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Wi-Fi Cantenna (2.4GHz): How-to Make a Long-range Wi-Fi Antenna

Create a cantenna to drastically extend your Wi-Fi signal!  Works great with a router that has external atennas, like the old-school classic WRT54G.

Requirements For This Walkthrough


  1. A wireless router with external, removable antennas, preferably with custom firmware or a wireless USB dongle with a removable antennta
  2. Mac or PC
  3. Empty 1qt baby formula can or other similarly-sized aluminum can
  4. Female N-connector, chassis-mount
  5. RP-TNC-to-N-male cable for connecting to most routers (a.k.a. pigtail) or an N-male to RP-SMA-male cable for connecting to USB adapters
  6. Screws (sometimes they come with the chassis-mount N connector)
  7. 12-gauge copper (if you have scrap cables, you could also unsheath them and see if the copper wire is thick enough to fit into the N connector)
  8. Soldering iron (a fine-tip with lower heat works best)
  9. Solder
  10. Wirecutters
  11. Screwdriver
  12. Digital (preferred) or analog calipers; or just a tape measure
  13. Can opener (or something to remove the lid with)
  14. Fine-tip Sharpie or other utensil to mark the location of the screws


  1. None

Knowledge, Skills, and Abilities

  • Ability to solder
  • Ability to install components with screws
  • Basic understanding of wireless networking concepts (radios, wavelengths, frequencies, etc.)


How the Cantenna Works


The aluminum can acts as a medium for the radio waves to be guided through, hence the term waveguide cantenna.  Radio waves will be “guided” into the can and interact with the wire element, which sends a signal down the pigtail cable and then to your computer or router.

Dimensions of the Can Matter

Each radio frequency has a different wavelength.  The wavelength of a signal is the velocity of the wave divided by the frequency.  If you can, imagine you can create waves in a small pool.  The velocity is the rate at which the wave changes position.  The frequency is how many waves you can make in x amount of time.  The wavelength will be the distance between each wave you produce.

Now imagine you want to catch some of those waves in an aluminum can.  If you make really large waves in the water but have a really small can, you won’t catch many or they will just break up.  If you can perfectly match the size of your waves to fit inside the can, you will get capture the most water, or in our case, a wireless signal.  The only difference is that radio waves are invisible.  In order to find out the right size of the can, we need to do some math.

Guidelines to Cantenna Dimensions

There are a few basic guidelines to follow when making a cantenna.  This will also help conceptualize what to do when making it or if you are modifying the can for a different frequency.


  • The length of the can should be longer than 3/4 of the wavelength
  • The diameter of the can should be longer than 1/2 of the wavelength
  • The copper element should be approximately 1/4 of the wavelength
  • The copper element should be x millimeters away from the back of the can (rear standoff)–this is based off the overall diameter of the can.  Use this calculator to determine this

There is an online calculator, which will help you determine the dimensions of your cantenna.

Formula for Calculating the Wavelength

First, it is important to know that radio waves travel at the speed of light, which is about 300 Mega meters (Mm) per second (the exact speed is 299,792,458  meters/sec).  For the purposes of an easy-to-remember formula, I rounded up and converted meters to Mega meters.

Wavelength (mm) ≈ Velocity of wave (Mm/sec) / Frequency (GHz)

w = v / f

We know v will be 300 (rounded up based on the speed of light mentioned above).  For f, we need to plug in the Wi-Fi frequency.  You could just use 2.4, but in order to be a little more accurate, we will use two more decimal places.  For channel 6 in the 2.4GHz spectrum, we need to plug in 2.437.  Solving for w then yields ~123mm.

w = 300 Mm / 2.437 GHz

w = 123.102175

Now that we know the wavelength for our radio frequency, we can begin calculating the dimensions of the can based on the guidelines mentioned previously.

Breaking Down 2.4GHz into Smaller Pieces

If you are confused about using 2.437 instead of just 2.4, take a look at the chart below to see how each channel has its own frequency.  Or if you are feeling very bold, examine the Radio Frequency Allocation chart, which gives a very broad but complex overview of all the available radio frequencies.  Basically, just know that the 2.4GHz spectrum isn’t just 2.4GHz, it is actually 2.401 to 2.483.  While this may not seem like much, if you have ever changed your wireless routers channel to get a better signal, you know that it does make a difference.

Finding the Wavelength of Any Frequency

Making cantennas to work with any wireless signal

2.4GHz is a common frequency for Wi-Fi and its wavelength makes the canntenna an ideal size–not too big, but not too small.  Once you start working with other frequencies, the cantenna might become ridiculously large or impossibly small.  But simply using the formula above, you could theoretically make a waveguide antenna for any frequency.

Creating the Cantenna (Step-by-step)

Dimensions for the Can

The size of the can will make a difference on the quality of the signal.  I will be using numbers from the How the Cantenna Works section above to calculate the dimensions.

If you were able to find the same can that I used (a 1qt Enfamil baby formula can), then you can simply follow the instructions below.  If you have a different sized can, you will need to calculate the dimensions based on instructions above in the How the Cantenna Works section.  You should still be able to follow along, but any specific dimension steps will need to be modified to suit your can.

Clean the Can

  1. Empty the can by using its contents as intended (give baby formula to a baby; drink juice; or consume food that the can contains, etc.)
  2. Clean the can
  3. Remove one of the can’s lid
  4. Remove the can’s label

Prepare the Can for the N-connector

  1. Measure ~63.5cm or ~2.5in from the back of the can (this will be different if you are not using the same can that I did)jacob_salmela_cantenna_element_measurement
  2. Mark this location with a Sharpie marker  Note: This will be the location of the copper wire element
  3. Drill or cut a hole into the can making sure that the center of the circle lines up with the measurement above.jacob_salmela_cantenna_element_measurement_marking
  4. Drill four screw holes into the can using the N-connector as a guide for their locationjacob_salmela_cantenna_element_hole

Cut the Copper Element to Size

  1. Cut a piece of 12-gauge copper element to a slightly longer than 31mm (this will be different if you are not using the same can that I did)

Note: This part is tricky because it needs be 31 mm from the point it exits out of the N-connector.  In order to solder it into the connector, it needs to be a bit longer.  I suggest cutting a larger piece, fitting it into the connector, and then trimming it down after it is installed.


Solder the Copper Element into the N-connector

Once you have the copper element cut to size, it needs to be soldered into the connector.  If you have never soldered before, learn how, and then cut a few pieces to practice with before working on the actual connector.

  1. Solder the copper element into the N-connector

Caution: Be careful not to melt the plastic contained in the N-connector.  It melts easy, so I would suggest using a soldering iron that has lower heat and a fine-tip.

Attach the N-connector to the Can

Once the N-connector is complete, you are ready to mount it to the can using the four screws.

  1. Screw the N-connector to the can


Connect the Cantenna to a Wireless Router or Wireless USB Dongle

Your cantenna is almost done; just connect the pigtail cable from the cantenna into a wireless router or wireless USB dongle.  The router or dongle needs to have a removable antenna.  The picture below shows the classic WRT54G being used.  The great thing about this router is that you can add DD-WRT firmware, which will give you the ability to choose which antenna is transmit and which is receive.  It will also allow you to adjust the power so you can increase the range even more.

  1. Screw one end of the pigtail into the cantenna’s N-connector jacob_salmela_cantenna_with_pigtail
  2. Screw the other end into a compatible router or USB donglejacob_salmela_cantenna_hooked_to_wrt54g

What to Do Next

25 replies on “Wi-Fi Cantenna (2.4GHz): How-to Make a Long-range Wi-Fi Antenna”

You should use this calculator to find all of the dimensions, but using the formula I provided. Your wavelength is about 693, so your element needs to be 173mm. Use the calculator to get the rest of the can’s dimensions.

1) What is the dimensions of your 1qt Enfamil baby formula can?

2) If I made a mistake in hole placement, can I cover it with aluminum tape and drill another hole?

1. I don’t recall. My cantenna is long gone…
2. You can and it probably won’t make much of a difference. However, the cantenna does require the reflective properties of the can to function its best.

Your article has been the most detailed description I could find on the net. Thanks a lot for sharing.

On many pages people recommend adding a Yagi collector inside the can. While at the same time ignoring any details of the optimum can size. Would there be an advantage adding one to the design?

I have seen others do this, too. I can’t provide much feedback as I haven’t done it myself.

very cool…..Ii just got my CHIP a couple weeks ago and was looking for resources to help me learn the terminal language but Ive gotten sidetracked here looking at all the cool stuff here…..GREAT RESOURCES HERE

Thank you for this guide and for continuing to respond to comments. I have a can which has a lip which comes 1/4″ in from the outer diameter of of the can all the way around. If I use the inner diameter I get a measurement that, according to the calculator, won’t work well at all. However, if I use the outer diameter measurement then my can is well within an acceptable range.

How much will this lip affect the entry of radio waves into the can? Which measurement should I use, or should I use a different can?

Thanks again

You’re welcome. I have always found the cantenna (and other projects on my blog) long-term fun, so it’s always interesting to keep up with users that interact with me long after the post has been published.

If you think of the radio waves like waves in the ocean, it may better help understand how the lip of the can may affect the signal. From what you are describing, the lip sounds like it the waves will enter the can, but will get distorted a bit from the lip. If you were to send a water wave into that can, the wave would grow or distort when it hit that bump in the can and may not be the correct “height” when it reaches the back of the can and hits your element.

Take that information as you will. In my example, the can has several ridges, so it’s not perfect to begin with. A smooth, shiny surface works best for a cantenna, but this limits your options and I had a hard time finding one that was perfectly smooth and shiny inside. That being said, of the two different cans I tried–the pineapple juice one and the formula one–the results were similar but not exactly the same.

I hope this helps a bit.

An accessible metaphor! I think I’ll go ahead and give it a shot, I bought two connectors so I could make two cantennas and compare them. I still haven’t perfected my soldering, I gave it a shot yesterday and my solder just slumped off of the joint – back to the books (or videos, as it were).

Thanks again for your time!

Excellent tutorial!! Thank you so much for taking the time to post all the details and information. I need to extend my signal 300 yards away from my router. I plan to have two cantennas pointing to each other at each end. Any thoughts or tips? Thanks again!

Just make sure they line up as perfectly as you can get them. You may want to use a signal monitoring program to verify you have the strongest signal possible.

Could you greatly extend the capabilities of a cantenna by fixing it to the focal point of a parabolic reflector (old satellite tv dish) facing the reflector? Theoretically this should work but I haven’t seen anyone do this. Also I’m still a little confused at what the optimal diameter of the can should be. In your picture is says half the wavelength but in other posts I see about 3.5 in is best. According to you it would be half the wavelength of about 2.4 in (complete coincidence that its for 2.4Ghz)

Yes, I’m actually working on creating a parabolic reflector cantenna and will be documenting my process.

It’s been a while since I made the cantenna, but it was a research project for school, so the information I found was online in the various articles I linked to. I can’t say the optimal diameter without going back over my research (which I will likely need to do when I write up the bi-quad version of it).

Hello jacob, I would like to know how far can it get, I have heard around 2 miles away, Have you tried that distance? How far do you think it can get?

This is very cool. think I am going to try and build two of these. But I cannot find any tutorials on the setup. Is the WRT54G router still capable of acting as a local access point with its second antenna while utilizing the long range directional antenna?

Its simple enough to put it in some repeater bridge mode thing to have it connect to a far distant antenna with the directional can. But then from what I understand it only has the ability to use one antenna at a time so is it smart/powerful to switch back and forth multitasking two separate networks? Or how is the router used now that you have connected it (to a source of internet, presumably) in the far distance.

I think you can accomplish most of what you want if you use a third-party firmware. It lets you control antennas, power output, and more.

Jacob thank you for your help in this matter what do you think of making 2 cantenna’s and joining them side by side with a wireless repeater between them of course the lines would be protected from the ground plane, so do you think it would be powerful give me your input on this ok…

Lorin A Randall (Bo)

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