negative group delay of S21
时间：04-05
整理：3721RD
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Hi all!
i made a transmission measurement (S21) with the VNA. the frequency range is 2 to 4 GHz. the DUT between the two antennas was a teflon plate. the distance between the antennas was 50 cm. I was surprised to conclude that the group delay (tau) is negative. What does mean a negative time? did i make a mistake in the measurement?
thank you all.
i made a transmission measurement (S21) with the VNA. the frequency range is 2 to 4 GHz. the DUT between the two antennas was a teflon plate. the distance between the antennas was 50 cm. I was surprised to conclude that the group delay (tau) is negative. What does mean a negative time? did i make a mistake in the measurement?
thank you all.
You did probably a calibration error.You should do this calibration with SOLT technique to get the right phase results.
How did yout setup VNA calibration? What's the transmission reference?
Negative time in group delay reflects the poor coupling in the structure. It is not a big problem. It can be corrected by making changes in the structure.
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