Various Cantenna Builds

Here is a classic project used to increase wireless signal strength. Cantennas focus using a waveguide very much like a magnifying glass focuses light. [Robert] made a Natural Light beer cantenna, pictured in the upper left. His approach used three beer cans, a paper towel holder, and a shower curtain rod. On the tipline, he noted a signal boost from 11Mbps to 54Mbps. This is certainly something we can hack together if our room lacks adequate signal. Read about parabolic and seeking versions after the break.

The lower right image is an example of a parabolic soup cantenna constructed using an old satellite dish. No figures seem to be cited, though the construction is worth noting. We’ve had success with old satellite dishes in the past. The upper right and lower left pictures are scanning Cantennas. They use servos to seek out stronger connections by moving and checking the signal strength. Below is an in line video of the lower left cantenna while scanning. Maybe you want to know How to build a tin can waveguide WiFi Antenna. All the instructions are provided complete with a rough cost break down, and the site has a calculator to determine cut off frequencies given a can’s diameter.


27 thoughts on “Various Cantenna Builds

  1. the stronger the connection, the fewer dropped packets, resulting in a faster connection. so you can measure it in decibels, but you can also measure it in amount of data transfer possible.

  2. that’s sort of like measuring different kinds of gasoline in mpgs instead of octane.

    it certainly is more helpful to the layman, but only for that particular scenario – where as octane, or I guess decibels in this sense, is more of a constant that lets us know about the actual performance.

    the nati-light antenna is just a picture and alot of the links are to general faq pages – are there any writeups on some of these other particular listed projects?

  3. Everyone wants to make it harder than it is…addictronics has the basics!

    Take a 15+inch alum mixing bowel, put a hole in the bottom center. Put a dowel thru it along with a usb extension cable. On the end of the dowel, tape a wifi usb module and plug it into the cable. Duc tape this to the top of a mount; camera tripod is best. Hook to computer and slowly move dowel in or out till max receive signal…(focus) tape it in this spot.
    Add on 2, 3 ,4 extension usb cables as needed to a max of about 25-30 feet. Remember , all digital processing is done in the module, so there is very little feed line loss to the computer.
    Gain as measured here is in the range of 15-22bdi based on bowel diameter/bowel shape/depth…
    It took longer to type this than make on :)

  4. tom mac:
    It’s all very interesting, but you’ll never convince me that the gain is based on “Bowel Diameter” unless you’ve been putting that antenna where the sun doesn’t shine.
    I need to build one of these anyway.

  5. Just know that you can have the worlds greatest powered super gain antenna plugged into your receiver and it would only be a small step above anything else – the performance is mostly dependent on the transmitter, and building a receiver antenna only increases your chances of picking up a signal.

    I’ve tried the usbdongle + veggie strainer and it’s not that much of an improvement, imo. Plug a cantenna into your router running DD-WRT and watch the magic.

  6. this is an old promising trick for wifi, but how well would it work for cellular phones using a external antenna with no repeater. The external antenna i got is on the roof an i don’t feel like getting up there because its currently raining.

  7. Little tip for everyone. I used to work at the MIT FabLab in Accra, Ghana. For any decent cantenna set up (especially point to point), or for finding the apex of a dish. You have got to get one of those handy green lasers. Attach the laser to one antenna, and a graticule to the other and, presto.

  8. @xrazorwirex

    Not to nit-pick, but octane is gasoline’s resistance to detonation due to pressure and has nothing to do with MPG.

    I can’t think of a better analogy atm though, sorry.

  9. got out an old sat antenna and put my umts stick where the lnb is, and targeted the next umts station, but the signal didnt get better, what did i wrong (does the stick need a can as housing?)

  10. Boy, what a diff a little “e” makes :)

    Not dealing with a perfect parabolic shape… just make do with the best focal point, some bowls are just shaped better for focus.

    Also ,Tx power isn’t changed, but the Effective Radiated Power is.. as it’s power is also directed to a narrower angle ( not omni ).

  11. @dstrcto

    yeah, the point was they are completely different things and to use the end result instead of a constant isn’t good for measurements since it would be different for each person – it’s like saying “I use 25mpg gas” instead of saying you use premium; it wont be 25mpg for the guy in the F-450…

  12. @ arrangemonk, If the lnbf arm is an edge mount then you need to compensate for elevation. The dishes that dish network and directv use don’t actually see the signal coming in directly at the face but from 5 degree’s (might be less or more, just woke up and heads fuzzy still)above. For instance the standard dish that Echostar uses to say pick up signal from 110E would have an elevation of 30 but the signal comes down at an elevation of into the face of the dish at 35 degree’s. Knowing the elevation of your source transmitter will help but you will run into a problem with the elevation settings on the dish assembly not having ticks any lower than say 25 so you will have make your own markings to go lower. Once you have that done and the elevation set to 5 degree’s below that actual elevation of the source you just need to face the dish in the direction of the source and fine tune, the nice thing about these dishes is they have allot of slop built into them to get signal from sats and as such should work well.

  13. BTW, there was an article in either pop sci or pop mechanics two or three years ago where the dish method was used to successfully transmit and receive a signal over 12 miles in the California desert.

  14. Pfft, californian desert, dry air and no obstructions whatsoever and no competing signals either, what does that mean to you and me really? Nice to know for if we ever get banished to a shack 12 miles into the desert I guess :)

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