"Richard Clark" wrote in message
...
On Tue, 5 Oct 2004 09:10:19 -0500, "John Smith"
wrote:

I don't understand. Please enumerate the issues. What do you mean B1/A1 is
off the mark?

Hi John,

You should get 1.0 @ 180° (the definition of a short).

Well, that's not possible when feeding a length of RG58 at 400 MHz, is it?
Remember, I said that there was about a 5 foot length of RG58 between the
directional coupler and the load. How can one get 1.0 reflected to the
coupler when the load is a short? That requires zero loss coax.


If they are off the mark, how can the Z be close enough?

Because what you DID measure, was used as a correction factor per:
|Rho| = B2·A1/A2·B1 = 0.695·1/1.08·0.79 = 0.815
(or you skipped that step)

I did that. As far as I can determine, I did it like the HP application note
said to do it.

Thanks for your comments.

John