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Use a Surplus Primestar Dish as an IEEE 802.11 Wireless Networking Antenna



Use a Surplus Primestar Dish as an IEEE 802.11 Wireless Networking Antenna
The resulting antenna has about 22 db of gain, and is fed with 50 ohm coaxial cable. Usually LMR400 or 9913 low loss cable is used if the source is more than a few feet from the antenna. The range using two of these antennas with a line of sight path is around 10 miles at full bandwidth.

Things You Will Need:

A Primestar dish. (You may use any old dish, but if it is bigger than the Primestar the gain will be higher, and it may not be within the Federal Communications Commission rules for use within the United States. In fact I have come to find out that there seem to be several different dishes that Primestar used, and I am only sure that the one I used, pictured above, used with the ordinary Wavelan or Airport transceiver card is within the effective radiated power limits given by the FCC.) 
A juice can (about 4 inches in diameter and at least 8 inches long). 
A chassis mount N connector. 
You will also need a "pigtail" connector which has the proprietary Lucent connector (for the PCMCIA card) on one end and an N connector on the other. The pigtail can be obtained from a number of online stores for $35 to $40.

Construction Steps:

After deciding on a place to mount your antenna (which hopefully has a line of sight path to the access point or other IEEE 802.11 site), remove the apparatus at the feed position of the dish, saving the mounting hardware. 
Using a can opener, cut one end of the juice can out, drink the juice and wash it out 
Solder a quarter wavelength (1.15 inches) of wire onto the center conductor of the chassis mount N connector. 
Using a punch or whatever other tools you deem necessary, mount the N connector so that it is about 1.2 inches from the closed end of the juice can as shown below. It is also a good idea to put a drip hole at the lowest point of the can to insure that water doesn't build up inside. After having this up a for a few months, I think it would be nice to put a plastic lid on the open end of the can so that the inside doesn't rust. During the time mine has been up, it has rusted and I have lost a couple of db on the signal strength. These two things may be correlated. 
If you are certain of the polarization you will need, mount the juice can so that that polarization is achieved. (You want the antenna you are communicating with to be lined up with yours.) If you don't know the polarization you can set everything up and before mounting the juice can, experiment to get the maximum signal strength by rotating the juice can around its axis. Most commercial antennas I've seen are using vertical polarization, so that the picture below shows you the proper orientation. You want to mount the juice can so that the opening is just at the focus of the dish. In my installation I didn't quite achieve this, but I only lost a db or two by taking the easy route. I still have about 25 db signal to noise ratio, so this wasn't important to me. The easy route is to mount the can as far back as you can along the mount, by punching two holes through the can and bolting it in. The perfectionist's method would be to find the best feed place (which I found to be just a little farther back) and use some PVC tubing or something to extend the mount so the feed is in the perfect position. In some installations, every decibel will count and this should be considered.
Authored by Rob Frohne at Homepage, Added: 16 Apr 2006



http://www.wwc.edu/~frohro/Airport/Primestar/Primestar.html

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