04/14/98 09:10 AM
If you haven't seen the article in March 98 CQ Contest Magazine, I think it
would be of interest for those wanting to design a vertical yagi.
One of the key influences on a vertical yagi is the height above ground.
The way the vertical elements interact with ground is of key consideration,
as they (verticals) want to be mounted close to the ground (fractions of a
wavelength) to give you the best performance. Once you get above a few
feet from ground, the one nice fat low-angle lobe starts to split into many
smaller lobes, and a large high angle component starts to form.
Then there is the mechanical aspect of having a non-conductive mast support
the yagi so the pattern is not interfered with. You could put a
non-conductive insulator in the mast to break it up - which, if planned
correctly, would provide a non-resonant support which would not be part of
the circuit. But the insulator would introduce a mechanical weakness in
73, Kenny K2KW
FAQ on WWW: http://www.contesting.com/antennaware-faq.html
Administrative requests: antennaware-REQUEST@contesting.com