hertz said:Hi,
I am trying to construct the dispersion diagram of Sievenpiper's structure by using an eigensolver in HFSS. Basically, I have a unit cell of his structure. I have PML, which is situated at about 5-6times the height of the structure. I define master/slave boundary on the sides.
I get reasonable agreements with his results between the light lines in his paper. However, when the wave vector is very close to Gamma of the Brillouin zone, there is a lot of loss. Basically, my imaginary frequency is very high in the solutions at these points.
Anybody uses HFSS to construct dispersion diagram? I am not sure how to use the PML boundaries here. Please help.
Thanks in advance!
savedadogs said:What should I set the convergence to and how many modes should I solve for? Also should I regenerate the mesh for each eigen-point or can I use the same mesh? Also what does converge on real-frequency only do? Shouldnt it alwasy be real?
sassyboy said:Eigenvalues are presented as real and imaginary values. Therefore one can converge on only the real part if the option is enabled. Eignenvalues shouldn't be just real.
huilailiu said:does anybody konw the method of simulating this dispersioin digram with CST.
huilailiu said:Thanks. But the problem is what kind of boundary shall i set in Zmax? H=0 boudary or E=0 boundary.What is the physical explanation of this boudrary definition ?
Many thanks.
Added after 7 minutes:
If your solver supports an open boundary condition (which I believe HFSS does), then that would be preferable...and its physical interpretation is rather obvious. If you're restricted to a PMC or PEC boundary condition (whick I recall is the restriction in MWS), then the mode results that are above the light line will be influenced by whatever boundary you select. It should be noted that for determining the surface current bandgap, only modes that are below the light line are considered.
My thinking is that these modes (the ones above the light line...) are the same surface current modes that, in the case of an open boundary solution would either radiate off the structure (in the case of the TE modes that are above the first bandgap freq. range) or be bound to the light line (in the case of the TM modes that are below the first bandgap freq. range). Refer to Sievenpiper's seminal paper...
Care should be taken that sufficient distance be included between the Zmax of the solution space and the max Z dimension of the structure, to avoid and direct impedance loading of the structure.
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