K7ITM wrote in news:1186788470.852002.260460
@b79g2000hse.googlegroups.com:

On Aug 10, 2:28 pm, Owen Duffy wrote:
...
I don't think you can compensate for lack of f/b ratio in the coupler,
for example because the coupled lines are too long.
...
I'm curious what you mean by that, Owen...

Tom, I was thinking of several instruments, all of the coupled lines type
of construction, that on a s/c and o/c failed to indicate rho=1, and showed
similar readings when physically reversed, suggesting it was not just a fwd
/ rev matching issue, there was something about the coupler that was too
dependent on the location of the SWR pattern relative to the coupler. Since
they worked better at lower frequencies, the length of the coupler was
likely to be a contribution.

Owen