[TowerTalk] 160 M OCF antenna
n6ry at arrl.net
Sat Feb 25 18:29:04 EST 2006
At 11:44 AM 2006-02-25, David J. Ring, Jr. wrote:
>One trick that I've used to benefit when I couldn't put up such an antenna
>(extended 1/4 wave inverted L) and could only fit a 1/4 wave length of wire,
>was to use "twin lead" or TV line. You feed one wire at the beginning, then
>short both wires at the far end, and the remaining wire at the beginning
>gets connected to ground. This arrangement doubles the radiation resistance
>and consequently halves the ground losses of the antenna.
Using a folded monopole will indeed raise the feedpoint impedance (by
a factor of 4, which can make matching easier), but the radiation
resistance and ground losses are unchanged, since the net current
flowing into the ground is the same regardless of the number of conductors.
See http://www.w8ji.com/radiation_resistance.htm for a good
explanation of this.
73, Terry N6RY
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