[TowerTalk] measuring beam forward gain

[Richard (Rick) Karlquist]

Al Williams wrote:
> What errors may be caused by:
> 
> The signal generator being too close (or too far away) --how far away is ok?
> The signal generator being too low in height?
> 
> Although antenna modeling programs will display a 3d gain pattern, it seems 
> difficult to me to quantify the gain.  Thus one uses an azimuth gain pattern 
> for specific elevation angles. Can the rotational gain difference change for 
> different elevation angles?
> 
> k7puc

I only use these measurements to measure relative gain between
two different antenna configurations.  Measuring absolute gain
is a whole nuther ball of wax.  For my measurements, I put the
sig gen 1000 feet away.  That is many wavelengths, even on 40 meters.
It is 30 feet high, which is adequate, even on 40 meters.
I suspect you could get away with much less distance and height,
but I haven't tried it.  I feel confident that whatever maximizes
the gain on the range will maximize gain at all useful takeoff
angles during actual use.

Rick N6RK