Rain effects

topic posted Tue, September 21, 2004 - 6:33 AM by  Unsubscribed
Does rain affect wi-fi signal? It seems like the reception goes south on my wireless bridge every time it rains heavily.
posted by:
  • Re: Rain effects

    Tue, September 21, 2004 - 11:56 AM
    Noise in general effects signal strength.
    Rain creates noise.
    'silent noise' such as other wireless products, have an effect too.
    • Unsu...

      Re: Rain effects

      Wed, September 22, 2004 - 2:05 AM
      Wow. Really? How does noise effect radio waves? Are the wavelengths that close together?

      What a trip...
      • Re: Rain effects

        Sat, September 25, 2004 - 12:05 PM
        rain doesn't create RF noise, but water on outside wiring and lighting can definitely affect the wired connection. that's most likely what you notice during a storm. a rain storm outside should have zero effect on the wi-fi signal inside your home, and little to zero effect at all outside, considering 802.11 ranges.
        • yay
          offline 0

          Re: Rain effects

          Sun, September 26, 2004 - 11:10 AM
          the frequency that 802.11 works at is abosorbed by water. which is one of the reasons that you don't need a license to use it.
          • Re: Rain effects

            Mon, September 27, 2004 - 12:58 PM
            Say what?

            No disrespect, but I'm not buying your radio frequency 'absorbed by water'. In particular, the idea that rain outside my house is f___ing with any kind of RF inside my house.

            I'm not saying flat out that you're wrong, just that it doesn't really jive with my (admittedly limited) knowledge and experience. Can you point me in the direction of some sources for these claims?

            • Ed
              offline 4

              Re: Rain effects

              Mon, September 27, 2004 - 2:21 PM
              actually the peak absorption rate for water is around 20Ghz, so considering that 802.11 is running at 2.4 Ghz the rain will not "absorb" your signal. In fact the wavelength of a 2.4 signal is approx 4.8 inches long, so rain won't even block the signal.
              It is a myth that microwave ovens heat by items absorbing the RF. In fact the RF waves cause the molecules to "twist" creating heat. I am sorry that is not a real scientific explaination. But if you are losing your signal in the rain I would check all of your connections to make sure water is not getting in them. Also check your antenna. maybe it is windy at the same time it rains. An antenna that moves can cause signal problems.
              • Re: Rain effects

                Mon, September 27, 2004 - 5:01 PM
                Physical Mass blocks reception.
                Can't we all agree on this?
                If I have a line-of-sight, I'll get better reception than being between a series of solid walls.

                Now consider that Rain actually has Mass.
                A lot of rain coming down creates a lot of signal blockage.
                This has nothing to do with frequency.
                AM&FM radio get worse the same way - not as good reception in rain, and with too many walls in the way.

                I mooch free WiFi from the cafe across the st. from my house.
                The WiFi hub is located Inside the cafe.
                It's obviously completely dry.
                I have a laptop with an internal WiFi card.
                My reception sucks when it rains, and also during high traffic times (a very busy street between the cafe & I).
                I get great reception on the average clear night after traffic has died down.
                If I want reception durring rush hour, I have to go sit on my porch.

                I don't make out to be any kind of expert either,
                this is just what I've come to figure out through trial & error.
                • Re: Rain effects

                  Tue, September 28, 2004 - 2:04 PM
                  No argument there. Rain will affect your WiFi reception from accross the street. So will a brick wall. So will anything with some mass.

                  My problem was with the assertion that rain outside my house could somehow f___ up RF signals contained entirely inside my house by 'absorbing' the frequency. I'm gonna need a bit more explaination and evidence before I can buy into that one.

                • Re: Rain effects

                  Wed, September 29, 2004 - 8:20 AM
                  I will agree physical mass blocks (or reduces) reception, but comparing rain to solid walls in not an accurate comparison.

                  It is true that anything within the fresnel zone of a signal will cause attenuation and possible total loss of signal.

                  And a street with busy traffic between you and signal can cause poor signal (vehicles are metal, wi-fi does not like metal). There are many things that can effect a wi-fi signal.

                  But I have installed many AP's inside and outside and can say that I have never seen rain fade or total loss on a properly installed system.

                  That being said, the only real true way to see is to set up a spectrum analyzer and measure signal strength before, during and after a torrential rain. I would concede that there would probably be a drop in signal strength during downpour but it should be minor and you may not even notice it

                  What I HAVE seen is during a rainstorm is water running down a vertical surface (i.e. wall, window) causing signal loss. Water is an excellent reflector. If you are outside a building and getting your signal through a window or a wall and water is running down surface you could have problems.

                  Just remember that the higher the frequency, the shorter the range, and the signal is more prone to interference.
        • Unsu...
          Yeah, I'm referring to an access point that is in the neighboring apartment, separated by one shared wall. There isn't any rain or distance between us, but WOW does rainy weather seem to debilitate my signal reception.

          Still, it's probably more complex than any of that. My neighbor (my brother-in-law) is using a Corega wireless router, and my wireless-to-ethernet bridge (802.11g) is also Corega. For some reason the bridge has trouble staying on his network, but my iBook with AirPort card (802.11b) is always, flawlessly connected to his LAN.

          I'm about to give up on his LAN and get my own broadband, and admin it through an Apple AirPort Express. I expect blissfully uninterrupted service soon...
  • Unsu...

    Re: Rain effects

    Thu, December 16, 2004 - 3:21 PM
    A friend of mine is a network engineer, and has been working with wireless lately. I've been out of touch with him, but he recently visited, and like the guy who hits up his doctor-guest for free advice ("I've got this funny pain, right here..." *points), I asked him about this problem.

    He said that because a concrete wall divides my apartment from my bro-in-law's neighboring apartment, the signal is likely being bounced around from outside rather than going through the thick concrete wall.

    When walls get wet, the -- crap, I've forgotten the term -- either reflectivity or absorptive nature of them changes, making reflected signals harder to interpret.

    He also told me that if either we or the neighbor uses a microwave with a bulb operating at a similar range, everything goes bye-bye.

    Which so far has fit the pattern exactly.
    • Unsu...

      Re: Rain effects

      Thu, December 16, 2004 - 8:34 PM
      floyd and your engineer friend have it correct. the deflection issue is probably your biggest issue. The "mass" of water during a storm is no where near sufficient enough to reduce the radio wave signal enough to notice unless you are already stretching the signal. Concrete walls are a huge problem due to density issues. Less signal can actually penetrate the wall so what you get is "bounced" signals. I actually pick up more signals during rainstorms. I think, in part, because of how I'm situated in a high rise bldg.

      Depending on where your computer sits, you might try moving it closer to the window or invest in a booster antenna which you can leave near the window and point towards your computer.

      • Unsu...

        Re: Depending on where your computer sits...

        Wed, January 12, 2005 - 10:00 PM
        Actually, I'm going to get a little more pro-active, since his wifi router appears to be half crap, and am going to get broadband for our own apartment, circumventing the concrete wall situation entirely.

        Thanks for the clarification!

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