"iw3hev, Davide" wrote in message
om...
"Steve Nosko" wrote in message
...
"iw3hev, Davide" wrote in message
om...
Paul Burridge wrote in message
. ..
Hi guys,

Just come across this design for a self-build VNA and wondered what
you thought of the spec:

http://www.geocities.com/robert_laco...us_designs.htm

Hello Paul, I have a similar type under testing but limited working
frequency range 1.8-60 Mhz at www.qsl.net/iw3hev. The performances are
not comparable to the VNA from N2PK but is good for antenna testing.
Regards
iw3hev
Davide

Am I reading the block diag correctly-- in that the contest winner does
not
measure return parameters (S11 or S22) , but only through (S21, S12) the
DUT?
Davide's does return measurements.

Steve,
The unit performs reflection measurements using the internal
directional coupler, the dynamic range is maximum 30 dB. For
transmission measurements is necessary to add a second connector and a
switch. By the switch we can change the type of the measurement from
reflection to transmission.
The switch will change the signals path of AD8302 inputs, for
transmission measurement the directional coupler will became a power
splitter (-15 dB to the first AD8302 input and the rest to the actual
BNC connector-TX). The reflection port of the directional coupler will
be terminated to 50 ohm only, meanwhile the second AD8302 input will
be connected connect to the extra connector (RX). The software for
transmission measurements is not yet ready but I believe shortly I can
post.
iw3hev, Davide

I am confused. Are you describing YOUR unit or the one first referred to.?
I hadn't looked at your design, if it is on the web site. I was referring
to the Robert Lacoste site. That block diagram has no dir coupler shown,
just splitters, so it looks like a through measuring device only. Am I off
base somewhere?

--
Steve N, K,9;d, c. i My email has no u's.