Tom W8JI wrote:
>
>> Tom W8JI wrote:
>>> A mobile whip loaded with a coil is a series resonant
>>> system.
>>>
>>> Are you saying a GDO will not dip on a mobile whip Bill?
>>
>> The bottom of the coil is connected to the chassis through the low
>> impedance of the feed system. The vertical radiator has capacitance to
>> the chassis (of course it has inductance, too). Sounds parallel to me!
>
> So the loading coil is like a trap, and the coax sees an open circuit?
No. The vertical part has a capacitve reactance and a resistance, part
of which is radiation resistance. The whole system has a lower Q than a
lumped-constant parallel tuned circuit. The impedance seen by the
feeder is thus lower.
> The idea a GDO can sort "good resonances" that make low impedances from
> "bad resonances" that make high impedances seems pretty strange to me.
> Can you tell me how it does that, rather than just finding some type
> of resonance at the point where it is inserted?
I certainly never said anything like that.
> Is there a way to measure impedance and Q with it Vic?
No, although the sharpness of the dip gives a clue to the Q.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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