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Thread: Wifi Directional question?

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  1. #11

    Default

    Google up "cantenna" - lots of stuff out there. Some of it more snake oil than real - but it's out there.

  2. #12
    Join Date
    Oct 2008
    Location
    Louisiana Gulf Coast
    Posts
    1,021

    Default

    Yes and no.

    Pringles can, no... it is cardboard with a metallic looking inside coating.

    But other cans are suitable. Ideally, for 2.4 ghz, a can with 3.25" diameter is needed. The longer the better, but one can length will suffice.

    You can buy the Super Cantenna. www.wirelessgarden.com

    This works well, and if you don't feel like spending a lot of time on the project, as good as any.

    I made a good cantenna with two Heinz baked beans cans soldered end to end, and an N socket with a 1.21 long piece of brass tubing soldered on the inside. That's a 1/4 wave of 2.4 ghz.

    Aside, a cantenna, or more accurately, a Waveguide, has appx 12 db gain and about 30 degree conical pattern.

    There is a specific distance the antenna element should be from the back end of the can depending on frequency and diameter of the can. There are online calculators for this.

    http://www.turnpoint.net/wireless/cantennahowto.html

    http://www.turnpoint.net/wireless/has.html

    http://www.turnpoint.net/wireless/antennas/hunts.html Optimum size can same diameter as I used.

    http://www.turnpoint.net/wireless/an.../bigchunk.html

    BTW, I attached the N socket to the can with pop-rivets.












    Due to high loss in the coax, I use a very short "pigtail" and an external USB wifi adapter. Then I use a long USB Male-A to Female-A cable from my laptop to the wifi adapter.

    I mount the can to an old camera tripod.

    It works.

    -----

    Going further, you can mount the cantenna in place of the feedhorn on a DTV or Primestar dish.


    Cantenna Calculator
    How to build a tin can waveguide antenna
    Hunt's Pasta Sauce Can Antenna
    Lincomatic's Homebrew WiFi Antennae
    Modified Coffee Can Antenna
    Nalley Big Chunk Antenna
    USB Cantenna
    WiFi Antennas-Super Cantenna Wireless Booster Antenna
    YouTube - AmateurLogic.TV Episode 3
    YouTube - CANTEL
    YouTube - directional wifi antenna construction
    YouTube - How Can Wireless Internet Connectivity Be Of Use...
    YouTube - This is my usb Cantenna
    YouTube - Wifi Cantenna DIY - can on router
    YouTube - Wireless Cantenna
    Last edited by AE5JU; 08-28-2009 at 07:13 PM.

  3. #13
    Join Date
    Oct 2007
    Location
    MELBOURNE VIC
    Posts
    173

    Default

    Gday all

    Here are the photos of the Directional Copper plated 5/8 wave 2.4GHZ antenna that i have made

    Im about to test it looking for new wireless networks in my area

    Sorry about the pictures they were taken on my phone :P

    Im about to build some others very soon, Thank you everyone for posting your ideas and models
    Attached Images Attached Images
    Last edited by VK3FTIM; 08-29-2009 at 03:29 AM.
    [CENTER]73's and Good DX VK3FTIM
    [COLOR="Lime"]Victor - Kilo - [/COLOR][COLOR="Red"]THREE - [/COLOR][COLOR="Lime"]Foxtrot - Tango - India - Mike[/COLOR]
    Proud [COLOR="Red"]ICOM[/COLOR] User (IC-718)
    __________________________________________
    [COLOR="Lime"]Amateur Frequency's I can be found on.[/COLOR]
    3530 CW 3620 LSB 7025 CW 7080 LSB 7102 LSB 21225 USB 28030 CW 28350 USB (all in KHZ)
    ___________________________________________
    [COLOR="Red"]Non Amateur radio Frequency's i can be found on[/COLOR]
    10.818 SCOUT 5301 (OUTPOST VKS737 4WD CLUB)
    27.155 Chan 16 LSB ( VBO-593 "Viking")
    ___________________________________________

    Member of The Young Hams Net ( 7.130 LSB +/- 5khz )
    [url]http://groups.yahoo.com/group/young_hams_net/[/url][/CENTER]

    [HTML]<Center><a href="http://www.nerdclub.net/alp"><img src="http://www
    .nerdclub.net/alp/banners/banner_460x60_alp.gif" borde
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  4. #14
    Join Date
    Oct 2007
    Location
    MELBOURNE VIC
    Posts
    173

    Default

    Quote Originally Posted by AE5JU View Post
    Yes and no.

    Pringles can, no... it is cardboard with a metallic looking inside coating.

    But other cans are suitable. Ideally, for 2.4 ghz, a can with 3.25" diameter is needed. The longer the better, but one can length will suffice.

    You can buy the Super Cantenna. www.wirelessgarden.com

    This works well, and if you don't feel like spending a lot of time on the project, as good as any.

    I made a good cantenna with two Heinz baked beans cans soldered end to end, and an N socket with a 1.21 long piece of brass tubing soldered on the inside. That's a 1/4 wave of 2.4 ghz.

    Aside, a cantenna, or more accurately, a Waveguide, has appx 12 db gain and about 30 degree conical pattern.

    There is a specific distance the antenna element should be from the back end of the can depending on frequency and diameter of the can. There are online calculators for this.

    http://www.turnpoint.net/wireless/cantennahowto.html

    http://www.turnpoint.net/wireless/has.html

    http://www.turnpoint.net/wireless/antennas/hunts.html Optimum size can same diameter as I used.

    http://www.turnpoint.net/wireless/an.../bigchunk.html

    BTW, I attached the N socket to the can with pop-rivets.

    Due to high loss in the coax, I use a very short "pigtail" and an external USB wifi adapter. Then I use a long USB Male-A to Female-A cable from my laptop to the wifi adapter.

    I mount the can to an old camera tripod.

    It works.

    -----

    Going further, you can mount the cantenna in place of the feedhorn on a DTV or Primestar dish.


    Cantenna Calculator
    How to build a tin can waveguide antenna
    Hunt's Pasta Sauce Can Antenna
    Lincomatic's Homebrew WiFi Antennae
    Modified Coffee Can Antenna
    Nalley Big Chunk Antenna
    USB Cantenna
    WiFi Antennas-Super Cantenna Wireless Booster Antenna
    YouTube - AmateurLogic.TV Episode 3
    YouTube - CANTEL
    YouTube - directional wifi antenna construction
    YouTube - How Can Wireless Internet Connectivity Be Of Use...
    YouTube - This is my usb Cantenna
    YouTube - Wifi Cantenna DIY - can on router
    YouTube - Wireless Cantenna

    Thank you very much for all your links and calculators

    Everyone has been so helpful i will begin building these now and show all results and photo's

    QRZ Forums has such a great bunch of people on it
    [CENTER]73's and Good DX VK3FTIM
    [COLOR="Lime"]Victor - Kilo - [/COLOR][COLOR="Red"]THREE - [/COLOR][COLOR="Lime"]Foxtrot - Tango - India - Mike[/COLOR]
    Proud [COLOR="Red"]ICOM[/COLOR] User (IC-718)
    __________________________________________
    [COLOR="Lime"]Amateur Frequency's I can be found on.[/COLOR]
    3530 CW 3620 LSB 7025 CW 7080 LSB 7102 LSB 21225 USB 28030 CW 28350 USB (all in KHZ)
    ___________________________________________
    [COLOR="Red"]Non Amateur radio Frequency's i can be found on[/COLOR]
    10.818 SCOUT 5301 (OUTPOST VKS737 4WD CLUB)
    27.155 Chan 16 LSB ( VBO-593 "Viking")
    ___________________________________________

    Member of The Young Hams Net ( 7.130 LSB +/- 5khz )
    [url]http://groups.yahoo.com/group/young_hams_net/[/url][/CENTER]

    [HTML]<Center><a href="http://www.nerdclub.net/alp"><img src="http://www
    .nerdclub.net/alp/banners/banner_460x60_alp.gif" borde
    r="1" width="460" height="60"></a> </center>[/HTML]

  5. #15
    Join Date
    Oct 2004
    Location
    Jacuzzi
    Posts
    12,964

    Default

    Well here's my quick and dirty experiment I made in about 10 minutes after reading this thread using an old RCA Direct TV satellite dish, a Belkin wifi dongle and a camera tripod I had in the shack.

    Nice thing about wifi dongles and USB cable... No coaxial feedline and zero RF losses.

    In side by side tests the Wifi Dongle without the dish exhibited a 2.0 and sometimes a 5.0Mbps signal. However, with the dish pointed at the same signal source it increased to 36 Mbps.

    So yes, it does appear to work and rather well...

    Oh, yes before I forget here's some pics of the contraption I made up for the test...



    I removed the LNB and secured the dish to the camera tripod using wire ties. It appears the best signal is achieved with the dish oriented slightly forward at approx. 45 degrees in this position. The camera tripod was useful in making these adjustments very easily.



    Closeup of Belkin 802.11 USB wifi dongle. It's held in place with sticky putty.



    In fact this message is being posted on QRZ using this antenna at the moment. Seems to be a keeper.

    My Best.
    Last edited by KC8VWM; 08-29-2009 at 04:53 AM.
    73 de Charles - KC8VWM
    North American QRP CW Club #3159, SKCC# 5752

  6. #16
    Join Date
    May 2009
    Location
    CM97cg
    Posts
    753

    Default

    Quote Originally Posted by KA7O View Post
    Google up "cantenna" - lots of stuff out there. Some of it more snake oil than real - but it's out there.
    Yup, the good old cantenna.

    The pringles can is a myth. Doesnt work well. However a campbells soup can is a different story. Solid metal, works "decent" better then a omni antenna, but no where near as good as an actual 2.4ghz yagi.

    I've personally used a USB dongle and a BBQ gril lid as a reflector. Showed a 9dB gain with the reflector.
    Last edited by KI6ZIF; 08-29-2009 at 04:10 AM.
    "[I]Keep the Amateur in Amateur Radio. Keep the professionals and Part 90 out[/I]." Ed Brooks, W5HTW (SK)

    [B][SIZE=3]If you can't make fun of yourself, go sit in the truck :cool: - W5WPL[/SIZE][/B]

  7. #17
    Join Date
    Oct 2007
    Location
    MELBOURNE VIC
    Posts
    173

    Default

    Here is the new Cantenna of which i built and just tested and it beats the arse out of my other directional antenna

    It found 6 Networks while the other one found just 3

    The cantenna measured 10 DBi while the other directional only measures 3 DBi

    It was made out of a "Milo tin" 105mm long 70mm across

    The hot element is 3 cm's Long

    The connecter is 2cm's (1/4wave) length away from the back
    Attached Images Attached Images
    Last edited by VK3FTIM; 08-29-2009 at 04:59 AM. Reason: Inserting Measurements
    [CENTER]73's and Good DX VK3FTIM
    [COLOR="Lime"]Victor - Kilo - [/COLOR][COLOR="Red"]THREE - [/COLOR][COLOR="Lime"]Foxtrot - Tango - India - Mike[/COLOR]
    Proud [COLOR="Red"]ICOM[/COLOR] User (IC-718)
    __________________________________________
    [COLOR="Lime"]Amateur Frequency's I can be found on.[/COLOR]
    3530 CW 3620 LSB 7025 CW 7080 LSB 7102 LSB 21225 USB 28030 CW 28350 USB (all in KHZ)
    ___________________________________________
    [COLOR="Red"]Non Amateur radio Frequency's i can be found on[/COLOR]
    10.818 SCOUT 5301 (OUTPOST VKS737 4WD CLUB)
    27.155 Chan 16 LSB ( VBO-593 "Viking")
    ___________________________________________

    Member of The Young Hams Net ( 7.130 LSB +/- 5khz )
    [url]http://groups.yahoo.com/group/young_hams_net/[/url][/CENTER]

    [HTML]<Center><a href="http://www.nerdclub.net/alp"><img src="http://www
    .nerdclub.net/alp/banners/banner_460x60_alp.gif" borde
    r="1" width="460" height="60"></a> </center>[/HTML]

  8. #18
    Join Date
    Mar 2006
    Location
    Newcastle, NSW, Australia
    Posts
    2,876

    Default

    Good fun!!!

    There are lots of ingenious 2.4GHz antennas; the "Wi-Fri" makes me smile;

    http://www.usbwifi.orconhosting.net.nz/wokaxim.jpg

    From here;

    http://www.usbwifi.orconhosting.net.nz/

    Keep experimenting; it's cheap fun and priceless knowledge.

  9. #19
    Join Date
    Oct 2008
    Location
    Louisiana Gulf Coast
    Posts
    1,021

    Default

    Here's another, a biquad.

    http://www.youtube.com/watch?v=Gm1z6yJyQ2s

    KC8VWM wrote:

    It appears the best signal is achieved with the dish oriented slightly forward at approx. 45 degrees in this position.

    Yes, and that is the design of this type of dish. It is contoured so that the "feedhorn" is not blocking any of the incoming or outgoing signal.

    Focal point calculation of a dish:

    http://www.usbwifi.orconhosting.net.nz/catcurve.jpg

    http://www.youtube.com/watch?v=Jht-s_i__AE

    Cantenna as feedhorn on dish:

    http://www.youtube.com/watch?v=vJwOpJjYKqA

    Check this out!

    http://www.youtube.com/watch?v=07U0j5BCuts

    And these

    http://www.youtube.com/watch?v=ozOMtqPOESo

    http://www.youtube.com/watch?v=IQoLFsIb7sc

    Now, software... if you have XP or earlier, you can find and download FREE a program called Netstumbler.

    http://www.netstumbler.com/downloads/

    If you have Vista, you can use Vistumbler.

    http://www.vistumbler.net/

    These are tools for finding and connecting to access points.
    Last edited by AE5JU; 08-30-2009 at 04:11 AM.

  10. #20
    Join Date
    May 2007
    Location
    Etna PA
    Posts
    2,894

    Default

    Be careful when selecting a can for the waveguide.

    If you chose a can that is too small, the antenna will have poor gain due to the Waveguide beyond cutoff effect (scroll down to fig #2)

    Too big a can , and the gain will fall, but nowhere near as fast as when the can is too small.

    And as far as putting a dongle right at the feed of a dish, That's a very very poor way to illuminate a dish.

    The dongle is omnidirectional, most of the power never reaches the dish to be focused.

    Instead, you want to design a waveguide feed that will evenly illuminate the dish. One where the -3db beamwidth of the waveguide matches the angle the dish subtends from the feed.

    Note the f/d (focal length/diameter of dish)of the dish comes into play when selecting a feed.

    Also, be aware that with narrow beamwidth antennas, it's important to be able to adjust the elevation, as well as the azimuth for best results.

    Rege

    Rege
    Now my mistakes travel at the speed of light!:cool:

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