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Electromagnetic propagation of a oblique incident plane wave

Posted Mar 12, 2012, 4:09 p.m. EDT RF & Microwave Engineering Version 3.5a 3 Replies

Marcos Soldera
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Hi, I am modeling electromagnetic propagation through periodic V-shaped multilayer (2D). On top I have a PML followed by an air layer where radiation enters through a port and propagates through the V-shaped multilayer where it gets reflected or absorbed (depending on wavelength). The goal of this structure is to maximize absorption due to multiple reflections between the V branches. When the radiation strikes normally, i.e. parallel to the V-axis, I get fine results. Problems begin when I try to tilt the angle of incidence (theta). I solve for total field TE waves and I use Floquet boundary conditions for the left and right sides, defining the pair (kx,ky) according to Snell's law. However, I am not sure wether this approach is right, because I don't know if it is possible to define a single pair (kx,ky) for the Floquet BCs. Should I use another side BCs instead of Floquet?

Thanks.
3 Replies Last Post Mar 12, 2012, 5:00 p.m. EDT
Alexander Kuznetsov
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Posted: 1 decade ago Mar 12, 2012, 4:29 p.m. EDT
The approach you described is perfectly fine. It's enough to use Floquet BCs everywhere on periodic BCs with kx and ky defined for air.
The approach you described is perfectly fine. It's enough to use Floquet BCs everywhere on periodic BCs with kx and ky defined for air.
Marcos Soldera
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Posted: 1 decade ago Mar 12, 2012, 4:46 p.m. EDT
Hi Alexander, sorry I don`t understand well your explanation. When you say "...Floquet BCs everywhere on periodic BCs with kx and ky defined for air" do you mean kx and ky defined for the incident wave after it propagates (and thus refracts) through the materials? or just kx=k0_rfwe*sin(theta) and ky=k0_rfwe*cos(theta)? I currently calculate each kx and ky for each single layer with Snell´s law, but I fear that the remaining k-vectors (the ones produced by the multiple reflections) cannot be handled by the floquet BCs.

By the way, do you recommend any bibliography or tutorial where I could understand better the fundamentals of floquet BCs?
Kind Regards.
Hi Alexander, sorry I don`t understand well your explanation. When you say "...Floquet BCs everywhere on periodic BCs with kx and ky defined for air" do you mean kx and ky defined for the incident wave after it propagates (and thus refracts) through the materials? or just kx=k0_rfwe*sin(theta) and ky=k0_rfwe*cos(theta)? I currently calculate each kx and ky for each single layer with Snell´s law, but I fear that the remaining k-vectors (the ones produced by the multiple reflections) cannot be handled by the floquet BCs. By the way, do you recommend any bibliography or tutorial where I could understand better the fundamentals of floquet BCs? Kind Regards.
Alexander Kuznetsov
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Posted: 1 decade ago Mar 12, 2012, 5:00 p.m. EDT
This way is correct:
just kx=k0_rfwe*sin(theta) and ky=k0_rfwe*cos(theta)


If you calculate kx and ky for any other layer, it is the same due to Snell's law. You can read more about Floquet BCs here (open the pdf) www.comsol.com/support/knowledgebase/1115/


This way is correct: [QUOTE]just kx=k0_rfwe*sin(theta) and ky=k0_rfwe*cos(theta) [/QUOTE] If you calculate kx and ky for any other layer, it is the same due to Snell's law. You can read more about Floquet BCs here (open the pdf) http://www.comsol.com/support/knowledgebase/1115/

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