How are B1 Maps Calculated in OpenEMS?

How to use openEMS. Discussion on examples, tutorials etc

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How are B1 Maps Calculated in OpenEMS?

Post by Matty » Thu 16 Sep 2021, 23:04

Hello Thorsten & Forum,

To preface my question, I am a complete newbie when it comes to modelling and the FDTD method. I have been working through the tutorials over the last few days to get a grasp of the openEMS software. I have worked my way up to the MRI coil tutorials, as this is my use case for openEMS. However - I am slightly confused about the B1 +/- output that the software gives. Does openEMS compute the B +/- from the H-field at a given point in time? As an example, if I ran the simulation for 1e4 steps, would the output B1 field be from the final simulation time step? Or is the output more complex? I am not very familiar with HDF5 files so I am not sure what data is being pulled from them.

Thank you for your time,

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Re: How are B1 Maps Calculated in OpenEMS?

Post by thorsten » Thu 23 Sep 2021, 09:15


that were many questions at once? Usually the B1 is calculated in frequency domain as a complex value (using a DFT of the time-domain values during simulation or in post-processing). And for MRI you are usually only interested in a single frequency.
Somthing like B1^+ = u0 * (Hx + j * Hy)
But I would have to check to be sure.

There are tools like hdfview to inspect hdf5 files. Otherwise just read about the hdf5 format.


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