Richard Clark, KB7QHC wrote:
"A poor physical open or physical short will never be improved by ANY
transmission line mechanics."

An open-circuit 1/4-wave stub is an open circuit at both ends,
physically. As such, its input is a poor short-circuit until it receives
a reflection from its far end. After the reflection reaches the stub`s
input, it becomes a virtual short-circuit. This occurs at its "poor
physical short" input.

This is a dramatic improvement by transmission line mechanics when this
is the desired effect.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
An open-circuit 1/4-wave stub is an open circuit at both ends,
physically.

Let's look at a 1/4WL open stub.

source ----------------------------------+
|
| 1/4WL
|
|
open

The transmission line and stub are the same Z0 and
both are lossless.

The virtual impedance at point '+' is zero but there
is no physical impedance discontinuity at point '+'.
Are there any reflections originating at point '+'?

If we straighten out the line,

1/4WL
source-----------------------------------+------------open

Are there any reflections originating at point '+'?
--
73, Cecil http://www.w5dxp.com

On Fri, 13 Apr 2007 20:34:56 -0500, (Richard
Harrison) wrote:

This is a dramatic improvement by transmission line mechanics when this
is the desired effect.

Hi Richard,

This kind of drama is found only on the stage.

A poor open is a poor short in reflection. Ever try tuning one that
didn't wander the landscape? Burning money to achieve a working
solution does not render it a dramatic improvement when other methods
(like simply building a good shorted halfwave) are better.

Give me a reason why you suffered to build an open quarterwave, and it
will embrace the issues of quality I already covered.

73's
Richard Clark, KB7QHC