Thread: How to shift the measurement plane of to the device plane

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Permlink Replies: 3 - Pages: 1 - Last Post: Jun 28, 2012 12:52 PM Last Post By: Dr_joel
mtxx

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Registered: 03/28/12
How to shift the measurement plane of to the device plane
Posted: Mar 28, 2012 9:55 PM
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Attachment untitled.PNG (21.5 KB)
Good day to everyone.

This is my first post and i greatly need your help.
For my project, i would like to measure the S11 and S21 of a DUT.
my DUT, are various thin pieces of material, approximately 2x2cm, and 0.1cm thick will be sandwich between two rectangular waveguides.

i have 2 VNA at my disposal.
1. Agilent E5070B
2. Advantest R3767CG.

In order to measure the S11 and S21 of ONLY the DUT (excluding the waveguides)
i need to shift the measurement plane to the device plane.
as shown in the attached picture.

I've done lots of reading in google, and the googled results are not detail and satisfactory, or maybe they are too advance for my understanding.

According to an application note by Rohde& Schwarz on "measurement of dielectric material propertiess", this can be done by
-adjusting the electrical length or
-using the de-embedding function present in most vna.

I cant find anything about "de-embedding" feature in the manual of my both vna, but i found out that i have the electrical delay function. Sadly, i have no idea how to calculate the delay required.

How can i calculate the required electrical length correction to exclude the effects of the waveguides?
Please help me, any help will be deeply appreciated.
Dr_joel


Posts: 2,371
Registered: 12/01/05
Re: How to shift the measurement plane of to the device plane
Posted: Mar 29, 2012 11:17 PM   in response to: mtxx in response to: mtxx
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I agree, R&S and Advantest are pretty worthless when it comes to helping out (oh, did I say that? Sorry, I immediately apologize). what you need is a way to automatically extend the ports' electrical reference plane to the reference plane of the Device Under Test (DUT).

Fortunately, there is a brilliant new method in the ENA (and PNA) called "Automatic Port Extension" that does exactly that.

Here's a link to the basic brochure: http://cp.literature.agilent.com/litweb/pdf/5988-3765EN.pdf

Here's a link to more info on port extensions (based on the PNA, but the information is relavent to any VNA): http://na.tm.agilent.com/pna/help/latest/S3_Cals/Port_Extensions.htm
Here's another link for more details:
http://mwrf.com/Articles/Index.cfm?ArticleID=18931&pg=2
And here's a link with all the details
http://www.google.com/patents/US7088087

Hope it helps.
mtxx

Posts: 7
Registered: 03/28/12
Re: How to shift the measurement plane of to the device plane
Posted: Jun 23, 2012 5:59 AM   in response to: Dr_joel in response to: Dr_joel
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Before i do port extention, i need to do calibration first right?

The VNA i'm using is fairly old, a E5070B 300k-3GHz
where can i find the instructions for this model?

i do not have ecal or calibration standards for this model.
can i define myself using TRL calibration?

can i short my fixture as thru, leave it open as reflect, and connect a random item between as line,
and the vna will auto cal for me. is it that simple? or are there additional steps involved?

in your brochure link,
http://cp.literature.agilent.com/litweb/pdf/5988-3765EN.pdf
it mention about a calibration wizard, but i cant find a way to start it. where can i launch it?

edit:
i found this guide http://www.icmicrowave.com/pdf/ENA_Multiport_TRL_LRM_manual.pdf
i've downloaded and installed the program described inside.
after running it, i need to input the details of my TRL standards manually. this is akward, i thought i am able to measure the standards directly, i do not know the delays of each my standards

Edited by: mtxx on Jun 23, 2012 6:37 AM

Edited by: mtxx on Jun 23, 2012 6:48 AM
Dr_joel


Posts: 2,371
Registered: 12/01/05
Re: How to shift the measurement plane of to the device plane
Posted: Jun 28, 2012 12:52 PM   in response to: mtxx in response to: mtxx
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I don't remember if older model ENA-B support TRL as native mode or as a VBA, but if you have TRL support, and you are using waveguide, it is very easy to get a cal kit.

1) use short as the reflect (R in TRL)
2) use a thru (direct connection) as the T in TRL
3) use a 1/4 shim (waveguide whose length is about 1/2 the widest dimension of the waveguide) as the line.

Do this at the waveguide intefact to your DUT and you don't need to do any port extension or de-embedding.
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