Port 00 or Port 01, that used for one-port measurement of s11, may not be a
good 50+j0 source over your frequency range. You exhibit everywhere better
than 15 dB return loss which is pretty good, but the periodicity of the
measurement is a bit disturbing.
Try recalibrating and remeasuring with a 6 dB attenuator on the s11 port.
That will assure a return loss in excess of 12 dB and stabilize the
impedance of that port.
Dave - W?LEV
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On Mon, Jan 6, 2020 at 12:28 AM Robin Midgett <K4IDC@...> wrote:
I've calibrated my NanoVNA & connected it to an approximate 350' length of
coax with a known good dummy load on the opposite end. The S11 plot is
attached...not pleasing at all.
Can anyone on the list say what the cause may be?
I have ideas, but I don't want to sway anyone's opinion..
--
*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*
