Hi James: These antennae work fine and I am sure the coating over the metal is not causing your trouble.
The most complex part is the antenna feed. You can't just worry about the center conductor in a coax cable. The RF will not move in a predictable manner unless the coax cable is properly configured to maintain its symmetry, especially at the connectors. Lack of symmetry will mean a high VSWR and thus a high lose of radio energy. A good antenna book will show you how to do it, but basically it is following the procedures on this website. http://www.hometech.com/learn/coaxterm.html The higher the radio frequency, the more carefully you have to be, because the wavelength gets shorter meaning the mechanical tolerances must be held tigher. At these frequencies and with very small cable, connector construction can be tricky. I suggest you spend the $20. The antenna design is fine and does work. Even when it is completed with the proper connectors, you may not notice an improvement at only a few feet from the aperture. Once it is working, go 100 feet away and you should see a substantial increase in the signal when pointing at the unit. stu **************************************************** Stuart Jeffery Home Office +1 650 966 8199 1072 Seena Ave Home Fax +1 408 850 1959 Los Altos, CA 94024, USA Mobile +1 650 966 8199 **************************************************** -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Tuesday, November 11, 2003 10:59 AM To: [EMAIL PROTECTED] Subject: [BAWUG] Trouble building a cantenna Hi, I am trying to build an antenna by following the directions on http://www.turnpoint.net/wireless/cantennahowto.html . I am using a Linksys WUSB11 v2.5 (the one with an MMCX connector on it). The can I am using has a diameter of 3.94 in, and the length is between 5.5 - 6.0 inches. Before I spend $20 on an N connector/pigtail and more for shipping, I want to make sure the thing works. I drilled a small hole 1.75 in from the bottom. I found some thick copper wire, and stripped the covering off of the last 1.21" part. I cut the wire to about 2" length. Next, I set up my D-Link DI-614+ router in the same room. When I remove the default Linksys antenna, I get a very poor signal-to-noise ratio on Netstumbler (as predicted). Attaching the Linksys antenna greatly improves this (as predicted). Next, I had a friend take one end of the copper wire and stick it into the internal MMCX connector on the Linksys. I held the other end 1.21" into the can. The effect of all this is that I had the copper wire sticking into the can exactly as the web site at Turnpoint describes. The can was pointed directly at the router - no more than 5 feet. The SNR I measured was not much better than with no antenna at all. No amount of wiggling, etc. of the copper wire could rectify this. Obviously if this thing can be made to work I will spend the money on the pigtail/N connector, but I will feel very stupid if I spend $30 on these two things if the entire setup doesn't work. My questions are: 1. The inside of the can is coated with some kind of white lining - could this be the problem? Scratching this off with my key reveals a silver metallic can (predictably). 2. The length of copper wire outside the can which extends to the MMCX connector is only about 1". This shouldn't make any difference - right? Or is it required to use the N connector/pigtail before the setup will even begin to work? 3. Are the Super Cantennas at www.cantenna.com any good? Are they worth the extra money when (theoritically) you can build one out of the garbage? 4. Any other ideas on why this isn't working? I've measured things like 10 times and tried to get a decent signal numerous times - all without good results. My intent (once I get the thing to work with an AP in the same room) is to reach an AP across the street. I don't think I need to amplify the signal much, because the builtin Linksys antenna seems to pick up a trace signal every few minutes. And I don't need full 11 MBPS bandwidth - just 1 or 2. Thank you! Best Regards, James Johnston E-mail: [EMAIL PROTECTED] -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
