[Elecraft] Vertical for 40 & 80 - follow-up

[Ron D'Eau Claire]

Keith KD1DE wrote:

Anyway, I picked up a Hustler 80 meter resonator.  Hustler says it is just a
big coil, not a resonator.  Hmmm.

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A short antenna is capacitive. It requires inductance to make it resonate,
i.e. show zero reactance at the operating frequency. So a coil for a short
whip to bring the reactance down to zero is often called a "resonator". 

The antenna tuner does the same thing. It provides "base loading" or
inductance at the base to achieve resonance, since it's at the feed point.
Moving the coil out on the antenna improves the current distribution.  The
trade-off is that the less antenna there is between the coil and the far
end, the more coil you need to achieve resonance. Coils introduce their own
ohmic losses, especially at RF, so the coil losses go up as it gets bigger.
The general rule of thumb is that center loading is more effective than base
loading. It provides better current distribution without introducing
excessive ohmic losses. If the system is naturally resonant, your antenna
tuner only needs to provide the impedance transformation required to match
the feed point impedance of the antenna to the 50 ohm impedance load needed
by your rig.  

Good going on your 80, 40, 30, 20, meter short vertical combination. It's
effectiveness is highly dependent upon the ground on the lower frequencies.

Ron AC7AC