[VHFcontesting] Gain from an omnidirectional antenna

[Zack Widup]

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