Dear Sir,
We are using HFSS Simulator and trying to plot radiation pattern for two case, of a slot cut on waveguide wall as fallowed
Case one:
A slot cut on broad wall of waveguide located quarter wave away from shorting placed at one end of waveguide.
Case two:
A slot cut on narrow wall of waveguide located quarter wave away from shorting placed at one end of waveguide.
The waveguide length is taken typically 200mm.
Global coordinate is laying at the center of the waveguide.
After executing the model and displaying the 3D radiation pattern, displayed pattern is centered at the present coordinate system ie at the center of the waveguide. But we want it should be at center of the slot which is cut on the broader wall of the waveguide and located at around 12 mm away from the shorted port of the wave guide. Can you please tell us how to relocate or plot the radiation pattern cantered at the slot of given waveguide structure.
One way to do this is to rebuild the entire model with respect to coordinate centered at the slot of the waveguide structure. But this will be a very Involved and time taking work, to model and always may not be possible. Thus we are looking some other approach. Please tell us how to proceed.
any ones early reply/suggestion in this regard will be highly appreciated.
Thank you
It makes no difference to the radiation pattern where the centre is. The pattern will not change. It is a far-field pattern and only depends on angle, not distance.
The only thing that changes is the phase. You can add the phase in by adding r.v 2 pi/wavelength to the phase at every direction, where r.v is the scalar vector product between "r" the far-field direction unit vector, and "v" the vector describing the movement of the antenna from where it was when you calculated the pattern.
This phase mostly only matters if
1. You want to know the absolute phase between two antennas
2. You want to combine a number of slots as an array, and you want to add their patterns together.
3. The antenna is rotating, and you don't want the phase to vary as it rotates (so you try to make the rotation centre the same as the "phase" centre).
Dear Shrivastav a.k. Sir,
Please use the following steps:
1. Create an offset coordinate system with origin as your slot center
2. now create a infinite sphere with required theta/phi range and use this coordinates system in setup.
3. Plot radiation pattern by using this infinite sphere..
Pics are attached for your ref.
Regards
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