I offer to share with you a TUTORIAL but don't know how to get it into your hands.
The TUTORIAL is about 15kB, zipped, and describes the step-by-step process of using FREE femm 4.2 to analyze a simple PCB structure to calculate values to then use in circuit simulation, LTspice/PSpice. The sequence can be modified for use in analyzing really complex structures, structures where there are NO formulas. [I know there are many formulas and online calculators for 'normal' structures that can provide similar values, BUT they deprive you of gaining any understanding.]
The simple structure in this example is a 50 ohm microstrip implemented using 1 oz copper on a four layer 1 inch wide 5 inch long FR4 PCB operating at 10MHz. The trace is 16 mils wide, copper 1.4 mils thick, and dielectric separations of 9 mils each with the overall PCB thickness approx 32 mils. The stack up is: Layer 1 Trace Layer 2 GND Layer 3 Vcc Layer 4 Trace
An exmaple, of gaining insight:
If the microstrip uses only the top two layers, evrything is 'normal' and as expected. Current flows into the SIGANL trace and is RETURNed through the GND plane. Of course no one would do that, you would always keep the next layer, Vcc, and use it as a pseudo-ground plane.
BUT! Now something very interesting happens. The RETURN current splits between GND plane and Vcc plane, where the current in GND plane is in the correct direction, but slightly MORE than what you put intn SIGNAL! and there is a slight bit of that 'extra' current flowing in the Vcc plane, BUT IN THE SAME DIRECTION AS THE SIGNAL??!!
No book formula I've ever found will show you this, so there is 'education' in getting down into details.
As I said, this is a step-by-step tutorial, with descriptions, explanations, and dedicated femm drawings for each step culminating in LTspice schematics of the final model. Hopefully, educational/useful for someone out there.
Regards, Robert