VNA fixture for measuring Zcm of a common mode choke – coax wound discussed issues with common ham practice for measuring coax wound common mode chokes.
The article left readers with some homework:
- Does the same thing occur if the core is wound with twisted pair that is well represented as a uniform two wire transmission line?
- Are the resistors beneficial?
- Do they degrade fixture behavior?
- Then, why are the used so often?
This article addresses those questions.
Does the same thing occur if the core is wound with twisted pair that is well represented as a uniform two wire transmission line?
Let’s treat the common mode choke as a black box with two input terminals at left and two output terminals at right with voltages as annotated above. Continue reading VNA fixture for measuring Zcm of a common mode choke – twisted pair wound