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WiFi Antenna Coupling

  1. Nov 1, 2009 #1
    Hi - I live full time in an RV that is surrounded by aluminum - essentially a faraday cage, except for a few rather small windows. I'd like to mount a WiFi antenna on the roof and run a cable in a window or thru a small hole.

    Basic issue - how to get a good signal from a campground WiFi inside my "faraday cage" RV without adding active amplifiers, etc.

    My laptops have built in antennas in the display lids, so I'd like to somehow couple the outside signal into my laptops inside (without a DIRECT connection to the WiFi card inside the laptops). I want, instead, to RE-RADIATE the signal from the cable to the laptops. 802.11b and 802.11g WiFi networking equipment operates at a range of frequencies from 2.412 GHz to 2.462 GHz.

    Can I simply terminate the inside cable with a short piece of wire to re-radiate the signal (now inside instead of outside my cage)? How long should the piece of wire be (assuming a 14 guage copper wire)? Should I ground the cable shield to the RV frame on one end or both? Will this work at all? Maybe I could put the cable radiator OUTSIDE the small window where my laptops are?

    Any better ideas?

  2. jcsd
  3. Nov 1, 2009 #2


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    You can get USB adapters that let you communicate with a wireless router from a computer's USB port. They look like a large thumb drive and may come with a small stand to sit on a shelf.

    If you put an extension cable on one of these and plugged it into your laptop it would enable you to receive wireless signals from the central antenna at a campground.

    They look fairly waterproof, but you could put a plastic cover over it to keep the sun and rain off it.

    The current best standard is the 802.11N and it would be worth getting that type as it gives better range and is compatible with earlier types.

    Setting it up is quite tricky and you might be able to get the computer store to set your laptop up for you, especially as it would mean disabling the internal Wireless connection.

    EDIT: You would need to have USB 2 on your laptop, otherwise it would be too slow for using as a wireless connection.
    Last edited: Nov 1, 2009
  4. Nov 1, 2009 #3
    Thanks for the idea vk6kro. I'm already familiar with those USB adapters, but my wife and I typically run both laptops at the same time. I'd rather not have to buy two of those adapter$. Since I already have an external WiFi antenna (about 10" long), I'd much rather try the coupled antenna idea if it has a chance of working.
  5. Nov 1, 2009 #4


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    I guess anything is worth a try, but I expect you will need an amplifier for the antenna.
    Don't forget your laptops are transmitting as well as receiving.

    So, you might get away with it at one campground but what about the next one where you are parked at the far end of the lot?

    The USB adaptors are not expensive ($50 for the N types and about half that for the other, slower ones) and they give you the chance to upgrade your speed and range to the N types.

    Why don't you drive to a computer store, find an expert and have a chat about it? Specialist computer stores usually have well trained staff.
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