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Farfarfield 3D integration


    • sagar
      res = 201;
      E2 = farfield3d(m,1,res,res);
      ux = farfieldux(m,1,res,res);
      uy = farfielduy(m,1,res,res);
      cone_30 = farfield3dintegrate(E2, ux, uy, halfangle, theta0, phi0); # integrate over 30 degree cone
      total = farfield3dintegrate(E2, ux, uy); # integrate over entire hemisphere
      T   = transmission(m); # fraction of source power transmitted into far field 
      ?cone_30/total;  # fraction of far field power within a 30 degree cone
      ?cone_30/total*T; # fraction of source power transmitted into the far field within a 30 degree cone

      Can you explain this code. I want to calculate the collection efficiency from my structures. I am getting error
      in line 9, "farfield3dintegrate(A,ux,uy), A muat be an NxM or NxMxP matrix, with length length(ux)=N,length(uy(=N, N>2and M>=2".
      I thing they are matrix and could not figure out the meaning of this error msg.


    • Guilin Sun
      Ansys Employee

      I tested your script and did not find anything wrong:

      Please make sure that your file is 3D and no ay error massage shows before line 9.


      The error message showig from above means the matrix has something wrong. Please check the dimension of E2.

      You may also need to reboot your computer, modify the simulation settings if necessay, redo the simulation and run the script.


    • sagar

      Actually I want to calculate the collection efficiency from this 3D far-field profile, how much light is going toward the forward direction. Can you suggest how to do this?

    • Manuel Reza

      I use the same conversation to submit my question as well, because it is very relevant. 

      The script does work indeed, but there is a serious limitation. How should I integrate over a different range of angles? Not a circular cone, but an elliptical cone for example.


    • Guilin Sun
      Ansys Employee

      Unfortunately this integration script works only for a circular cone. You can file a feature request for ellipitical cone.

      "how much light is going toward the forward direction. Can you suggest how to do this?"  a plane monitor can only collect power forward (transmission) or backward (reflection). the total power is the transmission amount.

      From your result image it seems you used only a few farfield points, which may not give you accurate result. Iwould suggest to use the default value without specifying coarse farfield points.

    • sagar

      I used the default vaule given in "ff_radiation_plot" analysis group. N theta and N phi are both set as 25. Should I increase it more? 

       You made this comment earlier "A plane monitor can only collect power forward (transmission) or backward (reflection). the total power is the transmission amount.", only forward and backward monitors will not give the total power. As it is a dipole, it will radiate other directions also. And the placement if forward and backward monitor will be related to some collection angle and to collect the maximum information (High numerical aperture (NA)), I need to place a monitor in the near field.

      But the better option would be If I am able to integrate the whole 3D far filed profile and the upper part of the profile. The ratio of it would be the collection amount in forward direction. The ration would be independent of the collection angle. Can you please suggest how to do this integration? 

    • Guilin Sun
      Ansys Employee

      "ff_radiation_plot" analysis group has converted the rectilinear dataset in FDTD to unstructured data for display of 3D radiation, and I did not find any simple script command to do the angular integration, other than

      The output of the dataset Efar does not have ux,uy and uz associated.

      You can modify the script inside the analysis group, and do only forward projection, with given ux,uy and uz and convert them to theta and phi, and then get the xyz on the 1m semishere. After projection the result should be a function of ux and uy, and then you can follow the regular farfield integration.




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