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JIMMIE · November 27th 06, 12:23 AM posted to rec.radio.amateur.antenna

wrote:
ml wrote:
hi

I was wondering, if i designed a horizontal center fed dipole... w/a
sorta fan say a few legs for 10-40m... but

instead of just attaching coax, i attached a sgc tuner at the feed point

would i expect the dipole to resonate"" as one would predict if feed
directly via coax ex the 40m leg resonates on 40 or would the tuner
'grab' different ....??

tnx

naturally a single wire could be tune very well w/the remote sgc but
i ponder

If you were using the fan dipole with a tuner attached to the feed
point, the tuner would try to establish the best 50 ohm match from the
coax to the complex impedance presented by the antenna. The frequency
at which you are trying to tune, and the complex impedance of the fan
dipole at that frequency, will determine whether the tuner can match
the coax to the antenna. One particular wire of the fan could
dominate, but the tuner will try to match the overall impedance.

Gary N4AST

I have some experience with an arrangement like this using a different
auto-tuner. Four different freqencies were suppose to be covered that
were harmonically related. The antenna was cut to resonate as a 1/4 wl
antenna on the greatest frequency. As one would expect the tuner had
problems matching when the antenna was an even number of 1/4
wavelengths long. The immediate solution was to add more wires that
were shorter than the origonal by 1/2 and 1/4. With this arrangement
the tuner had no problem loading into the antenna. Probably the
simplest solution would be to select a wire length that is not resonant
on any of the desired frequencies so the tuner would not be trying to
endfed an I(1/2) wl antenna at any used frequency. Of course using the
single wire could also be a problem because at the highest operating
frequency it could be 1wl long or longer and exhbit an undesirable
radiation pattern.

Jimmie D