Author Topic: Kirkby calibration kit alternatives?  (Read 63339 times)

0 Members and 3 Guests are viewing this topic.

Offline Noy

  • Frequent Contributor
  • **
  • Posts: 361
  • Country: de
Re: Kirkby calibration kit alternatives?
« Reply #200 on: November 19, 2020, 01:49:33 pm »
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?


 

Offline Mechatrommer

  • Super Contributor
  • ***
  • Posts: 11714
  • Country: my
  • reassessing directives...
Re: Kirkby calibration kit alternatives?
« Reply #201 on: November 19, 2020, 02:03:58 pm »
with a "pogo plug SMA"...
oh no, dont! :palm:..
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.
« Last Edit: November 19, 2020, 02:06:35 pm by Mechatrommer »
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline switchabl

  • Frequent Contributor
  • **
  • Posts: 445
  • Country: de
Re: Kirkby calibration kit alternatives?
« Reply #202 on: November 19, 2020, 02:25:30 pm »
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.
 

Offline rubidium

  • Regular Contributor
  • *
  • Posts: 105
  • Country: us
Re: Kirkby calibration kit alternatives?
« Reply #203 on: May 20, 2021, 05:21:57 pm »
Has anyone tested out the Applied EM Innovations kit?
 

Offline 小太

  • Contributor
  • Posts: 18
  • Country: au
Re: Kirkby calibration kit alternatives?
« Reply #204 on: February 07, 2024, 08:02:28 pm »
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
ItemKirkby
£GBP
Kirkby
$USD
Applied EM
$USD
6 GHz599
7 GHz485578
8 GHz513648649
Torque wrench150189(included)
 
The following users thanked this post: edavid

Offline radar_macgyver

  • Frequent Contributor
  • **
  • Posts: 748
  • Country: us
Re: Kirkby calibration kit alternatives?
« Reply #205 on: February 08, 2024, 09:14:11 pm »
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?)
« Last Edit: February 08, 2024, 09:16:36 pm by radar_macgyver »
 

Offline alan.bain

  • Regular Contributor
  • *
  • Posts: 93
  • Country: gb
Re: Kirkby calibration kit alternatives?
« Reply #206 on: February 08, 2024, 11:26:31 pm »
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!

« Last Edit: February 08, 2024, 11:28:30 pm by alan.bain »
 
The following users thanked this post: ON7CH

Offline TheSteve

  • Supporter
  • ****
  • Posts: 3785
  • Country: ca
  • Living the Dream
Re: Kirkby calibration kit alternatives?
« Reply #207 on: February 10, 2024, 07:47:16 am »
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.
VE7FM
 

Offline 小太

  • Contributor
  • Posts: 18
  • Country: au
Re: Kirkby calibration kit alternatives?
« Reply #208 on: February 10, 2024, 09:01:30 am »
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  :)
 

Offline radar_macgyver

  • Frequent Contributor
  • **
  • Posts: 748
  • Country: us
Re: Kirkby calibration kit alternatives?
« Reply #209 on: February 12, 2024, 03:35:04 am »
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).
 

Offline 小太

  • Contributor
  • Posts: 18
  • Country: au
Re: Kirkby calibration kit alternatives?
« Reply #210 on: February 22, 2024, 03:35:18 am »
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 FOffset 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)
Given51.5683.612.57-889.079989.259983.11-1413.8
Fitted51.52481.1396.2800-909.96111076-14204340.48
Open FOffset 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)
Given5076.371.96-351.35-39471326.61-507.08
Fitted53.54967.4422.787146.597-9005010138-358.16
Load FOffset Z0
(Ω)
Offset delay
(ps)
Offset loss
(GΩ⋅s-1)
Given54.164.7710
Fitted54.2538.4764-11.561

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|"}]
« Last Edit: March 31, 2024, 02:23:10 pm by 小太 »
 

Offline 小太

  • Contributor
  • Posts: 18
  • Country: au
Re: Kirkby calibration kit alternatives?
« Reply #211 on: February 22, 2024, 04:11:33 am »
Same thing as above, but fitting was limited to just 0~10GHz

Short FOffset 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)
Given51.5683.612.57-889.079989.259983.11-1413.8
Fitted52.31985.3251.0887-965.37-6172329349-2997.3
Open FOffset 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)
Given5076.371.96-351.35-39471326.61-507.08
Fitted52.27777.4471.2253-309.12-12284219.52-456.68
Load FOffset Z0
(Ω)
Offset delay
(ps)
Offset loss
(GΩ⋅s-1)
Given54.164.7710
Fitted 1*77.7750.76737340.06
Fitted 2*54.1426.239110.000

* 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
« Last Edit: February 22, 2024, 04:34:27 am by 小太 »
 
The following users thanked this post: radar_macgyver

Online EE-digger

  • Frequent Contributor
  • **
  • Posts: 391
  • Country: us
Re: Kirkby calibration kit alternatives?
« Reply #212 on: February 23, 2024, 06:33:30 pm »
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
 

Offline joeqsmith

  • Super Contributor
  • ***
  • Posts: 12280
  • Country: us
Re: Kirkby calibration kit alternatives?
« Reply #213 on: September 07, 2024, 05:14:32 pm »
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?)

Sorry for the necropost.  I had watched the METAS video and they did not go into any details on how to accomplish this.  Going through this thread, I too am curious how to derive the coefficients for an unknown set.   

The last time I did this, I used one of the local members Matlab scripts. I would like to try this with METAS.  Any pointers to save my hair are appreciated.   

Also:
https://www.eevblog.com/forum/testgear/kirkby-calibration-kit-alternatives/msg1437115/#msg1437115
SUJ, nice job with the waveguides.  I am on a similar path.   


Offline shabaz

  • Frequent Contributor
  • **
  • Posts: 574
Re: Kirkby calibration kit alternatives?
« Reply #214 on: September 07, 2024, 07:09:58 pm »
Not read the entire thread (too long!) but I was in a situation where I had an OK-ish quality, new OSL Tee, but without the coefficients. I asked Dr. Kirkby nicely, and he was kindly willing to measure it and provide the coefficients for me. The price was extremely reasonable (this was about five years ago). So, that might be an option for the cases where someone's ended up with a cal kit (say from eBay) which might accidentally be missing the data.

Recently I've been using the SDR-kits cal kit (PDF doc), but have not exercised them beyond 1 GHz yet. The kit is not bad for what it is, however, the supplied 50-ohm load in my case had 48.52 ohm DC resistance. That's normally not an issue (there's another thread on the topic elsewhere) and some VNAs allow for entering that value, but if that's a concern (personally, I wanted closer to 50 ohm because I also tend to use it for various purposes at low frequencies, from DC to tens of kHz) then the very easy solution is to just replace that with your own 50-ohm load, e.g. Huber & Suhner ones are often much closer at DC.
« Last Edit: September 07, 2024, 07:13:38 pm by shabaz »
 


Offline 小太

  • Contributor
  • Posts: 18
  • Country: au
Re: Kirkby calibration kit alternatives?
« Reply #216 on: September 08, 2024, 11:10:30 am »
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?)

Sorry for the necropost.  I had watched the METAS video and they did not go into any details on how to accomplish this.  Going through this thread, I too am curious how to derive the coefficients for an unknown set.   

The last time I did this, I used one of the local members Matlab scripts. I would like to try this with METAS.  Any pointers to save my hair are appreciated.   

I just followed the instructions by alan.bain posted a bit further up:
(You have to open a measurement file first)

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!
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf