far field emission power density using stacksolver

    • ejlee0911


      I use the stacksolver for calculating far-field emission power density with stackpurcell script command (

      I have a question about this simulation.

      I found the unit of far-field emission power density is [W/(m^2*sr)] and Prad/Po . If I regard the field as something calculated on a hemispherical surface located 1m away and 1sterdian is constant, would it be okay I treat (power density)^2 as the far-field intensity? Or there is any other way to check the far-field emission power (stackdipole-radiance result)?

      Thanks for your help.

    • ejlee0911
      I want to edit my question.

      I have misunderstood the physical mean of far-field emission power density.

      I think the physical mean of far-field emission power density may be radiant intensity per unit area, is it right?
      So how can I get the radiant flux [W] or irradiance [W/m^2] which can get from FDTD as a result of far-field |E2|?
      Can I obtain the irradiance by multiplying 2¤Ç (only consider irradiance in the upward direction) to far-field emission power density?

      I appreciate your reply in advance.

    • Guilin Sun
      Ansys Employee
      According to the article:
      Attributes: upward, downward, upward_into_air, downward_into_air. This is the power density per steradian by far field emission angle
      it is [W/sr)]. To get the total power, you simply integrate on the solid angle from 0 to 90 deg.
      Since it is not uniform, you cannot simply multiply 2pi.
      Please note that in photometry, there are different physical quantities with different units. irradiance is not power or intensity, it is power density per meter square. Please refer some literature. Here is a wiki link

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