line transmission simulation soft

I'm wondering if anyone has done an EM simulation of charged, switched transmission lines as pulse generators (e.g., a folded blumlein), and if so, which software did you use?

I'm thinking Aplac might work (supposedly it has a built-in FDTD simulator), but I've never used Aplac, so I don't know about its suitability for this purpose.

Regards,
Joe

This is an interesting problem. To know the initial DC charge you have to know the capacitance which most frequency domain EM simulators cannot provide at 0 Hz. Are you using planar transmission lines or this coax (2.5D EM simulator vs 3D)? I can try this in Microwave Office since it has HSPICE and will map frequency domain EM results into time domain using various methods.

Also, I wonder if the coax line models in linear simulators acutally sum up the full capacitance of the line, rather then just a capacitance per unit length. Interesting problem.

I've looked into it some more, and apparently xfdtd has a built in LaPlace static field solver, and is capable of simulating this kind of problem.

In looking at the reference manual, conductors within the problem space can be set to initial voltages other than zero. And timed switches can be used which can change states at any time point during the simulation.

So it seems xfdtd may be uniquely suited for this kind of problem.

I wonder if any other time domain EM simulators have these features?