On Wed, 16 Apr 2003, John Geiger wrote:
> I have an antenna question for the reflector. On the
> local repeater here, the general consensus is "Get a
> horizontal loop for VHF, they will outperform yagis".
> (I know better, but hey, I just report what I hear).
> So here is my question-I have heard gain figures
> attributed to loops, or to stacked loops, but I don't
> understand how. If an antenna is truely
> omnidirectional, where does the gain come from?
>
The loop antenna is not truly omnidirectional - it is
omnidirectinal in the horizontal plane but not in the vertical
plane. It radiates power at angles above and below horizontal in certain
patterns. When you phase/stack two or more properly, less power goes
above and below the horizontal plane and more goes into the horizontal
plane, hence more gain to the horizon.
A Yagi still has more gain, but it's directional.
73, Zack W9SZ
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