TopBand: good commercial 160 ant?
Earl W Cunningham
Tue, 28 Jul 1998 11:37:50 EDT
Modeling software shows that a 45-foot vertical with four "radials" each
41 feet long connected at the top and extended horizontally will resonate
at 1830 kHz. The feedpoint resistance will be about 10.25 ohms, so a 1:4
unun will give a close match to 50-ohm coax.
If the top-loading "radials" slope downward, their length will have to
be longer appropriately -- a 45-degree slope requires about 47-foot
IMHO, this vertical would be more efficient than an inductively-loaded
If you have the room to go 90 feet horizontally from the top of the
vertical, such an inverted-L is the easiest way to go. It would resonate
at 1830 kHz and Its feedpoint resistance would be about 11.5 ohms, so the
1:4 unun would again be appropriate.
The pattern of the vertical with four top-loading wires is circular. For
the inverted-L, the pattern favors the direction opposite to the
direction of the horizontal wire, with about 1 dB gain, and a 2 dB F/B
All modeling was done using #14 wire for all parts of the antennas.
As with any vertical, a good ground radial system is essential.
73, de Earl, K6SE
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