[amsat-bb] (no subject)
N2OEQ at aceweb.com
Sun Mar 11 20:28:42 PST 2007
I noticed some spots about satellite beams for fm birds.
After 2 years of trying different anrtennas etc, I now have my ideal setup. I tried 3 different homebrew beams. I learned that for a fixed elevation on azimuth rotator, the optimum beam was 7 elements at 10 degrees elevation with a DELTA match on the driven element.
I have great reception using a hamtronics preamp (lnk-450) on the shack end of a 15 foot run of 9913 coax. The reception is good to great from just a few degrees above the horizon up to the zenith or overhead.
I tried 8 elements with a gamma match but was too sharp with little overhead gain.
I tried a 7x7 cross yagi fixed at 20 dgrees with minimal success. The horizontally polarized 7 element delta match outperforms it vastly.
I'm guessing the delta match helps with the higher angles. ( Delta match looks like a triangle at the center of the driven element.)
Consult the antenna book by ARRL or search for information.
Photo of antennas at: http://members.aceweb.com/n2oeq
Hope this helps someone. 73, pat
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