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material measurement

Question asked by mariya001 on Oct 7, 2015
Latest reply on Oct 22, 2015 by daras

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Hello, I am using N5242A PNA-X with 001 option for material measurement with waveguide calibration kit.(X11644A ) using smart cal kit option for NA. I need to ask
1. While performing waveguide calibration, should i connect the 1/4 lambda shim for the through( defined thru) calibration or not. The delay for the standard defined thru option that come on PNA screen is ( 0mm / 0sec). If I add the shim for the thru calibration then should i change/add the value of the delay in the cal kit standards.
2. If shim is added for thru calibration, then what would be the sample holder length in the 85071E material measurement software.

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drkirkby Oct 7, 2015 11:59 AM
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> {quote:title=mariya001 wrote:}{quote}
> Hello, I am using N5242A PNA-X with 001 option for material measurement with waveguide calibration kit.(X11644A ) using smart cal kit option for NA. I need to ask
> 1. While performing waveguide calibration, should i connect the 1/4 lambda shim for the through( defined thru) calibration or not. The delay for the standard defined thru option that come on PNA screen is ( 0mm / 0sec). If I add the shim for the thru calibration then should i change/add the value of the delay in the cal kit standards.

I don't know the PNA-X menus, but for a normal waveguide calibration kit, to perform a 2-port cal, you only need a

* Flush short on port 1
* Quarter wave offset short on port 1 (which in the X11644A you get combining the quarter wave shim and the short)
* Load on port 1
* Flush short on port 2
* Quarter wave offset short on port 2 (which in the X11644A you get combining the quater wave shim and the short)
* Load on port 2
* *Zero length thru.*

If the PNA is telling you a zero delay thru, then I would do as it says, as that is what I would expect. It is what I always do when doing a waveguide calibration. In fact, I have built waveguide cal kits for others, and say they should do that.

The X11644A comes with a precision section of waveguide. The manual tells you to how to verify the calibration by adding that, and putting a short on the end. Then see what the maximum ripple is.

> 2. If shim is added for thru calibration, then what would be the sample holder length in the 85071E material measurement software.

I very much doubt you need the shim. So I would have thought your sample length was just whatever you put between the waveguide flanges.

Note,
1) I don't work for Keysight
2) I don't have a PNA-X
3) I don't have the materials measurement software.

All my suggestions are based on what I know from calibration of much older analyzers.

Dave

Edited by: drkirkby on Oct 7, 2015 6:57 PM
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mariya001 Oct 8, 2015 6:28 AM
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Thankyou so much. Can anyone from agilent help me in clearing the confusion regarding the use of 85071E material measurement software using the waveguide setup. In the measurement setup, the 4th option ( Poly Fit ) in the measurement models states that the position of the sample should be exactly known. There is a provision of providing distance of the sample from the first port of calibration, if it is not placed exactly at the calibration plane. But what about distance of the sample from the port 2? If the sample thickness is same as that of 1/4 lambda shim then the sample is placed exactly at the calibration planes from both ports. What if the sample thickness is smaller than the shim or the sample holder how we cater that in 85071E software.

Also how to we determine that the time domain gating doesnot remove responses from the material under test and only removes responses from the system.
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mariya001 Oct 9, 2015 9:17 AM
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Waiting for the reply please...anyone who can guide me
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- drkirkby @ mariya001 on Oct 10, 2015 10:27 AM
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  to be migrated, sourceId: 122045
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  - straight-section-00896-60007-from-P11644A.jpg483.2 KB
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mariya001 Oct 12, 2015 9:52 AM
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Thankyou so much Mr .Dave for your kind reply. I have yet to hear from Agilent. Can you kindly guide me how to setup hp8510c for waveguide calibration and measurements. How to setup the calibration coefficients if I do not have any standard Agilent and Maury etc wg kit. I have two equal wg sections., a load , a flush short, a shim 39.5mm deep and 52 mm offset short. How to measure the calibration coefficients ,store them, apply time domain gating for the sample to be measured for s11 and s21 placed at the shim location.

So this is how the setup will look like with sample in place
VNA Port1 - coaxial cable- wg section - lambda/4 shim- wg sec- coax cable- VNA port 2
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- mariya001 @ mariya001 on Oct 14, 2015 7:45 AM
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  Waiting for the reply please
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  - daras @ mariya001 on Oct 14, 2015 11:37 AM
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    Hi Mariya,
    
    Our materials measurement expert is currently out on vacation and won't be back until 10/16. I've have alerted him to your question and hopefully he'll be able to provide an answer once he has returned.
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  - daras @ mariya001 on Oct 22, 2015 9:28 AM
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    I've sent you a private message with the email address of the person you should contact directly.
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- drkirkby @ mariya001 on Oct 14, 2015 2:25 PM
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  > {quote:title=mariya001 wrote:}{quote}
  > Thankyou so much Mr .Dave for your kind reply. I have yet to hear from Agilent. Can you kindly guide me how to setup hp8510c for waveguide calibration and measurements. How to setup the calibration coefficients if I do not have any standard Agilent and Maury etc wg kit. I have two equal wg sections., a load , a flush short, a shim 39.5mm deep and 52 mm offset short. How to measure the calibration coefficients ,store them, apply time domain gating for the sample to be measured for s11 and s21 placed at the shim location.
  >
  > So this is how the setup will look like with sample in place
  > VNA Port1 - coaxial cable- wg section - lambda/4 shim- wg sec- coax cable- VNA port 2
  
  Hi,
  daras has said the materials specialist will respond to you, so hopefully that will sort out your issues.
  
  But I can tell you that to set up a waveguide calibration kit on an 8510 you can use the Cal Kit Manager 2.1 software
  
  Those thicknesses you have are *well* away from what is needed. You can't use any random thicknesses for calibration. You need two shorts which differ in electrical length by as close to λ/4 as possible, so that the difference of the phase on reflection is as close to 180° as possible; The calculation of that thickness is not quite as simple as it may seem, as the waveguide wavelength does not follow the simple equation of λ=c/f, but the waveguide wavelength is longer than the wavelength in free space.
  
  I calculate, that assuming vacuum, a shim thickness of 9.715 mm is optimal for WR90. The thickness should be a little less for air. I note the X11644A comes with a shim that is 9.78 mm thick, so I'm not quite sure how HP/Agilent/Keysight got 9.78 mm, but we both are within a few hundredths of a mm. (It may be an error in my calculation). Your two shims are miles apart.
  
  If you don't care for the exact frequency you use, then you *may* be able to find a frequency where your shorts differ by close to λ/4, but calibration is only going to work over a narrow range of frequencies.
  
  You are not going to get any sensible results until you calibrate your VNA properly, and I don't think shorts or shims of 39.5mm or 52 mm are going to be any use to you, except perhaps over a very narrow frequency range. You need to get a shim, or better still an offset short of around 9.7 mm.
  
  Dave
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mariya001 Oct 21, 2015 11:50 AM
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still to hear from keysight... Mr. Dave what are your suggestions on using one flush short and instead of using lambda/4 short for waveguides what if we use 3*lamda/8 short as an offset short... can we skip lamda/4 short ? how does it effect the measurements?
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- drkirkby @ mariya001 on Oct 21, 2015 1:43 PM
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  > {quote:title=mariya001 wrote:}{quote}
  > still to hear from keysight...
  
  Shame that, as you need their help on the materials measurement
  
  > Mr. Dave what are your suggestions on using one flush short and instead of using lambda/4 short for waveguides what if we use 3*lamda/8 short as an offset short... can we skip lamda/4 short ? how does it effect the measurements?
  
  You seem to be talking about two quite different systems, which makes it confusing.
  
  * N5242A PNA-X with 001 option for material measurement and a X11644A waveguide calibration kit
  * 8510C, with some shims and/or offset shorts of 39.5mm and 52 mm.
  
  The first of these, using the PNA + X11644A should allow for the calibration of the waveguide. The second, the 8510C with some totally bizarre lengths will not work.
  
  There two obvious ways of calibrating a VNA for use with waveguide
  
  * Flush short, λ/4 offset short and load
  * λ/8 offset short, 3λ/8 offset short and load.
  
  Either will work. The X11644A uses the first of these, whereas in a Maury Microwave X7005E, which coincidentally I happen to be selling on eBay uses a λ/8 and 3λ/8 offset shorts. I just checked the depth in my Maury kit, and the λ/8 offset short is 4.83 mm and 3λ/8 offset short = 14.48 mm.
  
  So you have two choices for the depth of the shorts.
  * 0 mm and 9.78 mm (Keysight X11644A)
  * 4.83 mm and 14.48 mm (Maury Microwave X7005E)
  
  Either will work. There is some theoretical advantages in the λ/8 offset and 3λ/8 offset shorts in that the connection is made at a low-current point, rather than a high current point in the X11644A.
  
  So in summary,
  
  * Calibrating your N5242A PNA-X with the the X11644A *will work ok.*
  * Trying to calibrate your 8510C with shorts of 39.5mm and 52 mm is *not going to work*.
  * If you want to calibrate your 8510C, then either use an Agilent X11644A, a Maury Microwave X7005E, or some other decent waveguide calibration kit.
  
  Theoretically at least, the λ/8 offset short, 3λ/8 offset short and sliding load of the Maury X7005E is better than the X11644A, but in practice, it probably does not make a lot of difference.
  
  You still never answered my question about what is your sample holder for the materials measurement.
  
  If you want help from someone at Keysight, it would be worth stating *exactly* what you have and what you want to achieve. Your original question seemed reasonably clear, but once you started mentioning the 8510C with the bits you had with that, it all gets very confusing.
  
  Dave
  
  Dave
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