The normal way to do it on the nanovna is a bit different. You attach the
near end of the coax to the nanovna, then calibrate (using the
open/short/load calibration loads) at the far end of the cable. Then you
attach the antenna at the far end - all measurements then show the
performance of the antenna itself, having compensated for the coax
properties (primarily length and attenuation). This is more accurate than
the RigExpert's calculation, since as Roger noted, RigExpert uses a data
base of cable types - but any given actual cable will only be 'close' to
the data base values, whereas using the nanovna calibration measures the
actual values.
You can alternately use the "edelay" setting on the nanovna to subtract the
length of the cable, if you look up its properties and enter the correct
value for your length of coax. This also is only approximate, and is
similar to what the RigExpert is doing. You can also use the nanovna to
measure the cable's electrical length, and use that value to set the
edelay, but those are all manual steps, so calibration at the end of the
cable is usually just as easy.
Stan
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On Thu, Dec 8, 2022 at 6:49 AM Phil, WF3W <WF3W@...> wrote:
Hello all XMAS-gift hopefuls,
Is there a way/method/technique for subtracting coax length from readings,
as can be done in Rig-Expert's ANTScope, sftwr?
73
Phil, WF3W
