> 2) Inverted L with loading coil at the top of the 30-foot vertical
> section.
>
> 3) Linear-loaded 30-foot vertical.
>
> 4) 30-foot whip center-loaded with coil.
Actually a linear loaded antenna (assuming a helical wire the whole
length) has about the same radiation resistance as somewhere between
base and center loading. It ranks in somewhere that area for
radiation resistance.
The main problem with helical wound antennas is they have very very
poor form factors in the "loading inductor" and so are VERY lossy
compared to a good lumped coil system (even when base loaded).
You can see this effect in mobile antenna shootouts, where linear
wound mobile antennas consistently rank at the bottom of
pile...almost always far below base loaded antennas.
With that in mind, I'd rate a linear loaded (helical loading) antenna
dead last.
73, Tom W8JI
W8JI@contesting.com
|