Fascinating information on stacked antennas for a shunt fed tower but.......
in my case I lost my A4 Tribander after Hurricane Omar but the 85 foot
Rohn 45 remained intact. So I ran up a 35 foot aluminum stinger on the
top and retuned everything. It worked as expect although not quite a
1/4 wave. This year I got up at the 87 foot level a 4 element modified
A-4 on a longer boom of 35 feet. From what I have able to determine
with the new retuning of the cage feed is that the stinger is no longer
visible at RF. I determined, correct me if I am wrong, that since the
resonant frequency decreased and the base impedance impedance increased
on my MFJ-259B that the stinger had vanished because of the large yagi
below it.... I wonder if anyone has checked this out with EZNEC that
the only plausible reason for a stinger above a large yagi below is for
a longer lightning rod at the top of the tower.
I think a good rule to apply is that 1/4 physical height on 160 is not
required for a 75-90 foot tower with a large yagi on top. But this may
be wishful thinking but I would like to think it is true. Mostly likely
the same principle applies to Marconi "T"s with at least 75 foot
vertical drop and enough balanced horizontal to make the antenna appear
to be a 1/4 wave at RF and you have a great TB antenna assuming
reasonable amounts of radials.
Any thoughts?
Herb Schoenbohm, KV4FZ
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160 meters is a serious band, it should be treated with respect. - TF4M
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