CreateNF2FFBox - box size

How to use openEMS. Discussion on examples, tutorials etc

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davidsmith52
Posts: 1
Joined: Tue 25 Jun 2019, 17:46

CreateNF2FFBox - box size

Post by davidsmith52 » Thu 25 Jul 2019, 01:46

Hi.

I've been learning to use the excellent openEMS with a view toward testing some antenna array ideas. So of course I'm interested in CalcNF2FF.

I can easily simulate a single patch antenna, like the Patch_Antenna example. However, when I increase the dimensions of the nf2ff dump box (except the normal dimension), the far-field pattern becomes distorted. Also, if I use the Patch_Antenna_Array example (which uses a larger box) but only excite the first patch, I see the same pattern distortion, not the pattern expected for a single patch.

The distortion gets worse as the dimensions of the box (except the normal) increase. The normal dimension has little effect.

I have tried increasing the mesh resolution and the number of timesteps, but there is very little effect. I have increased the far field radius to 2, 4, and 8 meters, also with no real effect.

So wonder if this is expected behavior, or if what seems like a distorted pattern is actually correct, or if there is something I should do to correct it. Any help is appreciated!

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