Dielectric-filled waveguides

[wsapia]

First off, this project is awesome, great work!

I was looking over the examples you have, and the waveguide BPF synthesizer caught my eye. I was impressed with how quickly that example ran and generated a filter. I noticed that you had an unused variable dielectric_constant = 1.0 in there, and it got me thinking about dielectric filled waveguide filters. I tried modifying your example to work with dielectrics other than air/vacuum, but I wasn't able to get it working. I went through some of your code, and I think the fundamental issue might be that your em.Simulation.mw.bc.RectangularWaveguide class doesn't seem to properly handle the calculations when the dielectric isn't air/vacuum. The get_beta function doesn't account for different values of $\epsilon$_r or $\mu$_r. I haven't been able to dig into this code completely to verify that this would solve the issue, but it seems like that might be a good place to start. I'm wondering if you have any thoughts on this.

[FennisRobert]

You are exactly right, i haven't added that feature yet. In the mean time you can use the ModalPort, that will take it into account. Ill add the dielectric constant for the next patch :)

[FennisRobert]

As an update, it has been in the new EMerge for a wee bit. I can't remember when but at least since 2.0 I think. In any case for the RectangularWaveguide class it has the er property. Which does not make much sense. The absorbing boundary condition now has the more logical material property. I'll fix it soon that also the Rectangular waveguide accepts a Material but I guess er suffices for now :)