AnsweredAssumed Answered

Overlapping frequencies in TRL calibration

Question asked by cmwong on Dec 28, 2011
Latest reply on Dec 29, 2011 by Dr_joel
Hi,

I have designed an in-fixture TRL calibration standards on PCB using FR4 material. The tranmission medium is microstrip.

During the design phase, I have assumed a dielectric constant of 3.6 for designing the 3 TRL lines with bandwidth ratio of 5:

Line1: 200MHz to 1000MHz
Line2: 1000MHz to 5000MHz
Line3: 5000MHz to 25000MHz

I am concerned with the actual fabricated PCBs that may result in a variation in dielectric constant like 3.6 +/- 5%.

I understand that in theory the variations will result in overlapping frequencies between the Lines or might have missing frequency points.

1) May I know if overlapping frequency will affect the accuracy of the TRL calibration?
2) Can I still proceed to enter my cal kit with the frequency range as mentioned above for my 3 Lines if there is variations in dielectric constant?
3) How do I check the quality of TRL calibration to ensure accurate measurement? Will re-measure the Lines and Reflect standards be sufficient?

Any advice is very much needed.

Thanks very much in advance.  

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