Learning Forum

[sagar]

How to get a 2D radiation pattern in XY or XZ direction. "Scat_ff" gives the radiation pattern only when there is no material interface or substrate. What to calculate the far field 2D radiation pattern with the substrate. 

In my case, the electric dipole is sitting inside a pillar of material 1 and the x direction. The pillar is in a material 2/substrate. The pillar axis is along z. I want to see the radiation profile along xz and yz. 

[Amrita Pati]

Hi Sagar,

I see that you have another post on this a while back that no one else has replied yet. Sorry about that.

I haven't used "scat_ff" a lot myself. But the page on Far-field projections from a box monitor mentions this:

Note: Particle scattering with a substrate

The 'box of monitor' far field projection is frequently used when studying particle scattering. This is fine, but it's important to remember the requirement that everything beyond the monitor box must be a single homogeneous material. When a substrate is present, this approach is not valid. Instead, the best way to calculate the far field scattering pattern is to use a single monitor, located above or below the particle (depending if you want scattering in the forward or backwards direction). You can then use the standard farfield3d function. When using a single monitor, it's important to make the simulation span large enough that most of the scattered light will pass through the monitor before hitting the PML absorbing boundary conditions.

Let me know if this doesn't help. I will get someone else to provide more insights.

Regards,
Amrita

 

[sagar]

Thank you Amrita for the reply. 

Placing the monitor at the top and bottom is fine, I have done that for comparing forward and backward emissions. But I want to see the the radiation profile of the dipole placed inside the metasurface, and how it couples to the outside and the substrate. Radiation along XZ and YZ will tell about how symmetric the radiations are, which is needed for my case. Please find something if it is possible to calculate.

Even if I use this "Scat_ff" object how much error will it introduce in the result? Will it be totally wrong?

 Even it has helped me to get some ideas for further analysis. So it would be great if I am able to show some radiation profiles in my article. 

 

Thanking you,

 SAGAR

 

 

[Amrita Pati]

Hi Sagar,

Thanks for sharing more information. I will discuss this with my colleague today and get back to you.

Regards,
Amrita

[Amrita Pati]

Hi Sagar,

I am sorry about the late reply. Unfortunately we don't recommend using the box monitor because it only works under the assumption that the region where the monitor is placed and beyond is homogenous. So, we can not guarantee how accurate the results will be. I understand that you want to look at the XZ and the YZ plane, but the best approach here is to make the simulation region extremely large and the add the 2D monitors at the top and the bottom so that most of the total radiation is captured by these monitors. This won't give you the XZ and YZ pattern but at least you can get some insights into the total radiation pattern without having to use the box monitors.

I was told that the "directivity" analysis group might be helpful but I haven't managed to make it work myself. 

Regards,
Amrita

[sagar]

Dear Amrita,

I think we can split the box monitor into two parts, the first part will cover the metasurface and will have five faces instead of six. The bottom monitor which is "z1" would not collect any field information and the field information recorded in the "five-faced box monitor" will be projected at 0 to 2pi angle and the same way we can place the second box monitor in the substrate to record the field contribution. Like before in this case the "z2" monitor will not be taken into account so whatever comes back to the substrate will get collected and a similar way will be projected in 2pi to 4pi angle. Both "five-faced box monitors" eventually cover all the 2D radiation patterns by passing through the dielectric interfaces. Please comment on it. If it is a valid idea can you please modify the codes? I am also trying from my side.