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5/4 Wave Two Meter Antenna
Electrically, my design is pretty much the same as the original, except I epoxied a chassis mounted SO-239 to the end of the PVC and fed the antenna from that point. I also used a much thicker radiating element (#12 vs #18). This lowered the resonant frequency a bit, forcing me to shorten the length to get it back into the center of the ham bands. To tweak this antenna, you will need to adjust both the length of the main element (60-1/2"), as well as the matching section (15-1/8"). The former is not all that critical, and you can just fold over the end 1/2" at a time to adjust the length for testing purposes. The matching section is another matter. During tests, I found out the hard way that a 1/4" change could make the difference between a good or bad SWR. Cut carefully if you attempt to optimize this antenna! |