On Fri,9/23/2016 11:15 AM, RT Clay wrote:
In my opinion, if you are height limited, you want to stay away from elevated
radials. If you elevate your radials, you are giving up valuable vertical
distance which will further lower the feedpoint Z and increase ground losses.
Excellent post, Tor. I'm not so sure that I agree with this paragraph
though. While elevating radials DOES reduce the effective height of the
radiator, and thus radiation resistance, elevating radials reduces
ground losses for the same number of radials. In essence, efficiency is
the voltage divider ratio between Rr and Rg + Rr, where Rr is the
radiation resistance and Rg is the ground loss. So it can be a tradeoff,
depending on what's practical at your QTH and how good your soil is.
Based on my 160M experience (4 radials up about 20 ft on a full size
vertical), I'd guess that 8 ft is pretty good for 80M. Those 4 radials
at 6 ft had way too much ground loss. On advice from N6BT, raising them
to 20 ft helped a lot. The feedpoint for those verticals is about 2-3 ft
high, and the radials rise quickly as they go away from the feedpoint in
a "gull wing" configuration.
73, Jim K9YC
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|