Sometimes the system has not read the physics book! I once worked with four PHD's, 3 out of four said I would never make a circuit work, one abstained. I did make it work, and it worked better than the one the PHD's came up with! They were scratching there heads! By the way, I never darkened the door of any college.
Maybe I was to stupid to know it would not work because my engineering skills were self taught and OJT, none of it in the classroom. That's how a lot of advances in today's technology based world happens, and not always from a College educated engineer. All I was saying in my original post was that you can't arbitrarily say "never" use more than a 8 dB antenna at 100 feet. Every site has to be evaluated on it's own merit and I stand by that statement! Paul -----Original Message----- From: Kevin Custer [mailto:[EMAIL PROTECTED] Sent: Tuesday, March 08, 2005 7:15 PM To: [email protected] Subject: Re: [Repeater-Builder] Inside a Flag pole Tower Joe Montierth wrote: >Dean specified 100ft AAT, which takes into account the >ground elevation, thats not very high off the ground. > >I own a 140 ft tower, with antennas that have >relatively high gains. I can sit at the bottom of the >tower (which should be the worst null) and still hear >and get into the repeater. I can move .5 mile away >with the same results. I can move 3 or 5 miles away >with the same results. > >The null zones created by high gain antennas are >usually so close to the antenna (when at 100 ft) that >it makes no difference. By the time you get into the >major lobe of the antenna, you will less than a mile >or so away from the tower; as you get further away, >you just get more and more into the beamwidth, not >less. A high gain antenna may have a pattern that is 8 >degrees, that would be 4 degrees above the horizon, >and 4 degrees below the horizon. With an antenna 100 >ft AAT, you would come into the major lobe just a >little over a quarter mile from the antenna. I think >most people would agree that if you're closer than .25 >miles to an antenna at 100 ft, you won't have a lot of >problem hearing (or getting into) the attached >repeater. > >I too, have worked in the RF field for a long time, >and seen some strange stuff. One thing I consistantly >see is that a high gain antenna will almost always >outperform a lower gain antenna at the fringes, or >near the horizon. It doesn't seem to matter if it is a >100 ft tower, or a ten thousand foot mountain. Even on >the 10,000 ft mountain it is hard to make the "nulls" >of much consequence, since they are such an angle, >reference the major lobe. This is from real-world >experience also. Pehaps the laws of physics and >trigonometry are different out east, I am only relying >on "wild west" observations. :) >Joe > > Same stuff happens out here in the east. I have had the exact same experience as suggested in the text above. Kevin Custer Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
