I would like to know if the follow technique will work to measure resonance of
an antenna. I know have a working HP 8405a. It has been a struggle to repair it
and to align it, however it now appears to be working.

My plan is to connect a bi-directional coupler to the 8405a. The coupler will be
terminated in a 50 Ohm terminator. The phase will be read for this
configuration. The next step is to replace the 50 Ohm terminator with a direct
connection to an unknown antenna. I will then change the frequency until the
phase angle matchs the 50 Ohm phase angle.

Does this make sense?

What are the draw backs?

How close will this method get compared to a noise bridge?

Thanks - Dan kb0qil