Beginner question;
My Anritsu VNA has the option to save in the memory a trace and then it can
perform basic trace maths (minus, plus, etc).
What if... I do the full S21 two ports SOL calibration, then, still with the
testing fixture connected I connect TX to Rx ports (short) and I save that
trace.
The trace should be very close to a flat line but it will take into account any
testing fixture effects (stray capacitances, alligators, etc).
Finally, I can measure the choke and apply "New trace minus trace in memory".
Is that worth in this case?
Thanks
73, Maximo
________________________________
De: TowerTalk <towertalk-bounces@contesting.com> en nombre de Richard (Rick)
Karlquist <richard@karlquist.com>
Enviado: viernes, 13 de octubre de 2017 15:38
Para: Wes Stewart; towertalk@contesting.com
Asunto: Re: [TowerTalk] CM Choke
On 10/13/2017 5:49 AM, Wes Stewart wrote:
>> On 10/11/2017 6:46 AM, Wes Stewart wrote:
>>> With a decent vector network analyzer, the ports are already
>>> well-known (50 Ohm) terminations. If the round robin you mention was
This is probably largely true, especially as to ham radio
frequencies; it would be hard to imagine an error of more
than a few percent, which would be insignificant for
measuring chokes.
However, if you really want to do things right, you need to
do a full two-port calibration on the network analyzer.
This "calibrates out" any imperfections in the source
and load impedances of the ports. I don't believe the
hobbyist type analyzers are capable of this, because they
don't have a reflection bridge in port 2. (Correct me
if I am wrong). This becomes important at microwave
frequencies where even Agilent can't realize a perfect
50 ohm source.
A poor man's way to fix source mismatch is to simply
pad down the ports with precision attenuators. If you
can stand the loss of dynamic range, this works well.
(Biographical note: I used to design network analyzers
for Agilent).
Rick N6RK
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
TowerTalk Info Page -
Contesting<http://lists.contesting.com/mailman/listinfo/towertalk>
lists.contesting.com
TowerTalk is for discussion of tower and HF antenna construction topics. TT
members have lots of helpful information and are happy to share it.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|