Just so we're singing from the same page, a few comments first. Pointing the dipoles all in one direction, for instance, increases the gain of a DB224 from 6dbd to 9dbd in the favored direction. And off the *back*, there is still a gain of 3dbd. It has a front-to-back ratio of 6db. Useful, but not really a "beam". The -3db beamwidth of the front lobe of this "beam" is somewhere near 180 degrees. So the point is that aiming any one, or several, dipoles toward openings between buildings is probably not going to help huge amounts.
Taking your idea a step further, it would be interesting how 3 real beams, fed with a power splitter, would work in this case. Back to the DB224 antennas, the RF lobe maximums aren't always in the direction that the dipoles are facing. As described by an engineer at DB Products, if you point 2 dipoles north, and the other 2 dipoles south, you will end up with a pattern favoring east and west with .75db more gain in those directions than the omni configuration. Must be because east and west both "see" all four dipoles... Fun, huh? Laryn K8TVZ --- In Repeater-Builder@yahoogroups.com, "dallasreact112" <[EMAIL PROTECTED]> wrote: > > I have a question about the DB base antennas such as the DB-224, DB- > 420, etc. As most of you know they consist of folded dipole "trombones" > mounted on the mast at 90 degree angles with a phasing harness to > create a omnidirectional pattern. I have heard of pointing the > trombones all in one direction to create a "beam". My question is has > anyone pointed them in other directions? What I'd like to do is point > mine in roughly 120 degree slots, to go around downtown bulidings which > block the RF path due north, SW and E as we are located on a 40 story > builing in the middle of downtown which has taller buildings blocking > the aforementioned directions. Essentially what I want to do is "beam" > the signal in to the open "slots". > > 73 and Thanks, > > Bernie Parker > > K5BP >
