I have a planar air core (no ferrite) transformer in a PCB. I need to characterize the transfer function of this transformer from DC to 500 MHz using a vector network analyser (VNA).
My first question is regarding measurement method selection: I’ve used a VNA before to characterize coils and capacitors so: first I would check the expected inductance or capacitance of this device under test (DUT) in a diagram like the one below, then I would use the measurement method with the best accuracy for the given frequency range.
Now my first question is, how to select the measurement method in the case of a transformer?
My second question is regarding the smallest signals that can possibly be measured with the VNA: I am afraid that if the voltage or current in the secondary are too small then the VNA won’t be able to measure them. My problem here is that no matter how I connect the transformer, one quantity (voltage or current) will be smaller than the primary, but as far as I know VNAs work with power (S parameters) measurements, so I don’t know how to decide (I’m dealing with a transformer with a very large ratio). How to determine what is the smallest signal the VNA will be able to measure?
Many thanks in advance!