G'day gang,
It is seems to be generally acknowledged in the radio books that I have
that the limit to sloping a vertically polarised antenna such as a delta
loop or a ground plane to the vertical before its performance is seriously
affected is about 30 degrees.
However, much of my book collection predates the use of EZNEC/ELNEC antenna
modelling software and I am wondering if in fact the slope can be somewhat
greater (say 40 degrees, or even 45 degrees) before performance, in terms
of a radiation pattern of low angle vertically polarised radiation, is
affected.
Perhaps some of those who have EZNEC/ELNEC (and perhaps even used antennas
with 40/45 degrees slopes) could comment.
Like a number of topbanders on this reflector, my wire antennas for the
band run above a HF triband yagi, necessitating a slope on them. If I run
an inverted-L antenna of 66' up, 66' out, I can fit this under the
tribander. On the other hand, if I run the 'vertical' part at around 40
degrees (over the top of the tribander), I can put up an inverted-L with a
95' up, 37' out.
To me the latter sounds a much more promising idea, but I would be
interested in some feedback/opinions.
Vy 73,
Steve, VK6VZ
--
FAQ on WWW: http://www.contesting.com/FAQ/topband
Submissions: topband@contesting.com
Administrative requests: topband-REQUEST@contesting.com
Problems: owner-topband@contesting.com
|