Done this several times. The tower will cause a shadow on bhe back side no matter how you position the dipoles. If you are wanting maximum gain in one direction away from the tower you must like up the dipoles in that direction. Moving some to the side really wont help the sides enough to tell and it will reduce the gain in the desired direction. I believe the DB products engineers know what they are talking about. For example if all dipoles are away from the tower leg in line you might get 9 db in front, 6 db to the sides and very little to the back. If you turn dipoles to each side you still get about 6 db on each side but now only 6 to the front. Dipoles are not very directional and when all are in phase together you get maximum gain in that direction. You will never get an omnidirectional pattern on a side mount nd if you need the offset patern to shift the signal in 1 major direction follow the manual directions. I have an 8 bay on the side of a tower with 36" leg spacing and it is located 16 miles away from the center of the desired coverage area. At 450' above ground it gives aprox 60 mobile miles to the front, 45 miles at 90 degrees and 25 to the rear on the 2 meter band. WB5OXQ. PS I am not old (62) but I have been a ham since 74 and have been trustee for as many as 6 repeaters at a time now thankfully only 1 ! ----- Original Message ----- From: tahrens301 To: Repeater-Builder@yahoogroups.com Sent: Tuesday, June 30, 2009 2:35 PM Subject: [Repeater-Builder] DB-224 patterns on side of tower.
Hi Folks, We are putting up the DB-224 on the side of the tower, which is one of those large 3 legged towers. (like you see at microwave & telephone sites). I have the DB-products data sheet on the 224, and it has some plots for side mounting on the tower. The plot in question is the 224E (all in line, pointed away from the tower). According to DBprod, it would give the appropriate pattern for our desired area. However, one of the old salts here (who has final say-so) says that you really have to put some left and right angulation on the elements to get that pattern. I guess the real question is how positioning on the side of the large tower affects the pattern - if the elements are directly perpendicular to the tower leg, versus having some rotation on the leg. I'm thinking that we will probably just have to experiment with what we get per old-salt's method & see how it works. Anybody have any other ideas? Thanks, Tim W5FN
