DIY Wifi Extender - Cantenna Build With a Stand.

by budgethackdotcom

248K26626

Intro: DIY Wifi Extender - Cantenna Build With a Stand.

This antenna is one of the easiest and cheapest things you could build to extend the range of your wifi network.  Most of the materials are probably sitting in your cupboard right now so it really can be built on a shoestring budget.

Bill of Materials:

Two milo tins or similar
F-Type chassie mount
Pig tale for F to Sma
Short piece of copper wire

Tools:

Tin snips
Can Opener
Soldering Iron
Drill
Drill Bit

Original content avaliable at  BudgetHack.com

STEP 1: DIY Wifi Extender - Preparing the Cans

Now you can build your cantenna with just one tin but chances are you wont meet the suggested overall minimum 3/4 wave length required when using the centenna calculator.  So first thing to do is go to the cantenna calculator and enter the diameter of the opening of your can in mm.  You will see the overall length on the can down the bottom,  if your single can is too short then you will need to use two, Don’t worry if you a little over or under length but it should be fairly close.

Alright then what we want to do is remove the top of one can and the bottom of the other.  Once you have done this on the can with the top removed cut out a small strip approx 10mm across and 15mm down the can.     Then we are going to use this slit so we can push one can inside the other, The can with the slit will deform slightly but don’t worry about it at this point.

STEP 2: DIY Wifi Extender - Joining Cans

Next we need to heat up our soldering iron as we are going to solder these cans together,  You want your iron HOT I put mine on around 400 C and this seemed to work great.   First thing is to tack the can in place with a few small solder joints then make sure your cans are straight and run a good solder bead all the way around.

STEP 3: DIY Wifi Extender - Finishing Edges

Once the solder joint cools you will see the inside of the can is a bit raggard and raised.  For this I just got a large socket on the end of an extension bar and used it to hammer the raised edge down, with a bit of work you can get the inside of the can fairly flat.

STEP 4: DIY Wifi Extender - Main Element


Next from your calculator measurement find the height of your main element,  Cut a piece of copper wire this length and solder to the top of the f-type connector as shown below.

STEP 5: DIY Wifi Extender - Attaching Main Element


Last thing to do is have a look at your calculations again you can see the distance the element should be from the back of the can, measure this out on the can and drill a hole big enough for it to go through.  Once the mount is in place  go around and fully solder it to the can  like in the image below.

At this point you have a working cantenna , Connect  your piggy tail between it and your wifi card and you are good to go. Remember this is a directional antenna so it needs to be point in the direction of the AP your trying to connect to.

(Note:  Some people have advised they had  trouble finding the pigtales and connector’s so I’m trying to locate a bunch so I can make them available on BudgetHack.com)


STEP 6: DIY Wifi Extender - the Stand

Now what about this stand business,  this really was me just mucking about but it turned out to be quiet useful.

What you want to do is take the bottom of the tin you cut off and cut three small triangles out of it evenly around its circumference,  bend the remaning triangles down to make a sort of tripod shape.   Then you want to bend them in the middle so the corner of each triangle touches then solder them together,  now just solder it to the cantenna.  This might seem a bit silly but it really helps when trying to point the antenna and it costs you nothing.

Alrighty your probibly wanting to know  was it worth the effort well for me yes.  I have not had a chance to do exensive testing,  but from some basic testing it seems to be giving me a 15db increase over the stock d-link antenna which is certainly a massive increase for the minimal cost of the build.

25 Comments

docman100 6 years ago

Is the a possible way to make this connect to an AC Outlet? and boost up multiple instead of one device at a time?

astral_mage 10 years ago

ok here the proper link. and it ask if u wanna take the risk of letting the app run or not. but long as yr av is up to date hen u'd have no problems
http://kioan.users.uth.gr/wireless/cantenna/

astral_mage 10 years ago

if u braze . like yr doing copper pipes uill get it done faster

astral_mage 10 years ago

umm plz fix the link. it takes me to a malware? site

mnc_co_uk 13 years ago

I've used a similar design myself with good results. Impedence matching is an important part of the design. The whole of the transmission line, includung the antenna requires impedence matching. when building home brew designs like these demensions will differ from the blueprint.
Using some rf decouplers and high frequency diodes and an oscilloscope it is possible to measure the SWR.

A good match between your antenna and transmission line will result in a low reflected wave. If the reflection is high compared with the foward wave there is a bad match, poor performance will result and the dimensions of the antenna would need altering.

when building a killer antenna impedance matching shouldn't be taken lightly and it's good to know, if you spend time getting this correct, you'll be getting optimal performace out of your hard work.

Dr.Bill 11 years ago

If impedance of the antenna is too high or too low, the transmitter (router) will see the antenna as ah dead short resulting in high SWR that can burn up the final amp in the router transmitter.
So impedance matching is Very important. MFJ sells an SWR and impedance analyzer that will tell you when your antenna is perfect. MFJ-259B

susovit 12 years ago

I want to try this out but the cantenna calculator is lost???
The link doesnt open the calculator. ????

frogman31680 13 years ago

Interesting. Sorta like the pringles cans I have seen around.

I wonder if having a smooth interior or the ribbed kind affect the signal in any way.

Also, I don't use the coax connector for my wifi. I have a USB adapter... So i would have to adjust this somehow.

Slim49 12 years ago

According to my reading & due to the length of the 1/4 wave form,
the interior ribs will not be "seen" during the proprogation of the wave.
mine all worked A OK.
Mr. Steve

Slim49 13 years ago

Dude,
this one is so easy to do.
need a 18" USB extender. I wrapped a 1" band of aluminum around with 3" of handle below. the ribs are so within the shortest lenght of teh wave as to be no issue. made 2 of these. my friends rave over it.
get a 4" + or- can, I used a tomato juice can.
estimate where the face of the interior trace antenna is & its front facing direction.
cut a slot in the can 1.25" from the rear wall. need a friction fit of your USb donagel.
insert it up inside 1.25" or more, play with it.
You will get some "much improved" signal strenght & more signals that you could ever imagine.
I have built every one of these Wifi antennas.
Mr. Steve

gora_ji 13 years ago

Sounds really good... some of it I couldn't understand though.

How about an instructable????! ! ! !

Slim49 13 years ago

Go here:
www.turnpoint.net/wireless/cantennahowto.html
its teh best site of all.
read up at several sites.
search for : CANTENNA, lots of info already is out there.
even just getting the USB donagel inside most any can will jump up signal strenght & numbers of sites.
Luch,
Mr Steve

Javin007 13 years ago

Posting another completely different website on how to make the exact same thing is more than a little rude. Particularly when you add insult to injury by saying "its teh[sic] best site of all."

And as a side-note, having actually looked at this site, I can certainly say that no, it's not.  And this instructable is far superior.

Slim49 12 years ago

Whoops!
no insult intended!
I used elements off you instructable.:-)
Mr steve

k4gdw 13 years ago

I've never built one of these before, but as to your question about the coax connector, if your USB WiFi adapter has an external antenna connector, you'll need a coax jumper with the same kind of connector as is on your WiFi adapter. If you're adapter lacks an external antenna connector then I'm not certain how you'd be able to do this. You'd still need coax and you'd need to crack open the WiFi adapter and locate the antenna. Find where it connects to the board and solder the center conductor of the coax where the antenna connects and the coax shield would need to connect to ground. Assuming you were able to identify where to solder the coax, and are skilled enough at working with surface mount boards, it MIGHT work. However, you're just as likely to ruin your adapter.

Working with antennas isn't just a simple matter of hooking it up. A transmitter is designed for a specific impedance, measured in ohms. I'm not going to go into a treatise on antenna theory. A transmitter is designed to use an antenna system that has a specific impedance. If the antenna system's characteristic impedance doesn't match the transmitter, then you have an impedance mismatch which can, if the mismatch is too large, cause physical damage to the final transistors in the transmitter.

budgethackdotcom 13 years ago

Thanks for your replys, as far as the ribbing on the can I dont thing this is an issue because if you look at the opening of the can there is actually a lip which I think will compensate for the fact the inside isnt smooth. Also with the impedence if you use the correct 50 ohm cable etc the impedence should be fine also the transmitter should have an impedence matching circuit to prevent damage. Some of the usb wifi adapters can have an external antenna connector added as ive done this before but your right you have to be real careful.

madworx 13 years ago

awesome @_@ hahahaa..

nicky23 13 years ago

Nice stuff. As I am on budget and want to connect with my friend with wireless I am thanking you for this post and I am off to create the cantenna.
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