Have I gone a bit loopy with this huge antenna?

Discussion in 'Modding Forum' started by lawsie, Nov 5, 2006.

  1. lawsie

    lawsie LI Guru Member


    I want to give my sister free net access so am attemping to extend the range of my network. I have a WRT54G V5 with frame burst on. A friend who lives two doors away can access my wireless network through at least four walls with no problem at all.

    Perhaps a little naievly I looked on ebay and plumped for the antenna with the highest DB I could find, I bought this model -

    Tech spec -
    Size - 500/75mm
    Weight - 0.4 kg
    Gein level - 17 dBi
    Polarisation: vertical/horizontal
    Angle: vertical: 32, horizontal:28
    Impedanc: 50 Ohm

    I have fixed the antenna to the back of the router and dangled the antenna over a hanging basket frame outside my study at the rear of the house where the router is. That's pretty much all I've done so far. From the rear (left hand side on diagram) part of the house we can get a weak signal if we hold the laptop up to the window, but only just.

    I've got a horrid feeling I've gone about all this the wrong way. Help!
  2. arigosh

    arigosh Network Guru Member

    I think at least part of the problem is that on your sister's side you're not using a high gain directional antenna like the one you use on your side.
  3. lawsie

    lawsie LI Guru Member

    my sister has a pcmcia card (a linksys one of course). So am I right in thinking that you can't just chuck out a massive signal from the router and hope that a normal reciever will be able to pick it up?
  4. DallasFlier

    DallasFlier Network Guru Member

    Yes, you're right, you need the high-gain, directional antenna at both ends, which means you need to set up another WRT with similar antenna at her place, then you can link the two together using WDS, and her notebook card can then easily access via the local router.
  5. crawdaddy

    crawdaddy Network Guru Member

    This is not neccisarily true. I am shooting a .2 mile link down the street and I can pick up the signal and surf the net using a simple internal wireless network card. It's all in the aiming....very careful aiming....
  6. lawsie

    lawsie LI Guru Member

    I was hoping that was the case (internal card), at the moment I have the antenna just sort of hanging there, I'll play about with it and move it around.
  7. arigosh

    arigosh Network Guru Member

    Just remember that a Yagi antenna is a directional antenna. You need to point the end of the cylinder towards your sister's place. Just as if you wanted to look at her place through the cylinder.
  8. lawsie

    lawsie LI Guru Member

    oh I didn't know that!!! I'll aim it later and let you know the results. The moment it's firing it's signal at the top of my shed!
  9. teststrips

    teststrips LI Guru Member

    I was gonna say, a highly directional antenna like that should be able to give you a line of sight connection at a .5 mile or more (a lot further if you have an antenna on both ends 5-10 miles)

    I do think you're going about it the wrong way though, you should leave your router alone + hook the antenna up to her comptuer + point it at your house.

    If you put the antenna on your router, you will drasticallly reduce the wireless signal in your home.

    If you choose to leave the antenna on the router end, make sure you have your antenna settings in the firmware correct. Many times by default one antenna is set to recieve + the other to send... this would be worthless! One of the antennas will be turned OFF + the antenna you bought should be both send/recieve.

    Antennas don't magically make more signal output - they only focus it. 2 types of antennas:
    1 - omni (not what you bought)- they send signals in every direction - the higher the gain, the more the signal pattern looks like a donut - super high gain would cause a flattened donut. (omni antennas focus upwards and downward signals outward = better coverage around the antenna = worse coverage up/down from the antenna.
    2 - directional - they focus all the signal in one general direction. The higher the gain the less the beam widens over distance. These antennas aren't what most people want for their home, but it IS what you want to get a signal to your sister's house.
  10. lawsie

    lawsie LI Guru Member

    ooooh, all fantastic advice, I've just popped outside and aimed it at my sisters house!
  11. tuskan

    tuskan Network Guru Member

    1. Yagi is ****
    2. Never beleive that yagi can be more than 15 db.
    3. if they say 15 db - then it is something like 10 in real
    4. even good yagi collecting all the noice around
  12. teststrips

    teststrips LI Guru Member

    Did your friend (who lives 2 doors away - refrenced in post #1) loose connection to your house? Are you still able to connect from within your house?
  13. lawsie

    lawsie LI Guru Member

    yes to both questions, I'm wondering if this antenna is doing anything at all!
  14. lawsie

    lawsie LI Guru Member

    On chatting again to my friend who lives two doors away it turns out he pretty much entirely lost all signal as soon as I had attached this antenna.

    I've now removed the antenna, I'm going to start again. I've been looking through the Linksys range to see if they do anything like a signal booster?

    Any ideas?
  15. HennieM

    HennieM Network Guru Member

    Lawsie, here a few things to try:

    1) You should connect the Yagi to the left (as seen from the front of the WRT) antenna connector, try a few orientations, and then do the same when the Yagi is connected to the right antenna connector. I found the left one to be better for external antennas, but try both.

    2) Aim the Yagi to "sister's house" while holding it as if connected to an upright mast or pole. Note the signal strength. Then, rotate the Yagi through 90 degrees - as if connected to a horizontal mast, and note the signal strength again. Antennas have polarization, so you need to match the Yagi's polarization with whatever is on the other side. I found this can make a 20dB difference (although with the little built-in PCMCIA card antennas there's usually less difference).

    3) Move the "sister's device" (I forget, is it a laptop?) around a bit (up, down, left right, forward, backwards, rotated [so pc-card faces the WRT], etc.), and note signal strength. If the signal from the WRT has to traverse a wall at an angle, that wall becomes very thick (as seen by the signal), so try to have the signals go through walls at near 90 degrees.

    4) You menioned your WRT is a V5. You can load dd-wrt micro, which is custom firmware, which will allow you to adjust the Transmit (Tx) strength. However, this will only boost the signal Tx'd from the WRT - "sister's device" must still get her signal to the WRT.

    5) If "sister's card" is a WPC54G/S, that might be the trouble. I found the WPC54 cards to get only half as far as other cards, so maybe try (borrow and test before you buy) another card.

    6) To regain the connection to "friend who lives 2 doors away", try to re-orient your WRT so the other antenna (the stock one still on the WRT) "looks" through as few obstacles as possible to your friend. When you connect the Yagi, you are directing all the signal from the Yagi in one direction, as opposed the 360 deg. signal that the stock antenna Tx'd.
  16. lawsie

    lawsie LI Guru Member

    this is all fantastic, although I must admit I've been a little impatient and have already sold on this antenna!

    I REALLY appreciate your help though
  17. HennieM

    HennieM Network Guru Member

    No probs
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