At 10:15 18/01/01 -0000, G3KEV wrote:
...
The antenna loading coil is an integeral part of the actual antenna system
and needs to be placed UNCAGED under the antenna vertical for maximum
efficiency.
As I said before the loading coil unshielded at the base of a short vertical
also contributes to the radiating efficiency
...
The radiation resistance of a multiturn loop is :
Rs = 31200 x (n x F / L^2)^2
where Rs = radiation resistance, n = number of turns, F = loop area, L =
wavelength.
For my loadingcoil n = 120 and F = 0.04m^2, so at a wavelength of 2200m the
radiation resistance will be about 30 nano-Ohm. Estimated radiation
resistance of my inverted-L antenna is about 40 milli-Ohm.
Shielding the coil (done properly - avoiding short circuit turns) would
make my signal 0.000003dB weaker.
73, Rik ON7YD
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