"HelloI'm using N5230A and 85052B cal kitHow to understand is my sliding load working proper?"
"ThanksWhat is typical value of sliding load reflection?"
"Thank You very machIt seems to be i have sliding load explanationI have implemented two port calibration with sliding load mentioned above.And have measured broad band loads (kit 85052B).Result is in attached jpg There is a step on loads reflections. What is possible explanation?Thanks in advance."
"There is a step on loads reflections. What is possible explanation?"
""There is a step on loads reflections. What is possible explanation?"I think the step seen in your picture is an artifact caused by the instrument, not by the load itself. When you do a calibration, the algorithm supposes implicitly that the load is perfect, that is, has no reflection. This explains why after calibration the return loss for the standard load appears to be as low as -80 dB, even when the REAL return loss is -50 dB, for example. The displayed return loss (S11 and S22) after calibration is not REAL, it is only "noise", a residue that remains after calibration. These residual return loss depends on the sensitivity of the receiver used in the VNA. The jumps seen in the display suggest that your instrument has a change in sensitivity at 3 GHz. Probably, the receiver uses direct mixing below 3 GHz, and harmonic mixing above 3 GHz."
" No, the jump is actually at the frequency where the cal algorithm changes from using the fixed load (below), to using the sliding load (above)."
"Please go look at the second response, by daveb. Here he explains that the load element in the sliding load is intentionally designed to not be ideal, but to be around 26 dB return loss. This is so that as it slides, it transcribes a circle, rather than appearing as a noisy dot. Having a higer reflection will result in a better guess at the circle which is obtained by moving the load along the precision airline. It is the airline that provides the accuracy, not the load."
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