Device characterization

I need to check if my VHF JFET's characteristics is up to the manufacturer's specs or not. I did Id vs Vgs plot, which was easy to do. However, I am not able to think of a circuit/formula that can help me plot the (a) Junction capacitance/transconductance vs Vgs, (b) output conductance vs. Id and (c) output admittance vs Id.

I hope you guys can suggest me some idea.

Taking 'S' parameters with a network analyser is the typical practice. S parameters can be converted to any other model, Y parameters, Z parameters, hybrid pi, etc.

This is how semiconductor models are developed for I.C. design work. There is also a process to de-embed the measurement vehicle parasitics to get to a raw model.