[TowerTalk] Super high antennas on 10 to 20

[n4kg@juno.com]

N4KG answer below.

On Fri, 1 Feb 2002 Michael Watts <wy6k@yahoo.com> writes:
> 
> So has anyone tried using an elevation rotor on a high yagi?  Why 
> couldn't  you have the best of all worlds with a high yagi and point it
up 
> for high  arrival angles?
> 
> Michael WY6K
> 

That's one of those 'good ideas that didn't work'

The problem with tilting is that while you may get 
a slight increase in gain on the incident wave, you
get a LARGER  DECREASE in the ground reflection
which results in LESS combined signal at the desired 
angle. 

To view this phenomenon, plot the free space pattern of the antenna
and then image rotating it up or down.  Notice that the change from
the desired angle to the center is rather small and slow, whereas
the change going away from the same desired angle is much larger.

Maximum combined radiation at any angle 
(incident wave plus ground reflection)
occurs with the boom level, assuming level ground.

Tom  N4KG


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