On Sun, 27 Dec 2015 12:15:51 -0000, "gareth"
wrote:

There are two aspects of vector analysis under consideratiom; the first,
as for antennae measurement is to assess the amplitude and phase of
reflected
power from various circuits, which is where the interest in the VNWA arises,
but the second is the analysis of complex modulation, particularly
where there are constellations.

Antenna analyzers do NOT demodulate signals or present constellation
plots. They only measure antenna and transmission line impedances.
For a constellation plot, you'll need a service monitor with the
decoding software for whatever modulation type you want to view.
Compared to an MFJ-259/269, that will increase your test equipment
budget about 500 times. Or you can search for an RTL-SDR
implimentation that displays a constellation plot. Maybe this one:
http://yo3iiu.ro/blog/?p=1393
Lots of jitter, but cheap.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558