Numerical electromagnetics
21.08.2006 21:00
Here are some nice pictures generated with a piece of software I have been working on for the previous week. This (it still needs a name - suggestions are welcome) will be a tool for numerical analysis of printed circuit boards. It is my last project as part of my undergraduate study of electronics.
Currently it can take any printed circuit board designed with PCB, calculate stray capacitances between traces and print them out in a SPICE-compatible format. As a side effect it also generates pretty pictures of electrostatic field strengths.
This picture shows the strength of the electrostatic field in a simple PCB that forms a plate capacitor: the top copper layer is grounded and the lower layer is at a fixed voltage. The vertical dimension is exaggerated.
Plates aren't shown on the picture. You can see the bottom one as a black outline against the electric field because there is no field inside the plate.
This is the result of running the simulation on a board I designed some time ago. You can see that at one point the field strength reaches around 40 kV/m. That is the point where the ground and supply trace are closest together - between the pins of the voltage regulator.
The program uses a finite difference method to calculate electric field and I believe it would be quite simple to extend it to also calculate trace resistance. It may even be possible to use it to calculate magnetic fields and inductances, however I haven't looked into that yet.
The code is a mess right now. I will put the source on-line as soon as I get things together and find some time to document things.
