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No Fringing Capacitance Correction in KC901V

By soasystem •  2017-10-10 16:04:21 •  932 clicks
from study, i suspect fringing capacitance effect on open transmission line or calibration kit will have effect on the accuracy of the KC901 VNA series measurement (including the latest KC901V). either the VNA designer has put default values for it or no at all in the calculation model, i dont know. but different open calibration standard kit will have different fringing capacitance effect, this will effect s-parm correction matrix if not input the right values, hence giving wrong measurement. i suggest KC901V designer will open up calibration kit data for user to enter in firmware, similar to brand name VNA like Keysight and Anritsu VNA. because i need to get 3rd party SMA Calibration Kit to move reference plane further away from KC901V for convenience measurement, most good cal kit will provide the data and parameters, but i cannot see it inputable in KC901V firmware, except just offset length. now, i cannot guarantee the KC901V will give me the right measurement, maybe just estimate.
13 Reply | until2018-11-18 13:32Add a reply
    VK3NH  9 days ago#1 -Reply



    VK3NH  182 days ago#2 -Reply

    Any news on the firmware update?

    soasystem  214 days ago#3 -Reply

    Schwarz. if Deepace can use existing format, so Kirkby will do easy job they doesnt have to study Deepace format, if they are happy because it is compatible with their work, maybe they can recommend KC901V with their calibration kit, so hopefully will increase sale. Hope it helps. I wish you good luck. (damned my message is too long cant fit in a single reply).

    soasystem  214 days ago#4 -Reply


    soasystem  214 days ago#5 -Reply

    btw, i heard some people discussing about fringing inductance effect or some sort. it is the inductive effect vs frequency in SHORT standard calibration kit, similar to capacitive effect in OPEN standard. but i cant find any reference to this in the net maybe this is a new concept or still classified, or maybe its even bogus i dont know, but its been discussed by people sharper than me. Even Kirkby Microwave with their older HP VNA model doesnt support fringing inductance. Just want to share some unproven info... btw asking Deepace to support fringing inductance maybe is too much, i will be happy enough if its going to support fringing capacitance only.

    and as for another suggestion, maybe Deepace can make KC901V to read calibration kit coeeficients in the form of file from the microSD card (Touchstone format), so we dont have to key in many parameters manually, worst if we keep changing calibration kit in measurements. like me, sometime i change from male to female connection, so i have to recalibrate with different gender, both of my male and female sma cal kit have very different offsets values. so typing in frequently even the existing simple parameters in KC901V firmware can be a pain. i suggest Deepace can make compatible to read Agilent/HP coefficients touchstone file format, i will be glad to provide the file format sample if you want.

    Why i suggest to use existing brand name format? (i suggest HP format because its most popular that i know) is because Kirkby Microwave who provides custom unique characterization and traceability of each of their calibration kit will produce well known brand format such as Agilent/HP, Tektronix, Anritsu, Copper Mountain and Rohde

    soasystem  214 days ago#6 -Reply

    wow just notice this messages. this is good news good reply from Deepace. i will look forward for this. with this feature i believe it can increase value for the KC901V closer to professional grade brand VNA and erase some negative comment from professionals out there. if this feature is working as expected, i will sure spread words to our forum member and hope to increase sale. Hope Deepace success!

    VK3NH  218 days ago#7 -Reply



    Can you please give us an update on progress with the firmware update to address this aspect?

    regards Noel

    VK3NH  251 days ago#8 -Reply

    To the design team,

    Thanks for your efforts on this additional aspect. Thanks to the KC901V project, I am learning new things all the time.

    regards Noel

    BG8NPK  251 days ago#9 -Reply

    Our team developed this function and it is in test processing. When we test this function we will release a firmware to update the instrument.

    soasystem  2017-12-28#10 -Reply

    hi mjohnellis, i think i agree with you, we should be able to get some ballpark from it, furthermore i bought a cal kit from Kirkby Microwave. the fringing capacitance effect for the Open standard is too small to worry about i guess. if i tune the offset length to the mean value (which is near center operating freq of KC901V ie at 3.5GHz), i will have max deviation of 0.162 mm (0.54 ps), my uneducated guess, this should give little impact to the accuracy. but still, its better to have a device that accepts variable delays for each frequency, like commercial one. i'm guessing this only need to be done in firmware (no hardware modification needed) and the KC901V's designer only need to find a proper book to read further on this matter (mathematical formulation).


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