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DIY Tin Can Wireless LAN Antenna 2.4GHz




Read how I build my home made 2.4GHz WLAN Antenna
using a used tin Can here (IDIOT PROOF DESIGN)



Tin Can 2.4GHz WLAN Antenna
by Judhi Prasetyo (judhi_prasetyo@yahoo.com), 23-June-2003




Foreword

I have seen some great 2.4GHz Antenna designs o­n the Internet that are using used tin Can or Pringles Can.

The o­nly thing that put me back from following them is because ALL of those designs are using pig-tail cable which is verrrry expensive to me and difficult to find.

So I decided to build my own Antenna using similar concept by eliminating the need of using pig-tail cable.







Disclaimer

I am not responsible for any damages, injuries, problems or whatsoever caused by your action in following the information o­n this page, including any damage, loss of profit, loss of life, and loss of dignity caused by usage of the tin can. Antenna built based o­n this information.

If you get cought tapping other people's WLAN using this Antenna, please blame it o­n the rain!


What you Need

1. Tin Can.

You Can use any tin Can with diameter of around 3.5" or 9cm. The taller the Can the better.

I use GOLDEN BOY Wasabi Coated Green Pea tin Can. Not o­nly the size is suitable, but the content fits my taste and comply to my halal diet.

Just take your time to walk through your nearby favorite supermarket, I am sure you'll find something similar that fit the measurement and your taste.




2. USB Wireless LAN card

OK, here's the trick why I do not need pig-tail cable:

I DON'T USE PCMCIA CARD!

Instead, I use USB WLAN card model 741 from Gigafast.

You Can use any other brand or models as long as the Antenna is detachable.

With this card, you Can eliminate the RF loss at the RF cable (because there's no RF cable!) and Can go up to 10 meters away from the PC via USB cable.



3. Hard wire

You need this hard wire to replace the Antenna. Basically we are going to build 1/4 wavelength Antenna (for 2.412MHz this turnout to be 3.1cm or 1.24"). Make sure that the wire Can fit into your USB WLAN card's inner connector hole.

I found that the inner copper of RG58/U coaxial cable is good enough for this purpose.

4. Proper tools

For best result, prepare proper tools like ruler, marker pen, motorized drill, snip-plyer, etc.

Assembling

Poke a hole about 1.21" or 3cm from the bottom of the Can, then slowly make it wider using a drill. Note: this distance is subject to change, please experiment yourself by adjusting the hole distance until you get the best result. The hole should be just nice to fit in your USB WLAN card Antenna connector through it.

Plug the hard wire into the connector before you put in and secure the USB WLAN card to the Can.



I use blue-tac, something like synthetic clay to paste poster o­n the wall. In o­ne occassion in Australia when I have to demonstrate the Antenna, I Can't find blue-tac so I improvised using a chewing gum as replacement... mmm.. maybe Sugus will work as well.

You Can temporarily secure the position using rubber band or cable tie. This is important to make sure all stuff is in position when we do the fine tuning. Later, o­nce you are happy with the result you Can put more blue-tac, put a bolt o­n the connector or even glue to secure the USB WLAN card to the Can.























Optional Accessories



I realized that holding the Antenna by hand for too long is a bad idea. So I dig my old stuff storage and found a mini camera tripod. With some improvisation, I build a plastic bracket from old name card holder and mount the whole thing o­nto the tripod. Now it much better looking and a lot easier to do the fine tuning.

Testing and Tuning

You will need a reference Access Point or another WLAN station in Ad-hoc mode as the testing partner to do the tuning. The idea is to go a bit distance (100m) from the testing partner and aim the Antenna toward it.

Slowly move your Antenna until the signal indicator o­n your computer shows the best signal. I did not use any special software, just the default WLAN card utility from Gigafast which came with the card.

After you get the strongest signal, try to cut very little portion (0.5mm) of the hard wire and see how it goes until you get the best signal. If you cut too much, there's a possibility to get even weaker signal so you need to make another hard-wire element. There's no scientific method to do this, just use your feeling and experience to get the best result.

After you are satisfied with the result, you Can secure the mounting of USB WLAN card to the Can as described previously.

Free advise

I never really try how far my antenna can transmit or receive. But from experiment, I Can get some signals from housing area accross the highway which were not received by normal Antenna before.
And instead of just using this design for WLAN client, the same concept Can be applied to Access Point to transmit sectoral WLAN coverage.
I do not encourage you to tap o­n other people's network without any prior permission or jam other WLAN provider's network. Anything you do please do it at your own risk

FAQ

Q: Where Can I get the Can like yours?
A: Usually supermarkets have. But you Can use any Can with similar dimension and maybe you even get better result!

Q: Where Can I get the USB WLAN card like yours?
A: I bought in in USA but it is made in Taiwan, you Can try asking your nearest computer shop. Any USB WLAN card brand will do as long as it has detachable Antenna.

Q: How much does the USB WLAN cost?
A: Around US$50 o­n www.eBay.com

Q: How much does the Can cost?
A: Around US$2 o­n local supermarket. 

Q: How strong is your Antenna gain in decibell (dB)?
A: No idea, never measure it using professional tools.

Q: How far Can the WLAN goes with your Antenna?
A: Never really try before, but 1Km is certainly easy.

Q: Can you explain in more detail o­n installing the USB WLAN card to the PC?
A: Please read your USB WLAN card manual. It may vary but USB supposed to be plug-n-play.



Links

  • How to build tin Can wireless Antenna
  • The ARRL Antenna Handbook
  • A Tin Can Design with good theory information.
  • A free o­n-line book o­n microwave antennas
  • "Juice Up" your Tin Cantenna with a surplus satellite dish.
  • Spreadsheet for optimum Can size calculation
  • A Flickenger design coffee Can waveguide
  • A coffee Can waveguide with corrected radiator placement
  • A Hunts 26.5oz. pasta sauce Can waveguide that fell in the optimum size range
  • A Nalley 40oz. "Big Chunk" beef stew Can Waveguide


  • (EoF)




    (C) Judhi Prasetyo 2003, please write me should you need to copy this article.








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