Kirkby calibration kit alternatives?

[joeqsmith]

Personally, just for learning the basics, I would just use the parts supplied with the Nano.  Or if you want to experiment, maybe make a board with the SOLT and other areas to run what ever experiments you want to run.  If you get to a point where you need to make better measurements at least you will have some background.   What experiments do you want to run?   

[Noy]

Thx for all the clarification.
I think i will go with the Mouser Parts and will not get Male-Male thiny + box.
I don't know for what i need this Male-Male Adaptor. Everything i use (cables are Male - Male, PCB connectors everytime female..) so i don't know for what i can use it.. So i will go for single buy (especially i have to order some parts from mouser already..).

And if i need such a adapter (maybe i will calibrate without a cable at the VNA Port with the N->SMA Female Adapters (https://www.delock.de/produkt/89983/merkmale.html)) i can use a "cheap" chinese and calibrate them out or? Its the same like using a very short cable?

[Mechatrommer]

with a "pogo plug SMA"...

oh no, dont! ..
1) slight wiggling will change characteristic, and where the measurement plane will be? thats why they will ask you to buy another expensive torque wrench. if its thats easy everybody is already doing that and skip the torque wrench.
2) what do you want to mass produce cal kit for? not everybody buying it. you will compete with $4 kit anyway that people buy because they think its good enough.

your provided SDR links are not deep enough... i remember i saw a website at characterizing few SDR-kit, i cant find it right now... the closest thing you should read is something like this..
http://hamcom.dk/VNWA/
https://www.sdr-kits.net/downloads/2014-Rosenberger-Fairview-male-female-Cal-standards.zip
from https://www.sdr-kits.net/Female-12%20GHz-Kit

some sort of hand tuning cal kit, or to see how much batch to batch differ in characteristics. i dont read because i dont own one and afaik they dont include Ln and Cn effect into consideration. you may read yourself and decide if its good enough or what and then tell us something about it. cheers.

[switchabl]

imho no, except with extra effort to screw unscrew for connection and reduce usable life of the connectors. with good continuity/connectivity and good quality 50 ohm Zo thru, connecting to Open and Short will only increase its offset length, the rest of parameters are still the same. connecting to a good Load will still appear 50 ohm to the VNA. but well, this is true given the CAL set is of descent quality, if not, even a SMA cable or the sacrificial adapter connected to your VNA can look funny. this can quite visible beyond 3GHz and much lower with nonsense hunglow grade. ymmv.

Yes, in theory, an ideal adapter will add only delay. And to be fair a good 3.5mm air-line f-f will get reasonably close to that. Your average SMA adapter may not be that ideal. Minicircuits specifies a return loss of only >23dB @<8GHz for theirs. Now imagine connecting your nice 40-45dB calibration load on the other side and calibrating with that. Yes, that is a bit extreme, the adapter will usually be much better then the spec (especially at low frequencies), but you get the point. In particular, unless you have a cal-kit for the other side, you will not be able to check how good it actually is. Sadly so, because it would be much simpler and more economical if we could just have one cal-kit with a bunch of adapters.

Now to be clear, for none-critical measurements you can get away with a lot. On a good lab-grade VNA, you can skip the cal-kit entirely, attach your cables and adapters and run the automatic port extension if you don't care about a few dB. But if you are worried about the 35dB residual mismatch you might hope for with the cheap Rosenberger kit, you should probably worry about adapters.

[joeqsmith]

$400 for a 3.5mm male/female, 6GHz kit with characterized attenuator.  Includes an open end plus a torque wrench.   Data stored on FLASH.   Specs are on the add.  Looking at a similar kit from Kirkby the price is less than half.   May be an option.   

https://www.amazon.com/gp/product/B08LD2JTX7/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

[rubidium]

Has anyone tested out the Applied EM Innovations kit?

[小太]

radar_macgyver mentioned they bought an Applied EM kit while having access to a professional 3.5mm calibration kit... I wonder how the comparison went given that it's almost 2 years later?

For reference, current prices with conversion rate £1=US$1.263

Item	Kirkby £GBP	Kirkby $USD	Applied EM $USD
6 GHz			599
7 GHz	485	578
8 GHz	513	648	649
Torque wrench	150	189	(included)

[radar_macgyver]

I have the 10 GHz version of the Applied EM cal kit. I made some measurements on a FieldFox 9917B that was first calibrated with a Rosenberger RPC-3.50. The Fieldfox was set to full span (30 kHz - 18 GHz) with 1601 points. I then measured the female standards from the Applied EM kit and saved the s1p files. Also grabbed an s1p from the RPC-3.50.

I plotted the impedance, and it seems like the AEM kit does well up to ~10 GHz.

I quit after tearing my hair out for a good 2 hours trying to figure out the METAS tools, so if someone else can use it to generate a model I'd be grateful (and maybe post a link to a tutorial?)

[alan.bain]

Are you trying to use VNA Tool?  I had previously had issues with this and the process I got was

Right-click on the file of measurements, then select Database / Fit Calibration Standard Model (as per the screenshot)

You then choose which type of standard it is and which parameters you don't want to adjust (I would suggest that initially you reduce the set size e.g. remove L2/L3 from the fit for a short) and hit "Start Optimization".   If you try and fit too many it can get into "Not Responding" state which is a bit poor!

[TheSteve]

I have the 10 GHz version of the Applied EM cal kit. I made some measurements on a FieldFox 9917B that was first calibrated with a Rosenberger RPC-3.50. The Fieldfox was set to full span (30 kHz - 18 GHz) with 1601 points. I then measured the female standards from the Applied EM kit and saved the s1p files. Also grabbed an s1p from the RPC-3.50.

I plotted the impedance, and it seems like the AEM kit does well up to ~10 GHz.

I quit after tearing my hair out for a good 2 hours trying to figure out the METAS tools, so if someone else can use it to generate a model I'd be grateful (and maybe post a link to a tutorial?)

Can you give the expected/specified Z0 offset and offset delay for the Applied EM kit. As was mentioned for it to work best you should know some of the parameters, or at least enter what they should ideally be to reduce the variables.

[小太]

I have the 10 GHz version of the Applied EM cal kit. I made some measurements on a FieldFox 9917B that was first calibrated with a Rosenberger RPC-3.50. The Fieldfox was set to full span (30 kHz - 18 GHz) with 1601 points. I then measured the female standards from the Applied EM kit and saved the s1p files. Also grabbed an s1p from the RPC-3.50.

I plotted the impedance, and it seems like the AEM kit does well up to ~10 GHz.

I quit after tearing my hair out for a good 2 hours trying to figure out the METAS tools, so if someone else can use it to generate a model I'd be grateful (and maybe post a link to a tutorial?)

Can you give the expected/specified Z0 offset and offset delay for the Applied EM kit. As was mentioned for it to work best you should know some of the parameters, or at least enter what they should ideally be to reduce the variables.

They posted values in this post as an attachment.
TL;DR for the female load is offset Z_0=54.16Ω and delay=4.77ps

I'll try to derive calibration parameters myself with the data too in a few days, if nobody else has done it by then 

[radar_macgyver]

Per the PDF included with the kit, Z0 offset is 54.16 ohm, delay is 4.77 ps, and loss is 10 Gohm/sec for the female load.
I ran the IN3OTD Octave scripts with the max frequency set to 10 GHz, and got Z0 offset = 54.5 ohm, delay 5.37 ps and loss of 20 Gohm/s. I suspect the optimization is not converging on a good solution since it hits various bounds (in the case of the run I included the results from, the upper bound for loss was 20 Gohm/s).

[小太]

Here are the fitted values by METAS VNA Tools for the entire 0~18GHz range.
The Applied EM kit is only specified up to 10GHz though, so this is just for educational purposes and not a commentary about the kit quality
(I'll do a proper 0~10GHz version in my next post)

Results have been plotted in Mathematica with equations from Keysight application note 1287-11 "Specifying Calibration Standards and Kits".
"Given" values are those included with the Applied EM kit (as reported here), while "Fitted" are those VNA Tools generated

Short F	Offset Z0 (Ω)	Offset delay (ps)	Offset loss (GΩ⋅s-1)	L0 (10-12 H)	L1 (10-24 H⋅Hz-1)	L2 (10-33 H⋅Hz-2)	L3 (10-42 H⋅Hz-3)
Given	51.56	83.61	2.57	-889.07	9989.25	9983.11	-1413.8
Fitted	51.524	81.139	6.2800	-909.96	111076	-14204	340.48
Open F	Offset Z0 (Ω)	Offset delay (ps)	Offset loss (GΩ⋅s-1)	C0 (10-15 F)	C1 (10-27 F⋅Hz-1)	C2 (10-36 F⋅Hz-2)	C3 (10-45 F⋅Hz-3)
Given	50	76.37	1.96	-351.35	-3947	1326.61	-507.08
Fitted	53.549	67.442	2.7871	46.597	-90050	10138	-358.16
Load F	Offset Z0 (Ω)	Offset delay (ps)	Offset loss (GΩ⋅s-1)
Given	54.16	4.77	10
Fitted	54.253	8.4764	-11.561

P.S., Equations from Keysight application note 1287-11 converted to Mathematica form

Code: [Select]

Zr = Quantity[50, "Ohms"];
(* Equations 1.1 and 1.4 *)
\[Gamma]l = \[Alpha]l + I \[Beta]l;
\[CapitalGamma]1 = (Zc - Zr)/(Zc + Zr);
\[CapitalGamma]T = (ZT - Zr)/(ZT + Zr);
\[CapitalGamma]i = (\[CapitalGamma]1 (1 - Exp[-2 \[Gamma]l] - \[CapitalGamma]1 \[CapitalGamma]T) + Exp[-2 \[Gamma]l] \[CapitalGamma]T)/(1 - \[CapitalGamma]1 (Exp[-2 \[Gamma]l] \[CapitalGamma]1 + \[CapitalGamma]T (1 - Exp[-2 \[Gamma]l])));
(* Equation 1.10 *)
\[Alpha]l = (offsetLoss offsetDelay/(2 offsetZ0)) Sqrt[f/Quantity["Gigahertz"]];
\[Beta]l = 2 \[Pi] f offsetDelay + \[Alpha]l;
Zc = offsetZ0 + (1 - I) (offsetLoss/(4 \[Pi] f)) Sqrt[f/Quantity["Gigahertz"]];
(* Equations 1.12 and 1.13 *)
ZS = I 2 \[Pi] f (L0 + L1 f + L2 f^2 + L3 f^3);
ZO = 1/(I 2 \[Pi] f (C0 + C1 f + C2 f^2 + C3 f^3));

(* Example usage with OPEN parameters *)
\[CapitalGamma]i /. ZT -> ZO /. {
   C0 -> Quantity[46.597 10^-15, "Farads"],
   C1 -> Quantity[-90050 10^-27, "Farads"/"Hertz"],
   C2 -> Quantity[10138 10^-36, "Farads"/"Hertz"^2],
   C3 -> Quantity[-358.16 10^-45, "Farads"/"Hertz"^3],
   offsetDelay -> Quantity[67.442, "Picoseconds"],
   offsetLoss -> Quantity[2.7871, "Gigaohms"/"Seconds"],
   offsetZ0 -> Quantity[53.549, "Ohms"],
   f -> Quantity[f, "Gigahertz"]
};
S11 = % /. Cases[Variables[%], v_ /; Head[v] =!= Quantity -> v -> Quantity[v, "DimensionlessUnit"]] /. {
    Quantity[v_, "DimensionlessUnit"] :> v,
    Quantity[v_, 1/"DimensionlessUnit"] :> v,
    Quantity[v_, Sqrt["DimensionlessUnit"]] :> v
};
Plot[Abs[S11], {f, 0, 18}, AxesLabel -> {"Frequency (GHz)", "|S₁₁|"}]


[小太]

Same thing as above, but fitting was limited to just 0~10GHz

Short F	Offset Z0 (Ω)	Offset delay (ps)	Offset loss (GΩ⋅s-1)	L0 (10-12 H)	L1 (10-24 H⋅Hz-1)	L2 (10-33 H⋅Hz-2)	L3 (10-42 H⋅Hz-3)
Given	51.56	83.61	2.57	-889.07	9989.25	9983.11	-1413.8
Fitted	52.319	85.325	1.0887	-965.37	-61723	29349	-2997.3
Open F	Offset Z0 (Ω)	Offset delay (ps)	Offset loss (GΩ⋅s-1)	C0 (10-15 F)	C1 (10-27 F⋅Hz-1)	C2 (10-36 F⋅Hz-2)	C3 (10-45 F⋅Hz-3)
Given	50	76.37	1.96	-351.35	-3947	1326.61	-507.08
Fitted	52.277	77.447	1.2253	-309.12	-12284	219.52	-456.68
Load F	Offset Z0 (Ω)	Offset delay (ps)	Offset loss (GΩ⋅s-1)
Given	54.16	4.77	10
Fitted 1*	77.775	0.76737	340.06
Fitted 2*	54.142	6.2391	10.000

* The "Load F" fitting decided to produce stupid values initially, so I ran it again but forced the offset loss to 10, and it gave more reasonable values. Both results are shown


I'm not really qualified to make a conclusion here (I'm too inexperienced), but if I were to make one anyways:
 - Assuming the VNA was calibrated correctly with the Rosenberger kit (and kit was within spec)
 - Applied EM's short and open have calibration coefficients that seem fitted to a max of 6~8GHz rather than all the way up to 10GHz
 - Applied EM's load coefficients seem to be way off
 - Ignoring the load coefficients (I haven't worked out how to apply them to measured data yet), the load only has a return loss of ≥36dB up to 4GHz, and it progressively gets worse until 29dB at 10GHz, which doesn't sound like it's within spec

[EE-digger]

You can also ask yourself how good your results have to be.  I've done a lot of chip antenna layout and tuning work.  After cal to the end of my VNA cable with SMA standards, I still have to extend it over an SMA to U.FL to another U.FL on the pcb.

In a case like this, you're better off creating your own open, short load on the pcb itself.  Then, just put an RF short on the last connector and run auto or manual compensation for the short.

added - and, of course the frequencies you're working on will affect this big time