Mike, a simple L network will match a huge range of impedances. If you can
characterize the R +-j at the end of your gamma no doubt you will be able
match it with one of the four available L configurations.
73,
Gerald K5GW
In a message dated 10/10/2009 6:17:35 A.M. Central Daylight Time,
mikerauh@yahoo.com writes:
Hello TTers,
I am planing a stack. I would like to get double duty as a 160 M vertical
as well.
I modeled the stack in EZNEC and I can get resonant at about 1.9 MHz at
the minimum height. That is just a guess - I won't really know till I build
the stack. If I add height, of course, I can lower the resonant frequency.
I can series feed or shunt feed at my option. I imagine series feed would
require me to disconnect all the rotor wires with relays or use
common-mode chokes when I am in 160 M mode. For that reason, shunt feed seems
the
best option.
The first yagi in the stack will be at 30 feet. That limits the height of
the Gamma rod or Delta wire to 30 feet also.
Will I be able to match the tower with this limitation? Especially since
the actual resonance might be lower than 1.8 MHz. Would it be better to
avoid having the resonance in the band?
Mike W8GT
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