Jim,
Thanks for pointing me in the direction of Zplots - I'd not appreciated
what it can do, although I'm a big fan of AC6LA's TLD software.
I just downloaded Zplots and ran open and short S11 tests on the line. I
plugged the values Zplots gave me for Zo, Vf, K0, K1 and K2 into TLD,
however it then predicts losses very different from my measured losses.
But, interestingly, if I use TLD's default parameters for Wireman 551 it
predicts losses very close to what I measure!
It's not clear to me yet why Zplots would give me line parameters so
different from TLD's parameters for Wireman 551.
I need to explore this some more because if Zplots can produce
believable results it would save me a lot of number crunching :)
Steve G3TXQ
On 09/08/2013 16:55, Jim Brown wrote:
Another way to get transmission line parameters from VNA or VIA
measurements is to measure S11 with the far end open and shorted, or
to measure S21 and export the data to AC6LA's Zplots spreadsheet.
I've used this with good results for 50 and 75 ohm coax, and for
closely spaced parallel wire line in the range of 90 ohms.
Although S21 data and S11 data should produce the same results, Dan
told me that users of his spreadsheet reported more consistent results
when S11 data sets were used. I've tried both, and agree that the S11
data sets are the better way.
There's a lot of useful stuff on Dan's website. http://www.ac6la.com/
73, Jim K9YC
On 8/8/2013 2:59 PM, Steve Hunt wrote:
I managed to find time today to produce a web page on my measurements.
For anyone interested:
http://www.karinya.net/g3txq/wet_ll/
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