"Have searched the net, but did not find a copy of the QEX 2017/05. Do you know any source for this reference?"
Try searching for, or emailing, the author. Often they will provide a copy to you as a courtesy.
Also try searching for related material to FA-VA5 antenna analyzer. It should be easy to find on web.
He has also written material showing how to connect his unit to DG8SAQ VNWA software.
(Very powerful software but with a steep learning curve.).
