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Now that you have finished drinking that last tasty cup of coffee, what do you do with the empty coffee can?

Go Wireless! That's what.

Here is an easy to build, accurate and powerful wireless antenna made out of an empty 13.5oz coffee can. Some soldering experience is required to build this project but if you can wield a soldering iron and a roll of solder, you can't help but turn out a well built antenna for long range wireless communications.

Step 1: Parts and Tool List

To enjoy great wireless, you will need at least one antenna. If you are planning to create a short haul project between two locations, make two antenna so you have a matched set.

Parts List

1) 13.5oz Maxwell House or any other brand tin can with plastic lid. (Empty of course).
1) 4 inch by 4 inch sheet of brass or tin.
1) 1 inch long by 1/4 inch diameter Brass tubing. (Any model or hobby shop).
6) feet of AIR195 low loss 50 ohm coaxial cable. (Available from air802.com. RG-58 may be substituted with marginal results).
1) SMA Female connector. (For connecting to your bridge or antenna jack. Available from air802.com)
1) Brass angle bracket. (Local hardware store).
1) 1/4-20 Brass hex nut. (Same hardware store).

Tools Needed

30 to 50 Watt Soldering Iron
Silver Solder
Solder Flux (zinc chloride or rosin type. not acid flux)
Coaxial cable connector crimp tool for 1/4 inch cable.
Drill with assorted drill bits
Black spray paint
RTV Silicone Rubber compound or Clear Silicone Bathtub Caulk
Sheet metal sheers
File
Sandpaper
'0000' Steel wool

Step 2: Calculations and Layout

Some Googling on the internet produced a number of Cantenna calculating tools. I chose this one because of its ease of use.

Any can will do but when you plug in the numbers you might find that you need to cut the can to the correct length before using it. The 13.5oz. coffee can is just right and works with no cutting required.

The frequency required is 2.437 GHz (or wireless channel 6) and the diameter of the coffee can is 3.875 inches or 98.4mm.

When you plug these numbers into the calculator, the length of the can is .75 x Lg or 135.75mm which is the exact length of the 13.5oz. coffee can!

Here is the layout with all the necessary dimensions.

NOTE: These are not exact dimensions but are close enough to give you results that rival the manufactured cantennas.

Step 3: Preparations

Step 1
Prep the can by removing the label and any remnants with alcohol or any adhesive remover.
Cut the ends from the can with a can opener.
Drill a 7 mm diameter hole 45 mm from one end of the can.
Wash the can thoroughly and dry.
Use steel wool to polish the end of the can which has the hole drilled in it.
Set the can aside.

Step 2
Using '0000' Steel wool, polish the brass tubing so solder will take to it.
Cut a 30 mm long piece of brass tubing from your stock and set it aside.

Step 3
Prepare one end of the cable by removing 60 mm of the outer jacket.
Cut the shield braid to 20 mm long, fold it back over the outer jacket and unbraid it.
Remove the center conductor insulation down to the shield.
Measure from the shield to the end of the center conductor and cut the center conductor down to 31 mm.
Set the cable aside.

Step 4
Use '0000' steel wool to polish both sides of the brass and set it aside.

Step 4: Solder Tubing to Can

Push the brass tubing into the hole drilled in the can, allowing only 1 mm to protrude into the can.
Flux the joint where the tubing and the can touch.
Wrap a piece of solder around the tubing creating a ring. Slide the ring of solder down onto the joint and melt it with the soldering iron.
Let the joint cool and repeat the soldering procedure on the inside of the can.
Using an acid brush, clean the joint inside and out with alcohol to remove any flux from the work.

Make sure your solder joint is shiny and new looking. A frosted or pitted look means that the joint wasn't hot enough. Reheat the joint and apply a touch more solder to fix it.

Step 5: Solder Can to Brass Sheet

Flux the end of the can closest to the tubing and flux the edge of the brass sheet.

Place the brass sheet on a fireproof surface and place the can on top of the brass sheet.

Solder the can around the inner and outer circumferences.

Set aside and let cool.

SOLDERING TIP - Use Silver solder in paste form to create a clean joint without having to mess with flux and solder.

Cut away any unneeded brass, file or sand even with the can edge.

Clean up your work with alcohol to remove dirt and flux.

Step 6: Solder Mount to Can

Turn the can onto its side with the brass tubing pointing straight up. Brace the can between two wood blocks to steady it.

Locate and place the brass bracket toward the outside edge of the can in line with the tubing.

Flux the bracket and can then solder the bracket to the can in line with the tubing as shown.

Let the can and bracket cool then clean with alcohol.

NOTE: A heat gun may give better results and provide better heating to the workpiece. Use rosin core silver solder for the best joint.

Step 7: Finish the Mount

Drill a 8 mm hole in the brass bracket

Flux the area of the hole and clamp a 1/4-20 brass nut in place over the hole.

Solder the nut to the brass bracket.

Let cool.


The mount allows the cantenna to be attached to a tripod for accurate aiming.

Step 8: Clean Up and Paint

Clean the can and bracket in alcohol to remove all flux and dirt.

Sand or file all rough joints and edges.

Mask off the brass tubing using masking tape.

Paint the outside with Black Rustoleum enamel. Do Not paint the inside.

Let dry for 24 hours before completing assembly.

Step 9: Cable Assembly

Remove masking tape from the brass tubing.

Push the cable into the brass tube until the center conductor insulation is even with the inner edge of the tube and only the center conductor is visible in the can.

Using the crimp tool, crimp the brass tubing around the coaxial cable to secure it.

Finally, apply RTV Silicone Rubber Compound to the inside rim of the plastic coffee can lid and snap onto the front of the antenna.

Let the assembly dry before proceeding with the next step.

Step 10: Connection and Use

Prepare the other end of the cable and crimp on the appropriate connector for attachment to your laptop, bridge or router.

Here I'm using an SMA connector for my mini bridge which will connect to my laptop.

To bypass the bridge, you could modify your laptop and add an external wireless connector like I did in the photo below which will allow you to connect the antenna directly to it. (I'll post an instructable on how to modify your laptop soon).

Step 11: Create Your Own Communications Channel

Short Haul Wireless

With two antennas, a wireless access point and a wireless bridge, you can create your own short haul network. Short haul wireless paths can be as short as 150 feet or as long as several miles.

Since there are 11 wireless channels to choose from, you could build several 'repeaters' and create a network up to several hundred miles. A repeater consists of two antennas, a bridge and an access point. The receive side or bridge side might operate on wireless channel 3 and the access point side might use wireless channel 9. In this way, you would avoid any interference between the two signals. With the correct selection of wireless channels to reduce interference, you could conceivably build a network around your entire city!

With the addition of a network switch, you could tap the network and use it as your internet connection. Check you local township ordnances as well as your contract with your internet provider for possible restrictions before launching a network building program between you and your friends.

The diagrams below illustrate the three short haul schemes that are possible.
Figure 1 shows a short haul network with an extended user.
Figure 2 shows a short haul network with an unattended repeater.
Figure 3 shows a short haul network with a split user and extended user.

Good luck and happy connections!

Raving Apache
Good
is there anyone that i could pay to be build me one these awesome extenders. i don't have ANY of these kinds of tools at my house. any takers. quote me a price....
In the early 80s HBO was broadcast to homes via 24GHz line of sight. I built a coffee can receiver (added a yagi antenna later). Had a phase lock loop to lock in the frequency. I think it was the first time my buddies back home didn't think of me as one of their dumb beer drinking buddies. Richard Prior, Ghost Busters all from a coffee can with a few electronic parts, hanging out the upstairs window.<br> <br> In the mid 80s is when HBO started suing people for it, somehow their signal beamed onto your property without permission was still their property. Big money ruled out squashing creativity. This was one of my first real hacks, legal until they changed the rules!<br> <br> The Yagi was a work or art, a brass rod with metal roofing disks soldered to it. I&nbsp;threaded&nbsp;at the end of the rod passing through 2 nylon disks for support, done to adjust the distance between the end plate and the receiver for optimum gain. This was when I knew something about analog, those days are long gone, not even a picture.<br> <br> Here is link of what happend when someone tried to go&nbsp;commercial&nbsp;with the hack. <a href="http://articles.philly.com/1986-01-22/news/26052731_1_dish-hbo-antenna" rel="nofollow">Coffee_can_HBO_CRACKDOWN<br> <br> <br> T</a>hanks for the memory!
&nbsp;<a id="fck_paste_padding" rel="nofollow">where i need to join the cable thet gose in laptop??</a>
Can I replace the cable with an Ethernet cable to plug unto my computer
&nbsp;where i need to join the cable that gose in laptop??
&nbsp;NO..... the cable is not shielded, has too many conductors and is the wrong impedance...... This needs a to be a shielded coaxial cable.
how much gain this cantenna has ,and how far is that?
betito4u I haven't calculated or measured the gain. Lately haven't had much time to do structables. Busy working to stay out of debt. Thanks for asking. Raving apache
Do you think additional gain could be achieved by incorporating a full wave rather than a 1/4 wave element such as described in the attached instructable ?<br/> <br/><a href="https://www.instructables.com/id/WIFI-Antenna-Hack!/?embed=flash">https://www.instructables.com/id/WIFI-Antenna-Hack!/?embed=flash</a><br/>
sounder Perhaps. The antenna was built tuned to 1/4 wavelength. How do you intend to measure the increase in gain? raving apache
burningsuntech, By comparing apples with oranges. Of course it would require constructing one of each and then testing to see which one pulled in the most APs with the strongest signals. I also assume that for the full wave version one would need to re-calculate the critical distance from the back of the can to element mount location. I do like your method of hard mounting rather than using a coax connector. Mechanical connections are always less preferable for signal transmission especially at microwave frequencies. Sounder
thank you I have looked at diy cantenna for a while and this is the first that I have found that did no use a n-female chassis connector. this was very helpful and I will be building one soon thank you
im going to buy a wireless adapter to connect to my friends wireless thats about a block away .. and i was thinkin of buying something cheap like the "ENCORE ENUWI-G2 IEEE 802.11b/g USB 2.0 802.11G Wireless Adapter" .. and im wondering will that work?
Where I live Maxwell is still using metal tins.
lol, i love the part where jef. was flaming me XD and it got removed thus rendering all my arguments invalid lol XD
ah, well, sorry :S cuz HERE they're made of metal :S umm hemmmmmm if u have an old tail/exhaust pipe/cylinder that should work basically the idea of this is to collect the wifi so any metal cylindrical item should work.
2words: Grocery Store :D but any metal tin should work...i think..
also, could you not put a usb cable on it and then run antenna software that expects a usb antenna?
fenris This is a passive device (supported by external electronics like a wireless card). Coax and USB cable are not the same and the antenna is designed for coax with a connection to a WiFi wireless card. I suppose that if you can find a usb wireless card to fit inside the can you could try it. After all. Discovery is what experimentation is all about. Good luck! raving apache
Indeed I do have such a thing, a Dell '1450 wireless USB adapter', that would fit into such a can very nicely. Is the can just a 'guide' or 'accumulator', then, or would I want to make some sort of connection to the can?
this is like a giant antenna for routers such as Linskys. They are as a monitor to a computer, only receiving information, not decoding. Your dell 1450 wireless USB adapter is as burningsuntech implied, an active device. It actually decodes and picks up the wifi whereas this antenna solely picks up the signal. hope that helps!
uh, i hope this is not too stupid, but why do you remove the metal end of the can and then go to a lot of trouble putting a metal end on the can? could you not just leave one of the original ends on there?
fenris No. Not at all! The reasons were to allow easier soldering of the tubing to the can for the cable insert and to prevent the rippled bottom of the can from detuning the antenna. Removing the bottom accomplishes both objectives. Will it work without all the fuss. Sure. But i'm anal and am a perfectionist
Far out. This sounds to me like exactly what I need. There is an unsecured connection that I detect, but it is apparently just far enough away that I am either not able to connect at all, or have only very minimal connection quality. Every other possible connection detected in my neighborhood is secured. I suppose I could try knocking on all the doors in my neighborhood until I find somebody who is willing to give me the sign-in key, but that is not the revolutionary thing to do at all.
Great and inexpensive idea... However, I am looking for a wifi signal booster that requires on direction to my Powerbook. I have seen such a thing and cannot remember where/how it is done... Any help out there will be appreciated...
if you wanted to optimize wireless even more could you wrap inculcated wire round the tin several times ?
Philipster Since we are talking about microwave frequencies here, the gain may be increased by designing and adding a horn to the end, though I do not know how much gain will increase by doing that. Adding any metal around the tin would likely do no good as the wire and the tin would both be at ground potential. raving apache
Very Nice Instructable! Looks Great!
Thank you.
Does this work with a macbook????
meddler This antenna is strictly passive and can be used with any laptop, wireless router, access point or bridge as long as you have the proper connector to interface with it. raving apache

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