Learning Forum

[xin zhang]

I am looking at far-field radiation from a dipole source, using the top half of a box-type far-field projection monitor with a base, and I want to know: 1. Is far-field filtering required when using a box monitor? 2. How to set filtering parameters (because I found that the electric field at the edge of the display is very large, should it be filtered directly to 0) 3. In the case of many displays, the filtering parameters at this time may vary, whichever is preferred

[Guilin Sun]

The farfield filter is used to smooth the fields in the monitor in order to not use very large simulation/monitor size. But the farfield accuracy might be compromised. 

If you are using box monitors, there is no need to use such filter, since it uses

farfieldexact

method to get the farfield from all related monitors.

 

[xin zhang]

Thank you very much for your reply. Can I understand this way: If the electric field is cut off to zero inside or at the edge of the monitor by using a larger monitor, then the far-field filter function can be unnecessary. If I want to observe the far-field radiation pattern distribution of particles on the substrate (possibly SPPs waves), is a box monitor the best choice? Are there requirements for the location of the box monitor for the dipole source and distance from other structures? Hope to get your reply, thank you very much!

[xin zhang]

Can you help me? It's really important to me. Thank you so much

[Guilin Sun]

Yes, the filter is to smooth the monitor data and make sure the intensity at the monitor edges is small enough. Thus if the monitor (and simulation region) is large enough you do not need to use it.

For particle on substrate, you can try to use 5 box monitors in analysis group, or use large FDTD and monitor spans to pick up all the scattering.

https://optics.ansys.com/hc/en-us/articles/4403945613843-Polar-plot-of-scattered-field-with-particle-on-substrate 

If box monitors are in lossless material, the distance does not matter. 

 

 

[xin zhang]

Thank you again for your reply, this information is very useful to me, thank you very much!