[TowerTalk] resonance/swr/impedance plots

[Bill Coleman]

On 11/30/00 0:14, Guy Olinger, K2AV at k2av@contesting.com wrote:

>A tuner does not make an antenna resonant. 

Right, it makes the antenna SYSTEM resonant. A conjugate match exists 
from the tuner all the way out to the antenna. 

>Consider that capacitor a one-piece antenna tuner. A tuner does not make
>an antenna resonant, it makes the SYSTEM resonant from the view point of
>the transceiver or connecting coax.

It makes the WHOLE SYSTEM resonant in a conjugate match. 

>Resonance is one of those sloppily used words that also has a very
>specific technical meaning, not all that closely matching the general
>usage.

I thought it meant that all the reactive components were in balance, 
leaving only the resistive component.

>Appearance of resonance = SWR is low. 

In a tuned doublet fet with open wire, the SWR may actually be high on 
the open wire, but the system is still in resonance.

>You can make the SYSTEM resonant at 75 meters with coils, taps, etc. But
>the ugly low efficiency and narrow bandwidth will be governed by the
>fact that the whip itself is not anywhere close to resonant on 75
>meters.

Thought problem: what would happen if the coils, taps, etc, were all made 
out of perfectly lossless components? Sure, the bandwidth would still 
likely to be narrow, but the efficiency would skyrocket.


Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901


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