Over the years we have employed different philosophies on mounting sectors to towers. Our reference point was the Moto 100 series connectorized radios with sectors. We started out with 18" standoffs on a Rohn 25G tower, because some "smart guy" suggested that was what we needed. Another smart guy suggested 24", so some of them were done like that. Then, someone else suggested that we really didn't need standoffs at all, that they could be mounted each on a leg of the tower and we would be fine. (we always ran 3 120 sector/AP configuration per tower in 2.4 Ghz). As far as difference that we could measure, we found no difference in AP to SM performance when we measured at any distance of connection. Maybe we were missing something, but anyway, we settled on mounting them directly on the tower leg.
Moving forward to today. We have been installing the ePMP 2.4 series instead of 100 series 2.4s. The installation techs mounted them back to back, with North/South on one frequency (Front/Back Frequency Reuse configuration) and East/West on the other frequency. One of the 4 sectors had to have a custom mounting bar made to replace the short stubby one that comes with the sector, thus allowing the 2 sectors (North and East at 90 degree offset) to be put on one leg right near each other. Again, this is Frequency Re-use a bit of a different scenario. Anyway, today in working with Cambium, they told us we need to have at least 3 ft of vertical separation between each radio on the same frequency, so North and East could be at one level (dif. Frequencies) and South and West would be vertically separated. Alrighty then :) ..... so we have 6 towers to go move things around on. We are going to some test tomorrow on the first tower to see exactly how much separation yields us how much F/B isolation. Using ePMP eDetect feature, that should be pretty easy to see. OK....so here is where I want opinions. Really I'd like "expert advice", but I will settle for opinions :) How far "should" these sectors be "stood off" from the tower, if at all? I am not expecting to be able to measure any difference with the F/B ratio data, so its back to this is "all theory". Is the standoff question a front to back issue at all, or a "we want the metal" sector away from the metal tower a little bit? Paul Paul McCall, Pres. PDMNet / Florida Broadband 658 Old Dixie Highway Vero Beach, FL 32962 772-564-6800 office 772-473-0352 cell www.pdmnet.com<http://www.pdmnet.com/> pa...@pdmnet.net<mailto:pa...@pdmnet.net>
