Your answer to the question about bidirectional couplers was they do not
compensate for phase shift. Let me ask it again:

Do the measuring ports of a bi-directional coupler accurately represent or
preserve the relative phases of the signal?

To put it another way is the phase shift of the driving and reflected
signals changed by the same about?

Thanks - Dan kb0qil

The phases seen at each coupled port should be identical to the phase of the
forward and reflected signals. This is easily verifiable, and frequency
independant, as follows:

No load -- forward and reverse amplitudes equal, and in phase;
Short circuit at output -- forward and reverse amplitudes equal, and 180
degrees phase difference;
50 ohm load -- reverse than forward by = specified coupler directivity,
and phase difference can 0 theta +/ 180.

This is only true if the frequencies are low enough such that the standards
do not require quantification by the use of "Standard definitions" -- see
www.vnahelp.com.


Regards,

Frank