[kismac] Re: Cantenna_anyone using something like this?

  • From: "Ray Dios Haque" <ray@xxxxxxxxx>
  • To: <kismac@xxxxxxxxxxxxx>
  • Date: Sat, 15 May 2004 16:12:04 -0400

> I had looked at various directional and gain antennas but soon realized
> that at 2.4GHz the coax and connector losses are going to eat up most
> of the gains unless you keep the coax real short.

Don't waste $50 on something that would cost you less than $3 to build.  You
can make a very respectable cantenna with a couple of soup cans and a
connector.  Check this page for a nice illustration of one ...


The dimensions are important!  It should be 3.25 inches in diameter, and a
little more than 7 inches long.  You can get away with connecting two cans
bottom to top to form a nice long barrel (I held mine together with duct

Just about every one I have seen uses the N type connector (CD/Radio Antenna
style).  Those connectors will run you five bucks, and for their size have
lots of loss.  Also as Dan mentioned, the longer the cable, the more loss
you will receive.  I decided to go with BNC connectors myself, and I ended
up hacking apart a few wireless cards and adding a BNC connector to them.
It also helps to have a crimper that will do BNC connectors.  I was able to
make a 3 foot cable, BNC at both ends with solid (not stranded) copper core

With my cantenna, and a line of sight path (no obstructions) I can sniff
signals from a full mile away (or more).  The signal you get with a cantenna
can be deceiving, and it's hard to pinpoint exactly where it's coming from.
Also, you usually cannot send signals as far as you can receive them.  In
other words, you may be able to sniff traffic from an AP, yet not join the


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