Paul:
In response to your direct question, I associate voltage directly with
the term wave. An EM wave having a certain "voltage" and "current" is
traveling along the length of the transmission line. At any point
along the line, the voltage and current level of the wave will be a
function of input voltage to the line, the line attenuation, the line
length and the line phase properties.
Voltage delivered back to the tuner input: In the steady state
condition, there will be a steady state voltage developed at the tuner
output. This steady state voltage will be equal to the voltage
created at the tuner output from the arriving reflected wave(s)
originating at the antenna plus the reflected voltage created from
these incident waves. The reflected voltage(s) at the tuner output
are equal to the incident voltage multiplied by the tuner output
reflection coefficient.
Since a voltage is developed across the tuner output it must be
divided/delivered/flow into the individual components within the
tuner. It can't just "stop" at any one tuner component. When the math
is done in detail, it can be proven that the resulting voltage at the
tuner input is the negative of the initial reflected voltage at the
tuner input. When added together, these two voltages cancel and hence
the initial reflected "wave" is canceled. Since there is no
reflection, the tuner appears to have a 1.0:1 VSWR. This is the basis
upon which a conjugate match tuner works. It is important to note
that the steady state condition must be reached in order for the tuner
to work properly.
I have derived all the math in detail. If interested I can send it
along.
73
Steve VE9SRB
______________________________ Reply Separator _________________________________
Subject: Re: Re[2]: [TowerTalk] Mismatch Loss and Tuners
Author: "Paul Christensen" <paulc@mediaone.net> at InterNet
To: <towertalk@contesting.com>
Date: 8/25/98 1:02 PM
I was with you on your first two paragraphs, but when I read the following
statement, it was time to ask for clarification:
> voltage at the tuner output. This voltage will be delivered back to
> the tuner input through the tuner components. The voltage delivered
> back to the tuner input will be the negative of the initial reflected
> voltage at the tuner input causing a complete cancellation of the
> initial reflection. Hence, the steady state 1.0:1 VSWR.
Let's not confuse the application of the following added elements, all of
which contribute to what is being discussed here: Voltage on the
transmission line, current on the transmission line, the forward wave, the
reflected wave, and the phase relationship between voltage and current on
the transmission line.
What I don't understand is your application of the term "voltage delivered
back to the tuner input," and "ALL of the voltage will not be re-reflected."
The "wave" is moving and reflecting, not the voltage. The
antenna-to-transmission line mismatch creates a reflected wave, not a
reflected voltage. True, the reflected wave's voltage will be 180-degrees
out of phase with the reflected current. From your statement above, how are
we getting to a 1:1 based on your fourth paragraph?
-Paul, W9AC
>
> The difference between this discussion and that of Walt Maxwell's is
> that Walt does not start by considering the initial state of the
> tuner. He immediately "assumes" that all of the transmitter power is
> delivered through the tuner, some is reflected by the antenna and then
> ALL is re-reflected at the tuner output. His initial assumption may
> support his conclusion but it does not accurately describe the
> operation of the tuner, nor all of the voltage reflections and
> cancellations that occur. With a lossless transmission line between
> the tuner and antenna his results are numerically correct, however, I
> am uncertain if this would be true when considering a case with
> transmission line attenuation.
>
> In any event, even considering the transmission line losses, the
> matched antenna will radiate more steady state power than the
> mismatched antenna and tuner. Remember that with the tuner, the
> reflections from the antenna must travel the transmission line twice
> before arriving back at the antenna.
>
> Which "works" better - matched antenna or mismatched antenna/tuner?
> The answer to this question requires a much more involved analysis.
> In order to "work", the transmit system only needs to provide a
> useable signal level at the receive site. In many cases, both will
> "work" quite well.
>
> 73, Steve, VE9SRB
>
>
>
>
>______________________________ Reply Separator
_________________________________
>Subject: Re: [TowerTalk] Mismatch Loss and Tuners
>Author: kn6di@groupone.net
>Organization: Global Pack & Mail at InterNet
To: <towertalk@contesting.com>
>Date: 8/24/98 10:22 PM
>
>
>Wouldn't be great if people could talk in plain english and discuss this
thread
>in a straight forward manner instead of every one trying to get the last
piece
>of fly S--- out of the black pepper.
>It would be nice for a plain statement of facts of what works and does not
work.
>As we know no 2 antennas work the same because the conditions are not/never
the
>same. This could go on until cycle 30 at least.
>Hank KN6DI
>
>
>J
>
>
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>
>
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>
>
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