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Boundary condition in 3D transient analysis of RF module
Posted 14 feb 2010, 13:29 GMT-5 6 Replies
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I am simulating a 3D waveguide geometry for observing nonlinear effects using 3D transient analysis of RF module. The problem is defining the electric field distribution at the the input boundary face of the waveguide.
In the RF model library, there is a case of gaussian beam propagation in such 3D waveguides where the input field is defined by the help of analytical expression of gaussian beams. But I have no such analytical expression for the particular guided mode that I want to simulate.
Nevertheless, I do know how the input field precisely looks like based on the results I obtained using "2D Perpendicular waves" analysis method. I am wondering if there is any way of exporting this result to "3D transient analysis" method in order to define the input field configuration? I will greatly appreciate if anyone could inform me if that is even possible or not. And in case it is, how.
Thanking in anticipation.
In the RF model library, there is a case of gaussian beam propagation in such 3D waveguides where the input field is defined by the help of analytical expression of gaussian beams. But I have no such analytical expression for the particular guided mode that I want to simulate.
Nevertheless, I do know how the input field precisely looks like based on the results I obtained using "2D Perpendicular waves" analysis method. I am wondering if there is any way of exporting this result to "3D transient analysis" method in order to define the input field configuration? I will greatly appreciate if anyone could inform me if that is even possible or not. And in case it is, how.
Thanking in anticipation.
6 Replies Last Post 31 mar 2011, 15:31 GMT-4
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Posted:
1 decade ago
Ok, I might modify the question somewhat as I have moved to Comsol's scripting environment:
I have the numerically computed field distribution which I want to inject into one of my boundaries. How can I do this?
Again, if I had an analytical formula, I could have easily done this with the following two commands:
bnd.E0 = {{0;0;0},{0;0;0},{'Ex';'Ey';'Ez'}};
bnd.ind = [1,1,3,1,1,2,3,1,1,2,2,2,2,2,1,1];
Structure bnd above is a member of xfem structure containing information about the whole problem. In the first command, strings 'Ex', 'Ey' and 'Ez' denote analytical expressions already defined in the field of boundary expressions. The second command just injects this analytical expression into the boundary parts referred to by the number 3. Comsol's solver then evaluates these values in runtime on mesh points and pump in for transient analysis.
Now, I want to replace 'Ex', 'Ey' and 'Ez' with, say, arrays whose values correspond to the numerical value of these electric field components. Can anyone give me an idea on how to do this?
I have the numerically computed field distribution which I want to inject into one of my boundaries. How can I do this?
Again, if I had an analytical formula, I could have easily done this with the following two commands:
bnd.E0 = {{0;0;0},{0;0;0},{'Ex';'Ey';'Ez'}};
bnd.ind = [1,1,3,1,1,2,3,1,1,2,2,2,2,2,1,1];
Structure bnd above is a member of xfem structure containing information about the whole problem. In the first command, strings 'Ex', 'Ey' and 'Ez' denote analytical expressions already defined in the field of boundary expressions. The second command just injects this analytical expression into the boundary parts referred to by the number 3. Comsol's solver then evaluates these values in runtime on mesh points and pump in for transient analysis.
Now, I want to replace 'Ex', 'Ey' and 'Ez' with, say, arrays whose values correspond to the numerical value of these electric field components. Can anyone give me an idea on how to do this?
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Posted:
1 decade ago
Hi, maybe you can go to Options>Functions, there you can attach a file, by choosing analytic, piecewise analytic or interpolation, you can plug your value either analytically or numerically.
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Posted:
1 decade ago
You can combine transient RF mode with boundary mode analyis by choosing RF Module>Boundary Mode analysis.
There is a similar tutorial model called 'waveguide adapter', maybe you can have a look.
I tried this previously, but I found that it is difficult to plug the numerical values of different boundaries at the same time. It seems it can only plug value from one boundary with homogeneous medium easily like what is done in the tutorial 'waveguide adapter'.
There is a similar tutorial model called 'waveguide adapter', maybe you can have a look.
I tried this previously, but I found that it is difficult to plug the numerical values of different boundaries at the same time. It seems it can only plug value from one boundary with homogeneous medium easily like what is done in the tutorial 'waveguide adapter'.
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Posted:
1 decade ago
Hi Jing,
Thank you for the response. This is an old question I had posted when I was beginning to use Comsol. Now I know how it is done and it is just the way you described.
I have not tried plugging values simultaneously from multiple boundaries but I shall be surprised if it is not possible.
Thank you for the response. This is an old question I had posted when I was beginning to use Comsol. Now I know how it is done and it is just the way you described.
I have not tried plugging values simultaneously from multiple boundaries but I shall be surprised if it is not possible.
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Posted:
1 decade ago
Hi Shakeeb and others,
I want to do time domain analysis of antenna which has to radiate gaussian short pulses (UWB).
Could you anyone advise about the boundary conditions for time domain analysis and to generate UWB pulses?
Thanks,
Kirthika,
I want to do time domain analysis of antenna which has to radiate gaussian short pulses (UWB).
Could you anyone advise about the boundary conditions for time domain analysis and to generate UWB pulses?
Thanks,
Kirthika,
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Posted:
1 decade ago
Hi,
You need scattering boundaries to excite source. Remember that scattering boundaries are not able to perfectly absorb back reflections like PMLs. And until 3.5a, I know for a fact that PMLs are not available in transient module. May be it has changed in 4.x but I didn't see it mentioned in change logs.
All the best
You need scattering boundaries to excite source. Remember that scattering boundaries are not able to perfectly absorb back reflections like PMLs. And until 3.5a, I know for a fact that PMLs are not available in transient module. May be it has changed in 4.x but I didn't see it mentioned in change logs.
All the best