# Near field - far field transformation

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Estelle Wuilliez on 28 Apr 2015
Commented: fathema farjana on 21 Apr 2022
Hello,
I would like to do a near field - far field transformation with MATLAB.
I have near-field datas which look like : (sorry for all the dots)
x(mm)... y(mm)... z(mm)... Re(Ex)... Im(Ex)... Re(Ey)... Im(Ey)... Re(Ez)... Im(Ez)
46,8...... 33,2.......... 5......... -1,11...... 0,116..... 1,99........ 2,38...... -4,44...... -6,57
40,6...... 28,7.......... 5......... -1,46...... 0,123..... 1,35....... 3,7......... -3,49...... -9,88
There is 256 lines.
With these datas, I can display a plane that shows the near E-field of my microstrip antenna (at z = 5mm here).
For the moment, I just put Re(Ex)+i.Im(Ex), Re(Ey)+i.Im(Ey) and Re(Ez)+i.Im(Ez) in a same matrix.
I know I should use fft or something like "plane wave spectrum" but I don't know how.
In the end, I would like to display a plane that shows the far E-field (z = 500mm for example).
Any idea to help me would be welcome !
Thank you

Shashank Kulkarni on 28 Apr 2015
Hello Estelle,
Are you using Antenna Toolbox? Antenna Toolbox has built-in functionality to calculate the near and the far-fields for a given antenna structure. pattern function lets you calculate and plot the far fields. The function EHFields can calculate the E and H fields at any point in space (near or far).
The capability to do near to far field transformation does not currently exist in Antenna Toolbox.
I hope this helps.
Estelle Wuilliez on 29 Apr 2015
No, I am using the software tool Feko for the model and the simulation. But I'll have a look at Antenna Toolbox.
Thank you!
fathema farjana on 21 Apr 2022
@Estelle Wuilliez have you done this? i am facing the similar problem. Can you help me with that?

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