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Differential measurement with baluns - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


 Post subject: Differential measurement with baluns
Posted: Tue Jun 17, 2008 5:55 pm 
 
Captain

Joined: Mon Jun 19, 2006 10:27 am
Posts: 13
Hello,

I have to make measurements on differential devices with a network analyzer, for which I purchased two Baluns from Minicircuits (ZFSCJ-2-1, SMA).
How do I have to carry out the calibration on the VNA ?
open is open
short is simply a connection between the two inner conductors of the two outputs of each balun ?
match would be a 50 Ohm resistor mounted on each output or do I have do connect the two inner conductors with each other with a 100 Ohm resistor between them ?

Frequency range is 1 MHz - 500 MHz.

P.S.: Please don`t tell me that measurements with baluns are a piece of !"§$%&(/%$?, I talked about this topic with my boss, but we just have got an old VNA and we don`t have got the money for a new one with differential capabilities.

P.P.S.: I also know that there doesn`t exist anything like a `real` calibration standard for differential measurements, but I talked about this with my boss and ... you know the rest of the story, don`t you ?


 
   
 
 Post subject: Re: Differential measurement with baluns
Posted: Wed Jun 18, 2008 5:05 pm 
Actually...
open is open
short is short
and load is the characteristic impedance of your VNA


 
  
 
 Post subject:
Posted: Fri Jul 25, 2008 7:02 am 
 
Captain

Joined: Mon May 05, 2008 9:56 am
Posts: 17
Location: France
Hi all,

My question is pratically the same.
I would like to measure a differential Low-Pass filter with a VNA.

I have seen some subjects with S parameters transformations or something like that but i have not found procedures on how use the VNA for this measures.

Does anyone have an idea ?

guillaume


 
   
 
 Post subject:
Posted: Sun Aug 10, 2008 10:05 am 
 
Lieutenant

Joined: Sun Jul 27, 2008 10:29 am
Posts: 1
You can read the R&S application note

1EZ53: Measuring Balanced Components with Vector Network Analyzer ZVB

http://www2.rohde-schwarz.com/en/produc ... |-904.html

More important one is you must define the correct differential impedance in the port configuration of VNA.

gui076 wrote:
Hi all,

My question is pratically the same.
I would like to measure a differential Low-Pass filter with a VNA.

I have seen some subjects with S parameters transformations or something like that but i have not found procedures on how use the VNA for this measures.

Does anyone have an idea ?

guillaume


 
   
 
 Post subject:
Posted: Tue Dec 16, 2008 4:24 am 
 
Captain
User avatar

Joined: Fri Nov 02, 2007 3:45 am
Posts: 10
Location: germany
Hi,
just a simple coment -
don't know if it helps but
think about it

can't you use two baluns of the same kind,
measure them back to back and calibrate them into your
network analyzer setup -
now connect your filter or whatever in between and measure your response etc.

mac

_________________
regards
mac




Posted  11/12/2012
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