Can I do such a simulation?

How to use openEMS. Discussion on examples, tutorials etc

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Katrina
Posts: 12
Joined: Tue 25 May 2021, 03:38

Can I do such a simulation?

Post by Katrina » Mon 08 Nov 2021, 06:10

Hi guys:


Can I do such a simulation: radiate a model with a plane wave, then set a probe on the model to detect the electric field and magnetic field radiated to the model, and finally draw a two-dimensional broken line diagram of the electric field or magnetic field at a certain point on the model with drawing software? What I want to know is, can this software be used to calculate the electromagnetic field of the model? If anyone knows, I would appreciate it if you could give me some suggestions.

thorsten
Posts: 1477
Joined: Mon 27 Jun 2011, 12:26

Re: Can I do such a simulation?

Post by thorsten » Tue 09 Nov 2021, 18:49

You can dump (that means store) any E- or H-field anywhere and in time- or frequency domain e.g. to an hdf5 file.
What you later on do with this data and how you visualize it, is completely up to you and your imagination...

regards,
Thorsten

Katrina
Posts: 12
Joined: Tue 25 May 2021, 03:38

Re: Can I do such a simulation?

Post by Katrina » Wed 10 Nov 2021, 11:41

hi Thorsten:
Thanks for your reply,First of all, I don't think there is a problem with your program. I just don't know what the 'et' in adddump (CSX, 'et') means, does it mean the electric field distribution on the whole surface or what. I draw the data in the result with the drawing software. The waveform seems to be close to the waveform of the excitation source, so I'm not sure where the data in this file is the electric field or whether it is the result I want.
Besides, I have another question. If I want to know the electric field value at a certain point in the model, what should I do?
best,
Kartrina

Muhamed96
Posts: 3
Joined: Wed 22 Dec 2021, 07:58

Re: Can I do such a simulation?

Post by Muhamed96 » Wed 22 Dec 2021, 08:16

Hello,

since this is my first reply on this forum, I want to apologize in andvance, if my answer is not completely correct. While I have a couple of years experience using EM Simulation tools, I'm just about 6 months into using openEMS :D .

As fas as I understand, the 'et' is the electric field distribution in time domain. So when you visualise the data, you basically see the Gaussian excitation (assuming you used the SetGaussExcite command) pulse over time. If you however want to look at the electric field at a given frequency, you would probably have to do a fft from the time domain data, but I haven't tried that yet, so I cant report about that.

For field visualisation I have been using the AddBox() command to define the region in which I want to see the fields. From the dumped/exported field data, you can probaly determine the x,y and z coordinates as well as the amplitude. So basically, you would import the exported simulation data in Matlab/Octave, find the desired coordinate (and conversely the amplitude and time) and plot it over time (or do a fft and plot it over frequency).

Another possibility might be to define the field recording box at only the desired point, so you wouldn't have to search for it in the postprocessing step. However, I haven't yet tried, to record only one point of my field, so maybe someone more experienced can report about it.

Regards,
Muhamed

thorsten
Posts: 1477
Joined: Mon 27 Jun 2011, 12:26

Re: Can I do such a simulation?

Post by thorsten » Sun 26 Dec 2021, 21:06

Thanks Muhamed for your answer,

On note from my side, the "et" name in the context of AddDump really is just a name for the file and nothing more. You can name it whatever you want...
If you look into "help AddDump" you get all the additional options and will notice that the electric field in time-domain is just the default setting.
If you want a dump in frequency domain you have to specify DumpType 10 and give a list of frequencies to be used. But if you need many it may be better/faster to dump in time-domain and apply a dft/fft later yourself.

Please note that there is always a file called "et" only and it contains the excitation (time) signal only and should not be confused with a dump box given the same name.

regards
Thorsten

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