says that something works "by line of sight"
    I take it to mean that someone at the receiver
    must be able to see the transmitter.
    Eg Merriam-Webster gives the definition
    "the straight path between a radio or television transmitting antenna
    and receiving antenna when unobstructed by the horizon".

    This is manifestly not true of WiFi;
    my laptop is linked to my desktop in the floor above,
    which is certainly not in my "line of sight"
    as there is a ceiling in the way.

    My original - in fact my only - claim is that WiFi
    will work perfectly well in any normal house or apartment.
    If you prefer me to re-phrase this:
    1.2GHz photons will find their way
    from an access point in the middle of the house
    to anywhere else in it, in sufficient numbers
    to render a good WiFi device completely reliable.

    Have you in fact been in a house or apartment
    where WiFi did not work?
     
    Timothy Murphy, Jun 11, 2005
    #46
  7. gaikokujinkyofusho

    Paul Black Guest

    Isn't 10cm exactly 100,000 microns?

    Paul
     
    Paul Black, Jun 11, 2005
    #47
  8. As a matter of interest, is there something special about 2.4GHz photons?
    Are they perhaps a different shape from 2.3GHz ones?
    Or what about tiny 1.8GHz ones?
    Can they travel in circles?

    Please pass on some of your secret knowledge of the subject.
     
    Timothy Murphy, Jun 11, 2005
    #48
  9. Is there a subject called "path engineering"?
    What exactly does one study?
    Does it have something to do with Feynman integrals?

    You seem to be saying that in this esoteric discipline
    the term "line of sight" has a different meaning
    to that attached to it in normal speech,
    where one says that there is a line of sight from A to B
    if someone at A can see B and vice versa,

    If in fact the term has a special meaning in your subject
    (as a matter of interest, are you a "path engineer"?)
    then when writing in an arena like this open to ignoramuses like me,
    I would suggest that you add some qualification like
    "line of sight (as understood by path engineers)"
    to avoid confusion.
     
    Timothy Murphy, Jun 11, 2005
    #49
  10. gaikokujinkyofusho

    James Knott Guest

    Of course, here we're talking about WiFi, which uses 2.4 GHz photons. ;-)
     
    James Knott, Jun 11, 2005
    #50
  11. gaikokujinkyofusho

    YouCanToo Guest

    A google should could of provided the information.
    well lets see 802.11 starts at the freq of

    2.412 GHz for channel 1 and 2.417 GHz for channel 2 and so on. There is
    is only 5 MHz separation between the center frequencies

    There for if you are at 2.3 Ghz or the 1.8Ghz that you mention above.
    Who knows what you would be talking to, but it sure the hell would not
    be 802.11a,b or g wireless.


    Also it would be *ELECTRONS* not photons!
     
    YouCanToo, Jun 11, 2005
    #51
  12. gaikokujinkyofusho

    Stan Goodman Guest

    No, that is not manifest. The ceiling is transparent at the wavelength of
    interest.

    The dictionary is talking about a different thing entirely. It is relating
    to propagation of much longer wavelengths and much longer transmission
    distances -- comparable with the dimensions of the planet. It is making a
    distinction between wavelengths that see the surface of the earth as a
    waveguide, so that they will follow the curvature of the earth, and those
    that do not.
    Even more accurately: In your house, with its geometry and materials, WiFi
    works for you. You can't generalize beyond that. If you had limited your
    claims to this, and avoided ridiculing principals that you do not
    understand, this thread would have died a well deserved death two days ago.
    You are becoming even more careless with your statements. In any house or
    other place, WiFi will do something. Over what distances and around what
    corners are, in the absence of actual descriptions, imponderables.
     
    Stan Goodman, Jun 11, 2005
    #52
  13. gaikokujinkyofusho

    Stan Goodman Guest

    I am not sure that you have added anything to what I said.
     
    Stan Goodman, Jun 11, 2005
    #53
  14. gaikokujinkyofusho

    Stan Goodman Guest

    Maxwell's equations are not necessary to explain what I have been trying to
    get through to you.
    I have two degrees in electrical engineering, and have spent a long career
    in the field. But I bow to your intuitive grasp of the physics of
    electromagnetic propagation.
     
    Stan Goodman, Jun 11, 2005
    #54
  15. gaikokujinkyofusho

    Stan Goodman Guest

    I have been trying my very best to avoid using the word "stupid", but your
    paragraph just above makes that very difficult.
    Young Tim: I think he is trying to tell you that the propagation behavior is
    a function of wavelength. Timothy, please go read a book on this subject
    before you belittle people who may just possibly know what they are talking
    about. Photons do have wavelength and behave differently. You may interpret
    this in terms of different shape or even flavor if you like.

    Try too to develop less fuzzy thought processes, because precision of
    thought is everything in engineering. Ask yourself how you can say that you
    are not an engineer, that you in fact know nothing about the field, and then
    turn around and pontificate about it. And give some thought to arrogance --
    it isn't a becoming trait in anyone.

    I don't have the nerves to bear your cocky arrogance. This thread will be in
    my killfile within a minute.
     
    Stan Goodman, Jun 11, 2005
    #55
  16. gaikokujinkyofusho

    James Knott Guest

    Quite so. I guess I've had too much sun (or not enough beer) today. Either
    way, 2.4 GHz is still a long way from IR.
     
    James Knott, Jun 11, 2005
    #56
  17. Close enough for Government work, right?
     
    Floyd L. Davidson, Jun 11, 2005
    #57
  18. gaikokujinkyofusho

    James Knott Guest

    Except in torpedos. ;-)

    Actually, all forms of EM radiation use photons, not just light.

    From http://en.wikipedia.org/wiki/Photon

    "Properties

    Photons are commonly associated with visible light, but this is actually
    only a very limited part of the electromagnetic spectrum. All
    electromagnetic radiation, from radio waves to gamma rays, is quantised as
    photons: that is, the smallest amount of electromagnetic radiation that can
    exist is one photon, whatever its wavelength, frequency, energy, or
    momentum. Photons are fundamental particles. Their lifetime is essentially
    infinite, although they can be created and destroyed. Unlike most
    particles, photons have essentially zero mass, which can be asserted to a
    high degree of accuracy, and accounts for some of their unique properties.
    Nevertheless, because they have energy, the theory of general relativity
    states that they are affected by gravity, and this is confirmed by
    observation."
     
    James Knott, Jun 11, 2005
    #58
  19. Sorry, I must have lost the train of thought.
    Isn't that what you were talking about?
     
    Timothy Murphy, Jun 11, 2005
    #59
  20. The phrase is "line of sight", not "line of microwave".
    In my understanding "sight" refers to the octave of visible light.

    The room above the ceiling is not in my line of sight,
    and it is not in the line of sight of any other normal people either.

    I don't know any "path engineers",
    perhaps it would be in their line of sight.
     
    Timothy Murphy, Jun 11, 2005
    #60
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