Topband: Sloping verticals

[Steve Ireland]

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
  


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