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