--- In Repeater-Builder@yahoogroups.com, "Jeff DePolo" <j...@...> wrote: >
> Their sample pattern when side-mounted on a tower shows 9 dBd forward gain > and -2 dBd off the back away from the tower, again with all elements in a > line. That may be getting closer to being realistic. > Several years ago I ran a real-world test using our repeater as an RF source. I could remotely switch between a top-mounted DB224 in the omni configuration, and an Antenna Specialists ASP601, which is basically the same antenna made by another manufacturer. The A/S antenna had it's dipoles directly mounted to one leg of the tower, which is about 15 in. between legs, and all in line. It was mounted 40 ft. lower on a 180 ft. tower, so it will naturally show about, I think, 2db lower field strength at many miles away because it is lower. Using the top antenna as 0db reference, I put on many miles and took numerous measurements at pretty much random locations at distances of 5-25 miles using my step attenuator. In the favored direction, the A/S showed 2-3db gain over the top antenna. At 90 degrees either side, it was down perhaps 2db. Off the back it was 9-10db down. Was it scientific? No. Was it useful and interesting? Yes. Laryn K8TVZ
