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Old May 2nd 06, 11:49 PM posted to rec.radio.amateur.homebrew,sci.electronics.design
Joerg
 
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Default Need further info on network analysis terms...

Hello Paul,


Reading through the instructions for this VNA it mentions some
important accessories; power spitters, 6db attenuators, 50 ohm
terminations, opens, shorts and throughs. What exactly is a "through"?



Probably a matched connection from point A to point B. This is often
used to provide a certain line length for purposes of equalizing a time
delay. You'll see that on many directional coupler assemblies, like when
you open the front pod of a HP4191A.


And is it possible to make up accurate opens and shorts oneself that
are good enough for calibration purposes up to 1.3Ghz? Not talking
about any absolute standard here, like you'd get from HP themselves;
but just mid-tolerance stuff that'd be sufficient for reasonably
accurate amateur experiments?



For hobby use, probably. The lab analyzers come with a calibration kit.
The 50ohm resistor is a barrel with a connector. The open is just that,
a tube that looks like the innards of the connector have been scraped
out. The short is a connector with a precision gold plate in there that
guarantees a solid flat contact between center and rim. Believe it or
not, the 50ohm resistor of mine is now about 52.5ohms. Couldn't believe
it, considering the profit margins on that stuff.

For the terminator I suggest to look at chip resistors. What is most
important is to keep all the contact surfaces clean.

Regards, Joerg

http://www.analogconsultants.com