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March 6th 06, 08:23 PM posted to rec.radio.amateur.antenna

Owen Duffy

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Reflection Loss

On Mon, 6 Mar 2006 04:49:53 -0600, (Richard
Harrison) wrote:

Richard,

You originally stated:

On page 99 of Terman`s 1955 edition of "Electronic and Radio
Engineering" (my textbook was an earlier edition) is found the formula
to convert the reflection coefficient into SWR or vice versa. These
two parameters are innexorably locked together by formulas (4-22a) and
(4-22b).

You are squirming away from the accuracy of your assertion that Terman
calculates reflection coefficient from SWR, ie the "or vice versa" in
your statement.

The reflection coefficient is a complex number with magnitude and
phase, as you acknowledge when you later say "It is true that the
reflection coefficient is a vector ratio of the reflected voltage to
the incident voltage at the load".

In formula 4-22b of my copy of Terman, the term on the lhs is |rho|,
which is the magnitude of the reflection coefficient.

No, you cannot calculate the reflection coefficient from SWR alone,
but you can calculate the magnitude alone, but that is less
information than the reflection coefficient.

To illustrate, and as you know, the reflection coefficient at a point
can be used with the line propagation constants to calculate the
impedance at another point on the line. You cannot do that with the
magnitude of the reflection coefficient.

You have misrepresented Terman, he does not calculate the reflection
coefficient from SWR (at least not in my copy).

Owen
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