1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

WiFi Signal Strength and Computer Orientation

  1. Nov 2, 2014 #1
    Hello everybody :)

    This is my first post! I have a mystery about radio communication that I was wondering about for a long time:

    If I have understood correctly, most computers have a single WiFi antenna in the shape of a rod, which is placed in a particular orientation. My question is this: why does the WiFi signal strength seem to be unaffected by the orientation of the antenna even though the voltage induced will depend on the direction and polarisation of the WiFi radio waves? For example, my laptop (as far as I know) has a single antenna in the plane of the keyboard, and if I rotate my computer through many angles, my signal strength is unaltered.

    Could it be that there are multiple (maybe 3) radio receivers that are positioned perpendicular to each other for optimum radio wave capture? Or maybe the router has 3 perpendicular transmitters?

    Thanks a lot for your help!
    Nat :)
  2. jcsd
  3. Nov 2, 2014 #2


    User Avatar
    2017 Award

    Staff: Mentor

    Signal strength does depend on the orientation, but the difference is small compared to other issues like walls.
  4. Jun 1, 2015 #3
    Thanks for the reply :)
  5. Jun 1, 2015 #4


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    there is a huge difference in signal strength dependent on antenna orientation, the difference between horizontal and vertical polarisation is around 25 - 30 dB

    Over the short distances that WiFi is used, several 10's of metres, it is as mfb said, not too much of an issue due to all the reflections of other objects
    Over longer distances kilometres ++ it makes a major difference and matched antenna orientation is a must


    PS ... nice to see you return after many months with a response :smile:
    so many never bother to ever come back with a thanks
    hope to see more of you on the Physics Forums :smile:
  6. Jun 2, 2015 #5


    User Avatar
    Gold Member

    That may be true for some sort of dipole, but I believe there are other more complicated antenna designs available that can get closer to an ideal isotropic radiator, something I would guess computer manufacturers may take advantage of.
  7. Jun 3, 2015 #6


    User Avatar
    Science Advisor

    One of the features of IEEE 802.11n is the optional use of multiple antennas in order to get a better signal strength.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook