WiFi Antenna Location Sensitivity

Discussion in 'Computer Support' started by Jeff Wisnia, Mar 14, 2009.

  1. Jeff Wisnia

    Jeff Wisnia Guest

    I'd like to learn why sometimes moving a wireless adaptor's antenna by
    just a few inches can cause a significant performance difference.

    Ex: Today SWMBO came down to my office (We both work in our own
    business' office.) complaining that internet access on the computer in
    her office was slower than molasses in January.

    We use a Linksys WAP54G router to service the five computers in our
    business. Her computer has a Linksys WUSB54G adaptor plugged into it.

    I gave her my usual reply that MY computer was connecting just fine and
    that she has so much junk and obsolete files stuffed in her computer
    that it probably needs an enema to get its performance back to where it
    used to be.

    That strateguy didn't work, so I hauled my ass down to her office and
    had a look.

    She was correct, internet access on her computer was awfully slow, even
    though none of the other computers in the office were in use then.

    Her computer is the closest one to the router, only about 25 feet away
    with nothing more than a couple of drywall partitions in the way. The
    adaptor software reported excellent signal strength and I checked to
    make sure that the wireless channel we were using was still unoccupied
    by any of our neighbor's wireless systems.

    To make a long story shorter and less boring, I solved problem by simply
    moving the wireless adaptor about four inches sideways on the bookshelf
    it sat on, and her computer instantly regained its usual internet access
    speed.

    I understand how multipath signals can cause RF nulling, but I'd expect
    that the adaptor's software would report "poor signal strength" under
    those conditions. It's the "good signal" report combined with lousy
    performance that has my inquiring mind wondering what's really going on.

    Thanks guys,

    Jeff
    --
    Jeffry Wisnia
    (W1BSV + Brass Rat '57 EE)
    The speed of light is 1.8*10^12 furlongs per fortnight.
    Jeff Wisnia, Mar 14, 2009
    #1
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  2. Jeff Wisnia

    Mike Easter Guest

    Jeff Wisnia wrote:
    > I'd like to learn why sometimes moving a wireless adaptor's antenna by
    > just a few inches can cause a significant performance difference.


    Because it is a radio transmitter-receiver and "all kinds of crazy things"
    can affect the quality of the signal getting around. Including
    interference.

    > Her computer is the closest one to the router, only about 25 feet away
    > with nothing more than a couple of drywall partitions in the way.


    .... and other stuff. Gee, /only/ 25 feet of walls and all of the things
    that are next to and inside walls and in between walls on the floorspace.
    Imagine trying to shine some kind of light-like beam which can penetrate
    some things better than others from some kind of undescribed 'adapter'
    back and forth to some kind of router antenna.

    > The
    > adaptor software reported excellent signal strength


    Sometimes that information is worthless.

    > It's the "good signal" report combined with lousy
    > performance that has my inquiring mind wondering what's really going on.


    3 quick adages. I would rather be wired than wireless. I would rather be
    able to see (with my eyeballs) one antenna from the other than not. And
    you can't trust 'excellent' signal strength to mean excellent clear
    reception/transmission.



    --
    Mike Easter
    Mike Easter, Mar 14, 2009
    #2
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  3. Jeff Wisnia

    Helpful guy Guest

    "Jeff Wisnia" <> wrote in message
    news:gphbhp$ihn$...
    >
    > I'd like to learn why sometimes moving a wireless adaptor's antenna by
    > just a few inches can cause a significant performance difference.


    See Mike Easter's reply.

    Moving a flashlight a few inches can cause it to completely miss the window
    25 meters away.
    RF (Radio Frequency) is not very different. If you could see it like you can
    see light you would immediately see the answer to your question.

    If you want a reliable network use wires.
    Helpful guy, Mar 15, 2009
    #3
  4. Jeff Wisnia

    Helpful guy Guest

    "Helpful guy" <> wrote in message
    news:gphkoj$7ac$...
    > "Jeff Wisnia" <> wrote in message
    > news:gphbhp$ihn$...
    >>
    >> I'd like to learn why sometimes moving a wireless adaptor's antenna by
    >> just a few inches can cause a significant performance difference.

    >
    > See Mike Easter's reply.
    >
    > Moving a flashlight a few inches can cause it to completely miss the
    > window 25 meters away.


    Same with 25 feet :)
    Helpful guy, Mar 15, 2009
    #4
  5. Jeff Wisnia

    chuckcar Guest

    richard <> wrote in
    news::

    > On Sat, 14 Mar 2009 21:14:11 -0400, "Helpful guy" <>
    > wrote:
    >
    >>"Jeff Wisnia" <> wrote in message
    >>news:gphbhp$ihn$...
    >>>
    >>> I'd like to learn why sometimes moving a wireless adaptor's antenna by
    >>> just a few inches can cause a significant performance difference.

    >>
    >>See Mike Easter's reply.
    >>
    >>Moving a flashlight a few inches can cause it to completely miss the
    >>window 25 meters away.
    >>RF (Radio Frequency) is not very different. If you could see it like you
    >>can see light you would immediately see the answer to your question.
    >>
    >>If you want a reliable network use wires.
    >>

    >
    >
    > What you're speaking of is misconceived as "line of sight".
    > What most people mistakenly think of when they believe that in order
    > for the antenna to receive a signal, it MUST be pointed in the
    > direction of the transmitter.


    Wrong. We're talking microwaves here. That's line of sight. That's *why*
    weather radar (and plain radar) works.

    --
    (setq (chuck nil) car(chuck) )
    chuckcar, Mar 15, 2009
    #5
  6. Jeff Wisnia

    Helpful guy Guest

    "richard" <> wrote in message
    news:...
    > On Sat, 14 Mar 2009 21:14:11 -0400, "Helpful guy" <>
    > wrote:
    >
    >>"Jeff Wisnia" <> wrote in message
    >>news:gphbhp$ihn$...
    >>>
    >>> I'd like to learn why sometimes moving a wireless adaptor's antenna by
    >>> just a few inches can cause a significant performance difference.

    >>
    >>See Mike Easter's reply.
    >>
    >>Moving a flashlight a few inches can cause it to completely miss the
    >>window
    >>25 meters away.
    >>RF (Radio Frequency) is not very different. If you could see it like you
    >>can
    >>see light you would immediately see the answer to your question.
    >>
    >>If you want a reliable network use wires.
    >>

    >
    >
    > What you're speaking of is misconceived as "line of sight".
    > What most people mistakenly think of when they believe that in order
    > for the antenna to receive a signal, it MUST be pointed in the
    > direction of the transmitter.
    >
    > Radio signals don't give a damn when or where they get transmitted.
    > Is that antenna on the back of the router a specialized directional
    > unit? Not likely. It is what we call "omnidirectional". That is, the
    > signal gets transmitted in a globular pattern equally.


    Don't worry I know what an omnidirectional antenna is.

    >
    > The receiving antenna, however, is generally of a yagi type. What's a
    > yagi? Look on any roof top and you'll find one. The old standard
    > broadcast tv antenna is a yagi.
    >
    > The yagi aids in pinpointing the source. A more direct line equals a
    > stronger signal.


    I think you should go back to wireless networking school.
    When did you last see a laptop user carrying a Yagi around with it?
    The Yagi antenna is a Japanese invention but not relevant to this thread.
    Helpful guy, Mar 15, 2009
    #6
  7. Jeff Wisnia

    Helpful guy Guest

    "richard" <> wrote in message
    news:...
    > On Sat, 14 Mar 2009 22:06:58 -0400, "Helpful guy" <>
    > wrote:
    >
    >>"richard" <> wrote in message
    >>news:...
    >>> On Sat, 14 Mar 2009 21:14:11 -0400, "Helpful guy" <>
    >>> wrote:
    >>>
    >>>>"Jeff Wisnia" <> wrote in message
    >>>>news:gphbhp$ihn$...
    >>>>>
    >>>>> I'd like to learn why sometimes moving a wireless adaptor's antenna by
    >>>>> just a few inches can cause a significant performance difference.
    >>>>
    >>>>See Mike Easter's reply.
    >>>>
    >>>>Moving a flashlight a few inches can cause it to completely miss the
    >>>>window
    >>>>25 meters away.
    >>>>RF (Radio Frequency) is not very different. If you could see it like you
    >>>>can
    >>>>see light you would immediately see the answer to your question.
    >>>>
    >>>>If you want a reliable network use wires.
    >>>>
    >>>
    >>>
    >>> What you're speaking of is misconceived as "line of sight".
    >>> What most people mistakenly think of when they believe that in order
    >>> for the antenna to receive a signal, it MUST be pointed in the
    >>> direction of the transmitter.
    >>>
    >>> Radio signals don't give a damn when or where they get transmitted.
    >>> Is that antenna on the back of the router a specialized directional
    >>> unit? Not likely. It is what we call "omnidirectional". That is, the
    >>> signal gets transmitted in a globular pattern equally.

    >>
    >>Don't worry I know what an omnidirectional antenna is.
    >>
    >>>
    >>> The receiving antenna, however, is generally of a yagi type. What's a
    >>> yagi? Look on any roof top and you'll find one. The old standard
    >>> broadcast tv antenna is a yagi.
    >>>
    >>> The yagi aids in pinpointing the source. A more direct line equals a
    >>> stronger signal.

    >>
    >>I think you should go back to wireless networking school.
    >>When did you last see a laptop user carrying a Yagi around with it?
    >>The Yagi antenna is a Japanese invention but not relevant to this thread.
    >>
    >>

    >
    > Actually I have. I've seen a couple of truckers with yagi's mounted to
    > the mirror. Know of a few people that have them for in the home
    > because otherwise they'd have no signal at all.


    Ok and how is this relevant to what the OP asked??
    Do you suggest he gets a Yagi for all of his users?
    Or would 25 feet of wire and a few holes in the drywall be a more economic
    and reliable option?
    Helpful guy, Mar 15, 2009
    #7
  8. Jeff Wisnia

    PeeCee Guest

    "Jeff Wisnia" <> wrote in message
    news:gphbhp$ihn$...
    >
    > I'd like to learn why sometimes moving a wireless adaptor's antenna by
    > just a few inches can cause a significant performance difference.
    >
    > Ex: Today SWMBO came down to my office (We both work in our own business'
    > office.) complaining that internet access on the computer in her office
    > was slower than molasses in January.
    >
    > We use a Linksys WAP54G router to service the five computers in our
    > business. Her computer has a Linksys WUSB54G adaptor plugged into it.
    >
    > I gave her my usual reply that MY computer was connecting just fine and
    > that she has so much junk and obsolete files stuffed in her computer that
    > it probably needs an enema to get its performance back to where it used to
    > be.
    >
    > That strateguy didn't work, so I hauled my ass down to her office and had
    > a look.
    >
    > She was correct, internet access on her computer was awfully slow, even
    > though none of the other computers in the office were in use then.
    >
    > Her computer is the closest one to the router, only about 25 feet away
    > with nothing more than a couple of drywall partitions in the way. The
    > adaptor software reported excellent signal strength and I checked to make
    > sure that the wireless channel we were using was still unoccupied by any
    > of our neighbor's wireless systems.
    >
    > To make a long story shorter and less boring, I solved problem by simply
    > moving the wireless adaptor about four inches sideways on the bookshelf it
    > sat on, and her computer instantly regained its usual internet access
    > speed.
    >
    > I understand how multipath signals can cause RF nulling, but I'd expect
    > that the adaptor's software would report "poor signal strength" under
    > those conditions. It's the "good signal" report combined with lousy
    > performance that has my inquiring mind wondering what's really going on.
    >
    > Thanks guys,
    >
    > Jeff
    > --
    > Jeffry Wisnia
    > (W1BSV + Brass Rat '57 EE)
    > The speed of light is 1.8*10^12 furlongs per fortnight.




    Jeff

    What Philo says is right, multipath can cause distortion as well as nulling.
    Think of a TV picture with ghosting in it, the signals are strong but arrive
    at differnent times and distort the picture.
    In the case of WiFi the data bits are what get distorted so the routers
    spend all their time resending packets because the checksums don't add up.

    Mike's advice is also worth noting:
    Use wire if you can.
    Wireless works best when you can eyball antenna to antenna.

    It's also worth noting that WiFi is slow compared to Wired networking.
    Even the new 'N' standard is slow compard to the Gbit Wired NIC's most PC's
    come with today.

    Best
    Paul.
    PeeCee, Mar 15, 2009
    #8
  9. Jeff Wisnia

    Evan Platt Guest

    On Sat, 14 Mar 2009 22:43:09 -0400, richard <>
    wrote:

    >And you don't know jack. I held an FCC license for 5 years. I know
    >what I'm taliking about.


    A CB license? Wow.

    Must have been tough. I'm sure the toughest part was making out the
    check to the FCC.

    What license do you have now?
    --
    To reply via e-mail, remove The Obvious from my e-mail address.
    Evan Platt, Mar 15, 2009
    #9
  10. Jeff Wisnia

    Jeff Wisnia Guest

    PeeCee wrote:
    > "Jeff Wisnia" <> wrote in message
    > news:gphbhp$ihn$...
    >
    >>
    >> I'd like to learn why sometimes moving a wireless adaptor's antenna by
    >> just a few inches can cause a significant performance difference.
    >>
    >> Ex: Today SWMBO came down to my office (We both work in our own
    >> business' office.) complaining that internet access on the computer in
    >> her office was slower than molasses in January.
    >>
    >> We use a Linksys WAP54G router to service the five computers in our
    >> business. Her computer has a Linksys WUSB54G adaptor plugged into it.
    >>
    >> I gave her my usual reply that MY computer was connecting just fine
    >> and that she has so much junk and obsolete files stuffed in her
    >> computer that it probably needs an enema to get its performance back
    >> to where it used to be.
    >>
    >> That strateguy didn't work, so I hauled my ass down to her office and
    >> had a look.
    >>
    >> She was correct, internet access on her computer was awfully slow,
    >> even though none of the other computers in the office were in use then.
    >>
    >> Her computer is the closest one to the router, only about 25 feet away
    >> with nothing more than a couple of drywall partitions in the way. The
    >> adaptor software reported excellent signal strength and I checked to
    >> make sure that the wireless channel we were using was still unoccupied
    >> by any of our neighbor's wireless systems.
    >>
    >> To make a long story shorter and less boring, I solved problem by
    >> simply moving the wireless adaptor about four inches sideways on the
    >> bookshelf it sat on, and her computer instantly regained its usual
    >> internet access speed.
    >>
    >> I understand how multipath signals can cause RF nulling, but I'd
    >> expect that the adaptor's software would report "poor signal strength"
    >> under those conditions. It's the "good signal" report combined with
    >> lousy performance that has my inquiring mind wondering what's really
    >> going on.
    >>
    >> Thanks guys,
    >>
    >> Jeff
    >> --
    >> Jeffry Wisnia
    >> (W1BSV + Brass Rat '57 EE)
    >> The speed of light is 1.8*10^12 furlongs per fortnight.

    >
    >
    >
    >
    > Jeff
    >
    > What Philo says is right, multipath can cause distortion as well as
    > nulling.
    > Think of a TV picture with ghosting in it, the signals are strong but
    > arrive at differnent times and distort the picture.
    > In the case of WiFi the data bits are what get distorted so the routers
    > spend all their time resending packets because the checksums don't add up.


    That's the answer I was seeking, the TV ghosting analogy was appreciated.

    Thanks,

    Jeff
    --
    Jeffry Wisnia
    (W1BSV + Brass Rat '57 EE)
    The speed of light is 1.8*10^12 furlongs per fortnight.

    >
    > Mike's advice is also worth noting:
    > Use wire if you can.
    > Wireless works best when you can eyball antenna to antenna.
    >
    > It's also worth noting that WiFi is slow compared to Wired networking.
    > Even the new 'N' standard is slow compard to the Gbit Wired NIC's most
    > PC's come with today.
    >
    > Best
    > Paul.
    Jeff Wisnia, Mar 15, 2009
    #10
  11. Jeff Wisnia

    Evan Platt Guest

    On Sat, 14 Mar 2009 23:31:23 -0400, richard <>
    wrote:

    >With all that's been said so far, I'd just like to know, why are you
    >not using cable?
    >If you have so few users, a cable system would be better.


    Do you mean Ethernet?

    >I know of a guy who has a $5M house and he's wired his entire house.


    No you don't.

    >No wifi nowhere.


    Why not?

    >Splitters are only a few bucks each. You'd only need 2 or 3 at the
    >most to handle a few machines. Cutting and crimping cable together is
    >no big deal.


    Splitters??? What are you talking about?

    You really have no clue do you?
    --
    To reply via e-mail, remove The Obvious from my e-mail address.
    Evan Platt, Mar 15, 2009
    #11
  12. Jeff Wisnia

    Whiskers Guest

    On 2009-03-14, Jeff Wisnia <> wrote:

    [...]

    > To make a long story shorter and less boring, I solved problem by simply
    > moving the wireless adaptor about four inches sideways on the bookshelf
    > it sat on, and her computer instantly regained its usual internet access
    > speed.


    [...]

    'Something' was in the way of the direct path between the two aerials;
    could have been an ornament, or a water pipe, or a length of cable, or a
    steel joist, or a drawer full of cutlery. WiFi signals are easily
    reflected or blocked. You can turn a normal omni-directional WiFi aerial
    into a directional one with a bit of aluminium foil, and a baked-bean tin
    (with or without the beans) would be enough to create a 'blind spot'.

    That a small movement of one of the aerials improved performance, suggests
    that the obstruction was close to that aerial.

    --
    -- ^^^^^^^^^^
    -- Whiskers
    -- ~~~~~~~~~~
    Whiskers, Mar 15, 2009
    #12
  13. richard wrote:

    > http://www.freewebs.com/stevesebastianb/RX Splitter.jpg
    >
    > 2 and 3 position out are the most common.


    Those are for the coaxial cable. You can't plug a coax directly into a
    computer.

    > Let's say you have cable tv. How ya gonna get that signal from the
    > cable modem to all 10 of your tv's in the house?


    The coax feeds TVs, or more often, a digital TV box. The normal
    definition of a "cable modem" has nothing to do with TVs.

    One feed from that splitter can/may feed the actual cable modem, whence
    you would plug in your router (multiple PCs) and then via Ethernet cable
    to the computers. If you have multiple "cable modems" you need multiple
    IP addresses.

    I have a one-to-four splitter. One goes to a digital TV box for a LCD
    digital hi-def TV, one goes to an old analog TV, and one goes to my
    cable modem, where there is Ethernet to router, thence to three
    computers via Ethernet cables. The fourth is unused.

    > Do ya think the cable company runs a single wire from the station to
    > each and every house?


    Absurd question.

    > Dude, I've been doin electronics for forty years so yeah I do know
    > what I'm talking about.


    Not true, based on your post. You have no clue about cable internet...

    --
    -bts
    -Time Warner cable and RoadRunner subscriber
    Beauregard T. Shagnasty, Mar 15, 2009
    #13
  14. richard wrote:

    > <http://www.buzzillions.com/dz_105694_eagle_aspen_pro_brand_3_x_8_way_signal_reviews>


    That is for coaxial television signals. Not anything to do with
    computers.

    "Combine Off-air Or Cable Tv Signals With Satellite Signal To 1 Cable
    Expand System To Up To 8 Rooms"

    You keep proving you don't know anything about this matter.

    --
    -bts
    -Friends don't let friends drive Windows
    Beauregard T. Shagnasty, Mar 15, 2009
    #14
  15. Jeff Wisnia

    Evan Platt Guest

    On Sun, 15 Mar 2009 09:43:09 -0400, richard <>
    wrote:

    >http://www.freewebs.com/stevesebastianb/RX Splitter.jpg
    >
    >2 and 3 position out are the most common.


    Hmm. Funny, I can't get my etherenet cable to plug into that.

    >Let's say you have cable tv. How ya gonna get that signal from the
    >cable modem to all 10 of your tv's in the house?


    With a splitter.

    >Do ya think the cable company runs a single wire from the station to
    >each and every house?


    No.

    >Dude, I've been doin electronics for forty years so yeah I do know
    >what I'm talking about.


    No, you don't because you mentioned a splitter for HOME NETWORKING.

    You going to use RG58 for home networking, stoopid?
    --
    To reply via e-mail, remove The Obvious from my e-mail address.
    Evan Platt, Mar 15, 2009
    #15
  16. Jeff Wisnia

    Evan Platt Guest

    On Sun, 15 Mar 2009 09:53:14 -0400, richard <>
    wrote:

    >>Splitters??? What are you talking about?
    >>
    >>You really have no clue do you?

    >
    ><http://www.buzzillions.com/dz_105694_eagle_aspen_pro_brand_3_x_8_way_signal_reviews>


    Please warn me before you post if I'm drinking any liquids...
    --
    To reply via e-mail, remove The Obvious from my e-mail address.
    Evan Platt, Mar 15, 2009
    #16
  17. Beauregard T. Shagnasty, Mar 15, 2009
    #17
  18. Jeff Wisnia

    G. Morgan Guest

    Beauregard T. Shagnasty wrote:

    >I have a one-to-four splitter. One goes to a digital TV box for a LCD
    >digital hi-def TV, one goes to an old analog TV, and one goes to my
    >cable modem, where there is Ethernet to router, thence to three
    >computers via Ethernet cables. The fourth is unused.


    That is not the optimal setup. You should have the main drop split with a
    2-way, one to the modem and one to another 2-way splitter with both TV's
    connected to it.

    If you need an explanation why, I can provide one if necessary.

    --
    "Newspaper claims car thief transformed into a goat"
    http://news.yahoo.com/s/ap/20090124/ap_on_fe_st/odd_goat_thief_5

    **Important Update**
    Magic goat detained for armed robbery:
    http://news.uk.msn.com/odd-news/Article.aspx?cp-documentid=13298291
    G. Morgan, Mar 15, 2009
    #18
  19. Jeff Wisnia

    G. Morgan Guest

    G. Morgan, Mar 15, 2009
    #19
  20. Jeff Wisnia

    G. Morgan Guest

    G. Morgan, Mar 15, 2009
    #20
    1. Advertising

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