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lostarmour

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Everything posted by lostarmour

  1. Is there any way I can avoid the reflection from edges of the ground plane? Like adding a resistive load on the finite ground plane at a distance so that no energy is reflected back? If it is possible, how can I do it?
  2. Hello all, I want to implement a rectangular waveguide with a metal flange at the aperture. Intention is to see the reflection characteristic at the aperture-freespace boundary and the near field as a result of that. I wanted to know how exactly should I put my waveguide excitation so that I can only observe the aperture-freespace reflection coefficient. I also want to know how to put an infinite ground plane surrounding the aperture. For now, I am using a 5\lambda \times 5\lambda metal 2D surface. I am attaching my model to this thread. Thanks in advance. recv2_NF_MF.cfx
  3. When I choose a near field source for far field computation, I am asked to choose a configuration with either one electric field source, both electric and magnetic field sources or magnetic field sources. What is the difference. For example, if I choose only electric field source, does it evaluate far field by a equivalent magnetic source ( \vec{M} = 2 (\vec{E}_{a} \times \hat z ) ) ? Or one needs to put an infinite ground plane surrounding it (so that the source becomes a slot) and then need to simulate?
  4. I am attaching a new simulation where the port settings are good. I have one port excited with one mode and the other port is absorbing all the energy. I am attaching the cfx file (Cone_7cm_TE11.cfx) where I generate the near fields and the cfx file where I use the near fields (FF_cone_7cm_TE11.cfx) and the near field files as well. Here, I also use a metal plane around the near field source such that the source acts like a slot. Therefore, I should see radiation to both sides of the space and I still see the radiation to one half of the space. FF_cone_7cm_TE11.cfx Cone_7cm_TE11.cfx NF_cone_7cm_TE11_cart.hfe NF_cone_7cm_TE11_cart.efe
  5. Hi @mel, Did you, by any chance, check the original problem?
  6. Yes, I did that. Thanks for this input.
  7. Yes, I wanted to make the bottom port as absorbing. Therefore, I used the modes I wanted and set the excitation to 0 for those modes. In the advanced tab, it only asks for maximum m and n indices of the modes. Should I write the maximum values of m and n for the modes I consider? It doesn't say anything about TE or TM.
  8. Hi @mel, I am attaching the files here. circular_5wg_5modes_1mm_2cm_1mm_fields.cfx NF_5wg_10modes_each.efe NF_5wg_10modes_each.hfe
  9. Hi all, I wanted to understand how the far field from a near field response from another simulation works. I have a circular waveguide junction problem where I find the aperture field distribution and make it the input of the next simulation as a source to find the far field from it. I have put a PEC surface around the near field source (Not above or below) so that the near field acts as a slot (magnetic virtual current source). I expected to see radiation towards both half of the space but I see on one side like as if there is a PEC surface below that too. However, for some other configuration I do see some radiation towards the other half space. I wanted to understand what exactly happens. I am attaching both models. circular_2wg_10modes_FF_from_NF.cfx circular_5wg_10modes_FF_from_NF.cfx
  10. Hi mel, I fixed it. No problem. Sorry for the late response.
  11. For example, take this example file I am attaching. In this I have excited only one TE mode at a frequency where the only TE mode is propagating. In this case also, in spite of having a mesh size of lambda/40, I still get some z component of E field. I guess because of this, when I add more modes, the z components due to only TE modes also get added. 1wg_OnlyTEmodes_NF_V2.cfx
  12. Yes, I have all the other modes propagating as you mentioned. Therefore, I also tested when all these modes are active (excited) at the port and the result is different. And I even excited only the TM modes out of these modes and the result is again different. I have a theoretical model on MATLAB and I use z component for TE as 0 and for TM non-zero. My only TM mode simulation in FEKO matches the results of MATLAB (all modes excited). Therefore, I expected that the only TE mode excitation in FEKO should give me almost 0 z component of electric field.
  13. Hi everyone, I have been trying to simulate a waveguide junction problem with waveguide ports to calculate the field distribution on the aperture. I have a 5 circular waveguide problem where I use only TE modes at the small waveguide port. On the other end I have used a port with 0 excitation from all the modes to ensure an absorbing boundary condition. The problem is that I still get a finite z component for the aperture E field. However, from theory we know that the aperture fields for a TE mode should have a 0 z component. This I have observed in only 1 waveguide problem too. This also happens when the discretization is lambda/25. Is that a numerical artifact? I am adding the cfx file also to this thread. circular_5wg_5modes_1mm_2cm_1mm_fields_lam25_OnlyTE.cfx
  14. Thank you very much and I am looking forward to it.
  15. In this example I actually specify which modes I need and I want to study S parameter convergence by having more modes. Is there any way to do it?
  16. Hi all, I am getting an error which says "The following message from the server process (MYID= 15): ERROR 36100: Too many modes included at a circular waveguide port." I wanted to know why does that happen. Thanks!
  17. Hi all, I am getting an error which says it is an internal error. I always gets stuck at 7%. It happens with all kind of mesh sizes (Fine, Standard and Coarse). I am attaching the model here. circular_2wg.cfx
  18. Thanks for the insight. Does it have a rule for the standard mesh? Like how much it is going to reduce based on wavelength inside the medium and conductivity?
  19. Hello everyone, I have a small doubt regarding the mesh size of the FEM solver when the material inside a 3D body (for RCS consideration) is characterized with some finite conductivity. I can see the standard mesh default for FEM is around `\lambda/10` but with a conductivity of 10 inside a material (`\epislon_r = 1`), the mesh size for standard meshing is around `\lambda/145`. Does it change when the skin depth changes? I have attached my cfx here. Cyliner_FEM_V2.cfx
  20. Yes! However, the meaning of a face with a medium as layered dielectric as I showed in the question means that it is a thin dielectric sheet only?
  21. Hello everyone, I have a mode of a propeller in which I have only faces and edges. However, it is a 3D figure. When I want to make the medium of the model a dielectric medium, I get to choose between PEC, layered dielectric and default. The thing I do not understand is how can be a layered dielectric be a medium? Is it over a medium already? What exactly does it do when I select the medium as layered dielectric?
  22. Yes it is very helpful. Thanks a lot.
  23. Hello Everyone, I want to receive the RCS data of a propeller for both co and cross polarization. When I do a calculate field in the same direction on the far field as plane wave incidence, it gives me monostatic RCS. Therefore, I assume it depends on the plane wave incidence. However, in the plane wave incidence I can put one polarization for transmit and the result that I get is the co polarization (Either HH and VV). How can I receive monostatic HV and VH?
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