Rag,
We had QSO in Winter of 2007 and obviously conditions were quite good at
solar minimum. In our qso I was running 100W and using a 3 element
end-fire array which is of parasitic origin. I have several hundred EU
QSOs in the log at 100W power level from my AZ QTH.
There is no need for fancy phasing networks, matching networks,
combiners/circulators and dummy loads for reflected energy. N6RK and
K3LR are correct. The parasitic arrays may not have the ultimate front
to back ratio without careful tuning however their real world
performance in gain is within a few tenths of a db of theoretical and
can be done with considerably shorter elements provided the antenna is
top loaded by wire , either in a "T" or "V" configuration, the driven
element is matched by a low loss un-un transformer, base loaded tuning
coil losses are kept to a minimum by using silver plated or large
diameter copper tubing and finally by putting a major effort into the
ground system with 64 or more radials under each element. Spacing is not
a major factor, however I would keep spacing near 1/4 wave to minimize
dramatic impedance swings on the driven element, especially in the case
of going single element OMNI mode. I have measured individual element
currents and found them to be very much so in the area of expected values.
With old Sol coming back to life it will take some major effort in
antenna work to get the desired results. The parasitc arrays provide a
way to be cost and performance effective.
73
Bob, W7RH
--
Bob Kile, W7RH
DM35OS
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“There are three kinds of men. The one that learns by reading.
The few who learn by observation.
The rest of them have to pee on the electric fence for themselves.”
Will Rogers
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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