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Kirkby calibration kit alternatives?
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G0HZU:
If you haven't downloaded it already here is the bundled s1p custom data on the Kirkby male SHORT in a text file and I've listed the custom corrections below.


--- Quote ---Male short. (Use SHORT(F) or SHORT -M- depending on model of VNA - see notes above) **
Minimum frequency:  0 GHz
Maximum frequency:  7.0 GHz
Offset Zo: 50.0 ohms
Offset loss: 3.0 G ohm/s
Offset delay: 57.997  ps

--- End quote ---

There is only a delay correction and I get the phase response below. This does not look good but I guess the male part of the kit will be used less often. The older 8753 VNAs kind of default to 'insertable device' calibrations so they would often use both male and female kits for a full two port calibration. In this case it's debateable if the Kirkby kit is 'fit for purpose' for a decent 6GHz lab VNA like an 8753?
G0HZU:
With my manual optimiser for the Lx corrections I can flatten the response and it's easier if I drop the Zo slightly. But I get a slight fixed phase offset with the flat response. Not sure what has happened there. Maybe it needs to be measured again on a VNA?
How does it look if you try and optimise it with METAS?

It looks better with just a Zo tweak but maybe also try it with Lx corrections. It's a shame this Lx correction can't be added to the 8753 firmware in some way. It might be possible to bodge it in to the firmware with a crude patch?
hendorog:

--- Quote from: G0HZU on February 25, 2018, 05:34:31 pm ---If you haven't downloaded it already here is the bundled s1p custom data on the Kirkby male SHORT in a text file and I've listed the custom corrections below.


--- Quote ---Male short. (Use SHORT(F) or SHORT -M- depending on model of VNA - see notes above) **
Minimum frequency:  0 GHz
Maximum frequency:  7.0 GHz
Offset Zo: 50.0 ohms
Offset loss: 3.0 G ohm/s
Offset delay: 57.997  ps

--- End quote ---

There is only a delay correction and I get the phase response below. This does not look good but I guess the male part of the kit will be used less often. The older 8753 VNAs kind of default to 'insertable device' calibrations so they would often use both male and female kits for a full two port calibration. In this case it's debateable if the Kirkby kit is 'fit for purpose' for a decent 6GHz lab VNA like an 8753?

--- End quote ---

Yes I think you have a point. Even with corrections it is not great.

This is what the optimiser spits out when I remove the data above 7GHz. L1 has hit the limit.


--- Code: ---offs_delay = 54.877614 ps
offs_loss = 2.058719 Gohm/s
offs_Z0 = 51.050105 ohm
L0 = -3687.287669 * 1e-12 H
L1 = 10000.000000 * 1e-24 H/Hz
L2 = -978.814153 * 1e-33 H/Hz^2
L3 = 2713.293761 * 1e-42 H/Hz^3

Residual RMS error : -48.553224 dB

--- End code ---


suj:

--- Quote from: G0HZU on February 25, 2018, 05:51:58 pm ---How does it look if you try and optimise it with METAS? It looks better with just a Zo tweak but maybe also try it with Lx corrections.

--- End quote ---

Results from Metas. A better result if the optimizer can change "Offset Z0" - column "Agilent definition". Anritsu and R&S probably don't support Z0 changes and the effects can be seen for Z0 = 50 Ohms.





Normalized to S1P.
Black - data from S1P
Red/brown - HP (with optimized Z0)
Orange - fixed Z0



suj:

--- Quote from: G0HZU on February 25, 2018, 05:51:58 pm ---...It's a shame this Lx correction can't be added to the 8753 firmware in some way.

--- End quote ---

By the way. It should be possible to do it off-line with Metas. It has a built-in driver for the 8753 and 8720 series (as well as 8510C, ENA, PNA). You can make measurements and off-line error correction using this software. Definitions of the "short" element that you can prepare have the option of defining L.
The procedure is shown in the tutorial on the program's website.
It looks like a Swiss army knife  ::)
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