wireless antenna
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Thread: wireless antenna

  1. #1
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    Arrow wireless antenna

    i looked for another place to put this but as it isn't really a security q i couldn't find anywhere else. once i ge this solved i'll have lots of wireless security q's to ask so if you have advice on that too it would be great =)

    i want to set up a wireless network which will go to about 400m in range using wireless network cards and custom made antenna's or "cantenna's". i've already done some research on the matter and i'm almost ready to get started but wanted some addition information....

    my problem lies with the connection from my cantenna (pringles type) and then wireless card (laptop PCMCIA). i know i would use a pigtail for that connection but i might need a longer cable.

    the cantenna would be on the roof (maybe 1m from roof tiles) and the pc which holds the PCMCIA card would be in the roof. this would mean i would need ~3m of cable and i am worried about losing signal strength. what are my options?

  2. #2
    Trumpet-Eared Gentoo Freak
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    I don't think you'd loose your signal over 3 metres, What cable do you use ?
    Coaxial, UTP or STP ?

    Do you know the ouput signal ?

    Greetz,
    Come and check out our wargame-site @ http://www.rootcontest.org
    We chat @ irc.smdc-network.org #lobby

  3. #3
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    Three meters should be fine for just about any kind of wire. If you are really concerned about signal strength though, put an amplifier on the line. Caveat: amplifing the signal screws up your signal to noise ratio (SNR) so if you don't need it for the extra umph, don't use it. Also.....there are better things than pringles cans to build a yagi antenna out of. Though the cans are cool. I built one for a "proof of concept" project in a security class I took. It blew everyones mind.

  4. #4
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    .: Shrekkie :. >>> still unsure of details, what cable SHOULD i use, i'm thinking lmr400.

    thread_killer >>> i've heard these pringles can's can do xcess of 400m, is this true in practice as i need at LEAST 400m with fairly good line of sight.


    pigtails that i've seen are short in length so i'lm looking at "lmr 400" . i haven't made the antenna yet so if there is better then pringles i would appreciate other idea's.

    if anyone knows about lmr400 (or another cable i should use) do i still need a pig tail or is the lmr400 the only cable needed?

  5. #5
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    Two good quick links. I'll post more later. My son just woke up.

    http://www.nemr.net/~aschmitz/antennas/calcantenna.html

    http://www.andrewhakman.dhs.org/yagi/

  6. #6
    Gray Haired Old Fart aeallison's Avatar
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    LMR 400 will work just fine for up to 100 feet or so (US measurements ) LMR 600 is what I used to run up a 180 foot tower to several dish antennae and a single omni directional for wireles laptop users, the dishes were for "bridges between our wired networks. I had sucessful connections over 30 miles... I still have one of the omni directional ant. and an amplifier for a cisco airnet 340b...I will let you have them cheap, I have over 3500 bucks in them but would take conciderably less
    I have a question; are you the bug, or the windshield?

  7. #7
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    does conciderably less mean like 1000. and i'm assumin ur talking AUD =)

    thanc 4 da linx thread_killer ... they look great ... reading now.

  8. #8
    Gray Haired Old Fart aeallison's Avatar
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    Talking

    Or less...The antennae is a fiberglass omni directional at 12db gain, originally cost around $500.00 US (I don't convert euros well) The Amplifier was around $600.00 or so (it was modified for peak output with the particular aironet bridge radio) The radio was around $1500 dollars. I have roughly 50 to 60 feet of lmr400 with the type "N" connectors on each end and the pigtail from the radio to the amp, and the pigtail from the amp to the antenna. This used to be my internet gateway to an ISP I helped design that folded due to poor management It's not doing me any good now...nor will it ever again.

    You pay the shipping and can have everything for $800.00
    I have a question; are you the bug, or the windshield?

  9. #9
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    ahh aeallison if only i had the cash =)

    i wanted a wireless network (point-point). cost was 250+ [AU$] then i got it down to <150 [AU$] ... i think i CAN get it all done round the 150mark depending on how everything goes.

    basically, i don't have the money to buy all these cool things that i so badly want. i want a latop too but this is cheaper and more fun so the lapi will hafta wait =)

    thanx for the offer tho.

  10. #10
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    You seem to have gotten some replys, but I'd be happy to help out with anything that I can. I have a back ground in both electronic engineering as well as RF communication, so building yagi's is right up my alley. There are lots of ways to fabricate on the cheap. Simple things like a "C" cell battery provides exactly 50ohms resistance can make things expedient when fabricating. Although I haven't done it yet, I would imagine a google search on something like "field expedient antenna" would turn up some interesting unclassified military field manuals. I've seen commo guys make antennas in the field out of all sorts of wierd crap like speaker wire and peach cans, so it can be done. It's just a matter of finding subtitute items with similar properties to the expensive crap that the vendors are hawking.

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