Waveguides - Erroneous Absorbing Boundary Conditions?
I have trouble with the waveguide ports in the straight waveguide model. My understanding is that the fields are excited by an analytical field distribution (i.e. sine half-waves), and the incoming waves are absorbed by some kind of abc. However, I am already failing to understand the result of the simulation.
With a sufficient discretization and excitation above cut-off frequency, I would expect a reflection free transmission from one port to the other. This corresponds to |s_{11}|=0=-\infty\,\mathrm{dB}
, |s_{21}|=1=0\,\mathrm{dB}
, and identical field distributions for real part and imaginary part, but shifted by 90° in space. But I witness a strong reflection of |s_{11}|=-7.3\,\mathrm{dB}
and significant differences in the field plots.
May there a bug in the abc formulation of the model?