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Measuring High Value of Q on the Waveguides

Question asked by AndrewIsaverdian on May 18, 2007
Latest reply on May 21, 2007 by AndrewIsaverdian

We conduct measurements on multi-cavity waveguides with internal Q (Q0) around 13000 - 16000 (f0= 2856 MHz, Delta F around 170 kHz- 250 kHz)

Let say we use calibrated S11 and Smith Chart to do this.

I have noticed that new PNA such as N5230A and similar give us Q0 always about 17%-20% higher than old HP 8573 or 8510 ( we tested 3 new PNAs and three old HP anylyzers)

Mathematically Q0 is consistently higher on the PNA because the width of the peak is consistently narrower compared to old HP.

I have tried different IF settings on the N5230A, step mode, etc., it does not make much difference.

Is this due to better peak "resolution" on new PNAs ? Is the spectrum convolution on old HP analyzers is larger compared to new PNA?