468 / Frequency (MHz) should get you close, however your tower is really too
short for a sloper. Why not just put up and inverted V? You can use your TX
SWR meter to tune the antenna. Adding a beam later shouldn't have much effect.
Subject: [TowerTalk] Length of Sloper?
Date: Wed, 29 Dec 2010 18:59:01 EST
I'm installing an 80-meter Sloper on a self-supporting 60' tower. (no
guys) I don't have a MFJ-259 or other antenna bridge with me so I'd
appreciate your thoughts to help get me in the ballpark. The 80-meter Sloper
attach to the tower at the 55' level. Currently there are no other antennas
on the 60' tower. A couple questions:
1) With no other antennas on the 60' tower, do you think the length of the
Sloper wire will be close to the formula 234/freq? Or do you think the
Sloper will wind up needing to be longer or shorter than 234/freq?
2) The once I get the Sloper tuned for minimum SWR on 80-meters, if I later
add a Tribander to the top of the tower I'll no doubt need to re-tune the
Sloper, but do you think the Sloper will need to be shortened or
lengthened after the Yagi is added?
Thanks & 73,
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