Ken,
What you say is true, and you can point out some good examples of antennas
that are not resonant that work better, and extended double zepp, for
example. But you have to qualify what you say. You need a low loss feed
line, like a open wire feed line for example. Then you need a low loss
antenna tuner, and you have to use it right. I have seen antenna tuners
with a 3 dB loss. If you use a balun with an antenna tuner, it needs to be
high efficiency too. For our last field day, we used a tri band beam, a 40
meter wire beam and a 135' Windom with a high efficiency balun at the top
and fed with coax, which was broad band across 80, 40, 20 and 10. Nary an
antenna tuner in sight.
W1CG
At 06:01 PM 9/4/2004, you wrote:
This is not a Ten-Tec specific topic, however.....
And, of course, he/she needs to know how to change bands and load the
antennas (which ought to be resonant).
While there may be some reasons that it is "nice" or "convenient" to have
antennas resonant, it is absolutely not necessary. I does not even make
them work better in some instances, or significantly better in most
instances. Yes, the transmitter should have a load which is not too far
from being the right impedance and low reactance (50 ohms for most rigs
these days) This can be accomplished using a tuner, making the antenna
system (antenna, feedline and tuner) not necessarily the antenna by
itself, resonant. Or it can be accomplished by using a wideband antenna,
such as a discone or log periodic, that has such a broad flat impedance
curve that it can hardly be called "resonant" at all. A lossy antenna ar a
dummy load is another way, but of course not the best.
Ken N6KB
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