Brian,
As a reference point, when calibrated, the HP 8753D has a linear magnitude reflection uncertainty of 0.015 or so when the reflection magnitude is near 1.
I am not sure if that means the repeatability is limited to that or if that is due to imperfections of the standards used.
(Source: Quick Reference Guide, 08753-90259, page 7-5)
--John Gord
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On Tue, Jun 14, 2022 at 02:45 PM, Brian Beezley wrote:
Measurement of a short at the VNA connector after clearing cal:
49002000 -0.869956992 0.080768176
49126750 -0.869913280 0.080994536
49251500 -0.869870784 0.081221216
49376250 -0.869828352 0.081447216
49501000 -0.869784000 0.081672776
49625750 -0.869736192 0.081898376
49750500 -0.869684800 0.082123680
49875250 -0.869630720 0.082347872
50000000 -0.869575232 0.082570920
After calibrating:
49002000 -1.000384927 -0.000153716
49126750 -1.000387430 -0.000148167
49251500 -1.000389814 -0.000142248
49376250 -1.000392199 -0.000138649
49501000 -1.000394344 -0.000137316
49625750 -1.000395775 -0.000135393
49750500 -1.000395656 -0.000129219
49875250 -1.000393629 -0.000117017
50000000 -1.000389934 -0.000100459
After switching to MA mode. File stayed in RI mode but data changed:
49002000 -0.999972800 0.000051251
49126750 -0.999974336 0.000058021
49251500 -0.999975360 0.000064329
49376250 -0.999976000 0.000067545
49501000 -0.999977344 0.000067800
49625750 -0.999980672 0.000067987
49750500 -0.999986496 0.000071876
49875250 -0.999994304 0.000081417
50000000 -1.000003099 0.000095119
These are excerpts of a 401-point file from 0.1 to 50 MHz. At lower
frequencies the last data set is beyond -1 like the second one.
Observations:
1. |S11| > 1 after calibration.
2. MA mode leaves file in RI mode but affects the data.
Brian
