On Sat,12/5/2015 2:43 PM, Mark Lunday wrote:
I have learned from the wise
old-timers on this message board that a vertical antenna with broad-banded
behavior is a lossy antenna. Same with a vertical antenna that shows 1:1
match.
Horse-pucky on both counts. I've been reading this message board for ten
years, and most guys here are a LOT smarter than that.
There are several ways to broadband an antenna. One is to increase the
conductor diameter. A vertical made from Rohn 25 will have greater SWR
bandwidth than one made from a single #14 copper wire (or even a single
#10 wire). It is well known that the SWR bandwidth of a wire vertical
can increased by building it from two widely spaced conductors that are
tied together top and bottom. Both ways of doing it will yield an
antenna that is physically shorter to achieve resonance.
Likewise, there are multiple ways to achieve a 1:1 match. Yes, a
vertical with a poor radial or counterpoise will show a match closer to
1:1 because of ground losses. BUT -- a vertical with a very good radial
or counterpoise system, which has a feedpoint Z near 30 ohms, can be
matched to 50 ohms in several ways that do not increase loss. One is
with an autoformer. Another is with a simple matching network. Another
is to tune the antenna long by adding top-loading, which increases the
feedpoint Z to 50 + jX ohms, then add series C at the feedpoint to tune
out jX. ALL of these methods yield 1:1 SWR with high efficiency.
73, Jim K9YC
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