I have a 73.5-ft. wire vertical over a decent field of radials (about 60 or
so, 50 to 120 ft. long).
I have configured this vertical two ways over the past several years and am
wondering if they are equal enough in radiated power that I should just use
the simpler of the two.
The configurations differ only in the topload "T", and the feedpoint
matching.
Configuration 1: 70-ft. flat horizontal topload wire with vertical
attached at center. Feedpoint is 25+j0. Matching is through a 2:1 UNUN
wound as per Sevick on a FT-150K.
Configuration 2: 186-ft. flat horizontal topload wire folded back on itself
to fit in a 60 x 6-ft space. (From the center vertical attachment point,
each topload leg goes out 30 feet, turns 90 degrees for 3 feet, then turns
back on itself another 90 degrees and goes 60 feet. Looks like a
squared-off "S".) This resonates the antenna below 1.8Mhz with a feedpoint
Z of 37 +j245. Matching is through an L-network. My intention was to
increase radiation resistance and efficiency and move the current maxima
away from the feedpoint and to the center of the vertical for lower takeoff
angle.
My question is how much am I losing in each system. Is the UNUN
more/less/same loss as the L-network?
I run 1200 watts and the L-net components are sized adequately. A 1-minute
keydown produces no arcing, and the coil and cap do not get hot.
Thanks,
Steve KK7UV
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