![]() On an SNA you can come a long way with simple normalisation. One of the most important and critical things for a VNA is calibration. You need phase info to see if something is capacitive or inductive (and you can calculate all kind of info from that) things that are impossible to do on a scalar analyser. So without phase info you are not sure is there is resonance and what is the exact frequency. At the resonant frequency the fase jumps 180 degrees. This is important but the why is a bit much to write in one post. So the measured fase difference is only caused by the DUT. That gives the real attenuation and fase difference both at the same time. A VNA measures the sourced signal direct at the source and at the same time the result after the DUT. I sources a signal and measures the insertion loss (the attenuation) There is some delay between the sourcing and measurement. A soldermask is part of the transmission line but has more loss as air and is not so easy to control over a wide bandwidth. ![]() Everything in between, nearby or above it makes part of the line.A transmission line has a constant impedance. There has to be two "traces" one of them the groundplane, the other the trace. A trace is just a trace for DC but not for RF. The soldermask has to do with transmission lines.
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