04-27-2005, 05:22 PM
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Join Date: Apr 2005
Have you made the Chaparral feed?
I earlier made one of these stand alone "cantennas", D 100mm with a 31mm probe positioned 44mm from the back wall. It is working just fine as a standalone antenna. www.saunalahti.fi/elepal/antenna2.html
Currently I'm experimenting with a 60 offset dish to establish a long distance 2,4 GHz WLAN connection.
When attaching my cantenna to the focal point of a 65cm offset satellite dish the received signal strength is increased remarkably as expected, but during the actual WLAN traffic the received packets dropped almost to zero. Throughput of the link went down. Maybe it's because of poor SWR of the combined system, or my can is not illuminating the dish as a proper feed horn. www.smw.se/qa/qa10.htm
So, now I'm thinking to redo the whole feed and add a scalar ring around the feed to better illuminate the offset.
What would be the optimum length / diameter of the feed and how is itís diameter related to the scalar rings and general how to properly illuminate an offset dish?
Best regards, Christer
| Originally posted by johnburns@Nov 18 2003, 10:47 AM |
I am going to attempt to correct this problem by using a Chaparral feed. This is basically a ring around the cantenna which affects the transmission angle - in my case, will increase the angle so that as much of the dish as possible (without transmitting around the sides of it) is fed with the signal.
I have cut my 'liquorice' can down to 181mm long which is apparently close to the optimal length - not sure why as it shoudl be an odd number of 1/4 waves long, but I'll try anything to get these dishes working..after all, the dishes were free and I'm having fun working it all out......
Will report back soon, In the meantime I need to go can shopping again for a 127mm diamtere can (at least 40mm high) - any ideas?
More information on chaparral feeds is available from http://www.qsl.net/ki7cx/wgfeed.htm