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Cantenna w/ Funnel
hardware : by Tommy - April 4th 2007, 11:20PM
Finally. Yes, I finally got around to making a cantenna. Years ago I read about the now famous Pringles Cantenna which I've always thought was a cool concept and has been something I've wanted to do. Now it's a bit of use to me since I enjoy using my laptop on the move using NetStumbler to locate open access points.

I began with a bit of reading and looking up what all is needed to construct a Pringles cantenna, and before long I learned that the Pringles isn't really the best way to go. Nope, instead I found that the Pringles design was out performed by a Cantenna made from a can of beef stew! Not only does it perform better, it's way easier to make. In fact, after buying the ready-made 1.21" radiating element from jefatech.com, this construction was probably the easiest project I've attempted. I found out that a large can of Dinty Moore is the same size as the "Nally's Beef Stew", so guess what I had for dinner one night? I cleaned out the can, and went to the machine lab the next day to use a drill press to pop a 5/8" hole for the N-connector. Took it home and tried it out. Wow! I went from seeing 1 AP (mine) to 20, just in my front yard. Not bad for just a can with a connector on it. I then took a stroll to see what the neighborhood has to offer and found an open Netgear access point. After zeroing in on the source, I found that it was about 120yds from my original location and across a street! (...and that was being able to use it, I was able to detect at a further distance.)

Fine and dandy, but the can just wasn't good enough on its own. I had to do more. I added a 6"-to-4" heat pipe coupler to the front end to funnel in more signal, which I had seen on a cantenna made from a Pirouette can. (Yeah, I made one of those too. Just today, in fact.) The funnel gave me a noticeable difference in signal strength when I'm at a distance. I think I remember seeing it jump about 3dB in signal strength after I slipped it on. (That's a doubling of power!)

In case you missed the links:
  • Here's the original can.
  • Here it is with the funnel (kinda looks like a flashlight)
  • Inside the cantenna (radiating element is about 1.21" long)
  • The new Pirouette model (yet to be field tested)

    Grendel sez: For those wanting to make one too, I just learned that the large 40oz can of Walmart brand ravioli comes in a similar can and it's a couple bucks cheaper. (guess it depends on how much you like beef stew vs. ravioli.)
    FYI - Can dimensions: 3.9" diameter, 6" long
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    + Corey T.
      Apr 05, 2007 11:30
    That is pimptastic, sir.


    + Tommy G.
      Apr 05, 2007 12:55
    I also just found this video about some really goofy ham radio guys in Mississippi that made an "active cantenna" by taking apart a USB Wireless adapter and mounting that antenna in the can. The benefit here is the RF goes right to the NIC, and the USB cable carries data over the distance. This amounts to less signal loss due to the coax cable.
    Video link here


    + Tommy G.
      Apr 05, 2007 13:17
    They try out the cantenna and show you their results on Episode 4.
    Video link here


    + anonymous
      Apr 05, 2007 14:47
    Maybe the really goofy ham radio guys in Mississippi are in fact really semi-smart commercial radio guys too. (I didn't have any money invested in WorldCom...) In episode 10 we added a DirectTV dish. http://www.amateurlogic.com/blog/


    + Tommy G.
      Apr 06, 2007 03:36
    Speaking of wireless, here's a pretty good deal:
    USB wireless b/g stick for $15, free shipping from Newegg.com


    + James S.
      Apr 06, 2007 10:30
    I made two of those Pirouette models back in 2004 to use to connect my house with a neighbors house down the road for some Xbox gaming. They worked rather well. Here is the google cache (wiki got hacked or something) for the howto I used.


    + Tim L.
      Apr 06, 2007 20:19
    I have several Dish Network dishes stashed for just this sort of thing.


    + Tommy G.
      Apr 07, 2007 00:44
    I have a dish mounted on a 2x4 base that I made. (sturdy, but portable)
    The dish came from my mother-in-law, and I found that the local Dish Network sales office has a nice stash of old dishes behind their office. They only want the "guns" from them, not the dish, but when customers bring them the whole thing back they just pile them up out back. He said I can come get them as often as I need, just to come in and tell them I'm getting a couple. w00t!

    I spray painted mine black so it looks more sinister and less hokey. I also sprayed my callsign on there so it looks official in case someone important were to ask me why I'm aiming a microwave dish at various places.


    + Tommy G.
      Apr 07, 2007 00:53
    Oh yeah, I'll post more about the dish early next week after I try it out on my new card: the ZCom 300mW, dual RP-MMCX. (birthday present to self)

    It's useful for making long distance shots. (Not that I have an 8' dish to use...)


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