This idea was in a ham magazine years ago, to solve a similar problem. It was on a very large tower, with a large face. This particular application used three sets of phased beams (two at each leg, fired tangentially to the tower). You have to start out with a bunch of gain at each leg, not just a dB224 or such. He used 2 five or so element beams on each leg. He fed them with a three way power divider made out of copper pipe to get the proper impedances. I wish I knew where the article was. I am thinking it was not in QST but maybe one of the ham technical mags that is still no longer around. I would search Google just in case a similar application is documented. He said it worked OK and gave him a somewhat circular pattern, albeit no more than 3-4 dB.
Now that I think about it, with all the wireless stuff (cell antennas) that I have seen mounted around a water tower single legs (the modern towers), on buildings at each face, etc. , I bet there is info out there that you can tailor for your needs using the phased antenna approach. Roger W5RD ----- Original Message ----- From: tony dinkel To: Repeater-Builder@yahoogroups.com Sent: Saturday, January 27, 2007 12:45 PM Subject: [Repeater-Builder] Re: Antenna on the side of a water tower I don't think you are going to be able to model it to your satisfaction with any software you or I could afford. Perhaps you need to adopt an empirical approach, put up an antenna and see what you get. Drive test it, take field strength readings, plot and graph the real world data as much as you want. Then you can add in small tweaks in spacing, heading and gain. I would suggest starting with a low gain antenna, like maybe a 4 bay folded dipole array at the easiest to mount spacing from the tank. After you tweak that in for a while and have a feel for how it works, perhaps you could add a second antenna exactly 180 degrees on the other side of the tank. Try 0, 90, 180, 270 or totally random phase angles between the two antennas. Don't get bogged down in the math. Have fun with it. Last time I checked, ham radio is still a hobby. td, empiricist wb6mie >It's hard to put into text. > >What I'd like to do, is get back to the more omni pattern if at all >possible. The way everything is situated, if I put the antenna on the >side of the tower facing through most of our coverage area, I think it >will end up with too much gain in that direction, twoard another >repeater to the northeast. > >Mostly, I'm just looking for a way to model what happens, ideally in >something that radio mobile can digest, and I'll work it out from there. > > __________________________________________________________ Search for grocery stores. Find gratitude. Turn a simple search into something more. http://click4thecause.live.com/search/charity/default.aspx?source=hmemtagline_gratitude&FORM=WLMTAG
