As far as phasing the antennas around the tower, it can't be done. Well it can but you will end up with more nulls and a worse pattern than you started with.
The problem is that most signals will arrive at more than one antenna. Because they are different distances apart to the mobile there will be a time difference between the two. So you say ok, I will just make the phasing harness that same length as the antennas are apart. That would work great for one specific direction. But what happens when that mobile moves to a new azimuth location? Then there will not be the same distance to him between the two antennas as there was when you made the phasing harness. Now you have a new time difference between arriving signals but you have the same length phasing lines. The result is that the combined signals are no longer in phase so you have less gain. If the two signals fall out of phase then they will cancel. You have a big null in the pattern there. 73 Gary K4FMX > -----Original Message----- > From: [email protected] [mailto:Repeater- > [email protected]] On Behalf Of afa5tp > Sent: Wednesday, March 10, 2010 12:31 PM > To: [email protected] > Subject: [Repeater-Builder] Antenna Phasing Question > > Hello Folks > > I have three (3) Antel [BCD 80010] 806-900 mHz vertical antennae that I > would like to mount on the three legs of my tower for omni pattern (Rec. > only). Several questions come to mind. > > 1.) At the rated frequency, how many inches should the side arm place > the ant. from the tower? > > 2.)What would be the best way to phase the antennae? I have a Andrews > three port "Splitter", and will use "LDF4-50A for feedline. I would > suspect the length of the pigtail from each antenna to splitter is going > to be critical.......or not, for receive only? > > BTW......How good of an antenna is the "Antel" BCD 80010? > > Many thanks for any guidance and wisdom. > > Tim Hardy > W7TRH/AFA0TP > Vashon Is. Wa. > > > > ------------------------------------ > > > > Yahoo! Groups Links > > >
