This is gold, Jim. Thanks much for sharing!
Kim N5OP
On 10/17/2020 5:15 PM, Jim Brown wrote:
On 10/17/2020 1:24 PM, Kim Elmore wrote:
Maybe I should have said "... making sure it has a good CM choke,"
especially since you've taught us how to make them! Even if the feed
is in the center (it could be if the transmission line is run up the
bottom half) it still won't be balanced. A CM choke is always needed.
I've become convinced that balanced antennas make analysis much
easier (even possible) but that in the real world, there aren't any.
I have no idea what the electrical length is for 6 m or even 10 m, so
the low radiation-angle assumption might be invalid on those bands.
Here are slides for a talk I gave on the Pacificon Antenna Forum
several years ago on an 80M vertical dipole for our 7QP and CQP
expeditions, based on N6BT's design ideas. Yes, it does need a serious
choke were the coax feeds up through the tubing to the feedpoint.
http://k9yc.com/80M-FDVertical.pdf
Testing it in Glen's pasture showed it to significantly outperform an
inverted Vee with the center at 46 ft, but mechanical issues with the
design caused us to abandon it after modeling and building several
alternative designs.
73, Jim K9YC
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--
Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU School of Meteorology, CCM, PP
SEL/MEL/Glider, N5OP, 2nd Class Radiotelegraph, GROL)
/"A great second violinist plays second fiddle to no one." //– Robert C.
Marsh, Chicago Sun-Times./
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