I want to characterize an inhomogeneous slab (variable permittivity & permeability) in CST for normal and angular incidence of 'plane wave'. The way I am doing it until now is by using a rectangular waveguide, as shown in the attached image. I find this method intutive, but the simulation can become heavy if the waveguide is placed at a distance from the substrate.
Are there better ways to do it in CST? All answers appreciated.
Sincere regards.
You can do this by efining the constitutive parameters of each layer, if your model is that simple, plane wave, you could use a 2D model instead.
It depends on what you precisely want to do:
1. Is your slab completely and easily definded/modelled? E.g. is it a multilayer slab, or a "random material", or something closer to a metamaterial?
2. If this is not the issue (the slab can be modelled as desired), but a question related to its "effective" reflectivity/transmittivity properties, it depends in which condition(s) you wish to illuminate it: is it in Far Field (FF) or in NF condition? If it is in FF condition, the problem comes down to estimate equivalent Fresnel coefficients (in reflection and transmission) and one to perform that in CST is to illuinate the slab with a plane wave (considering various incidences and wave polarizations). If the slab is a multilayer one, the result can even be computed analytically (so e.g. implementable in Matlab - I have already a code for that if you like) under the hypothesis of infinite slab, or in practice for small wavelenths compared to the slab dimensions (so that diffraction can be nglected). If it is in NF conditions, it is far more complicated: it depends on the characteristics and the distance of the source, i.e. on the wavefront characteristics, and so on...
Thank you all for your answers.
Giovanni, the slab does not have periodicity, so I will not be using floquet analysis.
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