I am using VNA but I have seen just a slight change in the SMA connector position change the value of frequency & S parameter. Every time reading for the same sample are different how to fix it.
Hello, I would like to mention that I did not understand very well what changes in your measurement. Nor what is the small variation that is made in the position of the sma.
But, if what you have is a problem in the measurement in terms of noise, you could do a calibration by reducing the IFBW.
Another very important point that you can check is that the number of points you take in your measurement is sufficient. I would like to be more helpful but for that a little more information is required.
Yes, it will occur. You must tighten it enough so that it gives the same reading every time.
yes its look like a badly tightened connector or a poor cable or both..or something loose in your device un der test; do the test to gently tap with the finger or some screwdriver on every element (cables connectors DUT) in your setup
Hector Morales I am trying to measure S11 with frequency on some liquid-based samples. But everyday reading is not exactly the same as previous.
Dear Andleeb,
If you are using cavity perturbation method, VNA will certainly show changed values every single second as it is highly sensitive method. You can check for any lose connection and set the resonant frequency. But once you set that, a little variation in fs values will always occur. In such case, you can either take value by changing continuous signal setting to single stimulus and repeat same for 3 sets and take average. You can also take 3-4 screenshots for varying values and average may be considered true value. It must be noted that variation should occur after 3rd or 4th decimal point of a value. A large variation every time indicates a damaged sma connector with worn out grooves.
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