Discussion Forum

I am trying to trace a particular eigenmode of a structure (e.g. a waveguide) whilst changing some parameter (e.g. wavelength, or the dimensions of the waveguide). I am using "Mode Analysis" study. Parametric sweep can do this, but there is a problem here: the structure generally supports several modes, and sometimes the corresponding eigenvalues (propagation constants) can be densely packed. if I ask Comsol to find just one particular mode, in the parametric sweep Comsol can randomly switch to any other mode. If I ask it to find a certain number of modes, it may trace the desired mode eventually, however the order of output modes can again change randomly. Basically, each time after the parametric sweep I need to check manually profiles of different modes to figure out which is the one I need and try to trace it.

I was wondering if there is a smarter way to do it? If, for instance, I use Livelink for Matlab, at each step of the parametric sweep I can update the trial eigenvalue (i.e. "Search for mode around.." field in the study options). This still does not help, however. Ideally, I need to feed each time not only the eigenvalue, but also the eigenvector from the previous step. I found some study options like "Initial values of variables solved for"... but I am not sure if this is what I need and how to use it properly.

Any advise would be highly appreciated!

PS I am using the "Wave optics" module, for some reason the corresponding tag is missing here. But RF module is similar anyway