# Discussion Forum

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## Angle of incidence, RF modul, Comsol 4.2a

Dear All,

I have issue. I have one metal block on substrate, and I want to illuminate it but at some angle (picture).

One half sphere is substrate, one half air.

Now I want to apply x polarization, scattered field.

I have two cases, first when substrate is also air, and second when substrate is glass (with index refraction ns).

In the case when substrate is air I applied equation: E0*exp(-j*(emw.k0*x*sin(phi)+emw.k0*z*cos(phi)).

In the case when substrate is glass I applied equation: E0*exp(-j*(emw.k*x*sin(phi)+emw.k*z*cos(phi)).

Or maybe in second case I have to write:

(1-sign(z))*E0*(-j*2*pi*x*sin(phi)/Lambda-j*2*pi*z*cos(phi)/Lambda)/2 +

+ (1+sign(z))*E0*(-j*2*pi*x*sin(phi)*ns/Lambda-j*2*pi*z*cos(phi)*ns/Lambda)/2

Tell me please for any of these equations are they correct.

5 Replies Last Post Nov 18, 2012, 11:58 PM EST
Posted: 5 years ago
I want to know that you use the scattering boundary condition or the Port to input the light, and how do you set the wave direction or the propagation constant

Posted: 5 years ago

I want to know that you use the scattering boundary condition or the Port to input the light, and how do you set the wave direction or the propagation constant

I used scattering boundary condition, but I am nor sure that I understoood second question about equation.

Posted: 5 years ago
I think you can type E0*exp(-j*(emw.k0*x*sin(phi)+emw.k0*z*cos(phi)) in the "incident field", or you can just set kx=k0*sin(phi), ky=k0*cos(phi) in the "wave direction"

Posted: 5 years ago

I think you can type E0*exp(-j*(emw.k0*x*sin(phi)+emw.k0*z*cos(phi)) in the "incident field", or you can just set kx=k0*sin(phi), ky=k0*cos(phi) in the "wave direction"

Hello,

I am not sure about second way. I used first way: E0*exp(-j*(emw.k0*x*sin(phi)+emw.k0*z*cos(phi)). I always use incidetn field, not wave direction.

Cheers

Posted: 5 years ago
Hello
Do you find that if you use the same incident field for example E0*exp(-j*(emw.k0*x*sin(phi)+emw.k0*z*cos(phi)), but select the different boundary as the input, the wave direction is different, do you know why?
Cheers！

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