On 3/4/2014 7:04 PM, Charlie Cunningham wrote:
I'd also like to be able to apply VNA measurements to some of my HF antennas
and I might be willing to take a laptop out there to do that, but I could
also just calibrate out the feedline to move the measurement plane out to
the antenna and do the measurments from indoors! Would be nice to have the
capability!
Charlie,
Virtually all of the major vector analyzers can write impedance data
files in a standard plain text format (called Touchstone) that can be
imported by modeling programs like SimSmith. They also allow you to do
TDR of the system, so you can subtract out the feedline. From there you
can design matching networks.
There's a piece on my website that lists several decent analyzers, then
shows you to use SimSmith to do these things. SimSmith is FREE, and runs
in Java. Dan, AC6LA, has some wonderful Excel spreadsheets that work
with this data. One of them will take open circuit and short circuit
sweeps for a piece of transmission line and compute Zo, Vf, and
attenuation vs frequency. Most of his spreadsheets are free. Dan also
sells a spreadsheet that automates EZNEC and, I think, will do
optimization.
73, Jim K9YC
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