MaxTech (Zcomax) had diagrams on their website of how to do this with their yagi's a while back. If done perfectly, it can work out OK, but these are the warnings that the MaxTech tech warned me about when I asked a few years back....
The gain may be less than you think - two 15 db antennas does not equal 30, it equals 18 db. Doubling the gain only adds 3db. Of course, 3db can still be significant, but it's less gain than you'll have with most grids. As well, you'll pollute the surrounding air less with a more directional antenna so going to a grid may be better, simpler & cheaper. Also, if you don't have your antennas in perfect 'phase', the waves collected by each may actually cancel each other out more than they benefit each other. You'll have to have the EXACT same length of cables running from each antenna. If 1 is even a few CM longer, then the path length will be longer and you'll get the peaks and troughs of the waves cancelling each other out. As well, if you are wiring two together with a splitter/combiner, with the extra connectors and stuff, you may be loosing half of the 3 db gained anyway. - Todd Chamberlain ----- Original Message ----- From: "Jeff Vannest" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, February 05, 2003 10:11 AM Subject: [BAWUG] Wiring yagis together > Hello everyone! > I apologize for making my first post a request for help...seems kinda > lame to me. But I'll stick around for a while and try to help others if > I can. > > Is it possible to wire 2 yagis together? > > Some friends and I have built a wireless network in our neighborhood. > The general idea can be found at > http://www.jeffvannest.com/pictures/pictures_db_cache/Neighborhood%20WAN > .jpg > > Currently, the antennas we're using are different than the graphic > describes. The multipoint bridge uses a 5.2dBi Cisco (Cushcraft) Omni, > but the other 2 antennas are a ~13.5dBi homemade yagi > (http://www.cawnet.org/antenna/) and a 19dBi Hyperlink reflector grid > (http://www.hyperlinktech.com/web/hg2419g.php). > > Houses are max 800ft apart, where the multipoint bridge is in the > center, and the other 2 homes are about 60 degrees apart. According to > specs, we should be running *well* within specs for this hardware, but I > think we're having an interference problem, since even my 2.4Ghz office > phone can cause the bridged locations to loose significant packets. > > So we're wondering is if it's possible to build 2 more 13.5dBi yagis and > wire them together (each pointing at a client bridge antenna) as a > replacement for the 5.2 omni. We're using a WAP11, so we could put a > yagi on each antenna post, but I understand that's not quite proper for > our implementation. > > Our biggest problem is that I can't find instructions on how to build a > simple antenna with a 60 degree beam width, and I can't afford a > commercial one! > > Thanks for your thoughts!! > Jeff Vannest > > > -- > 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
