On Sun, 13 Jul 2008 00:04:55 GMT, "Dave" wrote:


"John Ferrell" wrote in message
.. .
Why do we always mount our HF Yagi's in the horizontal plane?
Antenna maintenance would be much easier for those of us with tilt
over towers if the antenna were in the horizontal plane when down for
maintenance!

John Ferrell W8CCW

vertical yagi's work fine...
....

No.

Look at the horizontal and vertical diagrams of a Yagi.
(Talking about a single Yagi, not stacked)

The narrowing of the beam characteristic is only dominant
in the horizontal orientation, the vertical retains about the
characteristic of a single dipole.

So if you tilt a yagi to vertical, it will receive from all
directions, especially the EMF noise in your vicinity.

When horizontally mounted, it will receive of course from
above ( the sky) and from the bottom below your tower
but generally there is less interference than in the whole
360 degrees around you.

Repeat: the vertical yagi diagram is not much better than
that of a single dipole, regardless how many horizontal elements
you add in length of the beam. Try it out of you don't believe,
but listen to the noise you get, not the signals.
Only stacking of yagis can improve the situation.

w.