Not sure what you mean by Quality Factor -- but from URL:
http://www.antennex.com/preview/vswr.htm

"As a rule of thumb, any accurate VSWR reading under 2:1 is probably not
worth the effort to achieve if the other elements of your antenna system are
the best you can make them."
--
73- Cambio - Keyboard To You (:-)

"Massi" wrote in message
...
Hi to everybody,
I got the VSWR of an antenna from a Vector Analyzer and I'd like to know
(and how) if is possible to calculate the Quality Factor from it.
Thanks,
Massimo