Search found 1468 matches

by thorsten
Mon 11 Oct 2021, 22:30
Forum: Usage
Topic: Cylindrical coordinates Boundary and embedded mesh
Replies: 2
Views: 385

Re: Cylindrical coordinates Boundary and embedded mesh

Hi, for r_0 and a_0 and a_max you should just define PEC (kind of the default as it is always there in any case)... e.g. BC = [0, 3, 0, 0, 3, 3] The engine should detect the grid type and implement the special boundary conditions as needed anyways. It is very important that the mesh in alpha directi...
by thorsten
Sun 03 Oct 2021, 19:05
Forum: Usage
Topic: CalcNF2FF no vtk file when using circular coordinates
Replies: 2
Views: 333

Re: CalcNF2FF no vtk file when using circular coordinates

This function never creates a vtk file.
Maybe in your other script you use "DumpFF2VTK" as well?
As far as I see it, the ff-pattern should not care anymore what the FDTD mesh looked like...

regards
Thorsten
by thorsten
Sun 03 Oct 2021, 19:01
Forum: Usage
Topic: Understanding Antenna efficiency
Replies: 1
Views: 294

Re: Understanding Antenna efficiency

1) yes this levels are (most likely) correct. Use the file "et" and converted to ef (frequency domain) no normalize out the effect of the excitation pulse amplitude. 2) That depends on what the script actually calculates. I'm usually only interested in the antenna efficiency only as fixing a mismatc...
by thorsten
Sun 03 Oct 2021, 18:56
Forum: Usage
Topic: How to simulate material with magnetic loss using openEMS?
Replies: 1
Views: 311

Re: How to simulate material with magnetic loss using openEMS?

Yes magnetic losses can be used. See "help AddMaterial"

br
Thorsten
by thorsten
Fri 24 Sep 2021, 07:34
Forum: Usage
Topic: Simple skin effect compensation works but is it valid???
Replies: 3
Views: 429

Re: Simple skin effect compensation works but is it valid???

Hi again, okay then I misunderstood or misread ;) I though you were expecting 36Ohms and got only 2... To be honest, for such low frequencies I would not even bother with ohmic losses, they are usually negligible at least for antennas like this. I would expect a measured efficiency of >90%. And no m...
by thorsten
Thu 23 Sep 2021, 09:15
Forum: Usage
Topic: How are B1 Maps Calculated in OpenEMS?
Replies: 1
Views: 338

Re: How are B1 Maps Calculated in OpenEMS?

Hi, 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 ...
by thorsten
Thu 23 Sep 2021, 09:10
Forum: Usage
Topic: Simple skin effect compensation works but is it valid???
Replies: 3
Views: 429

Re: Simple skin effect compensation works but is it valid???

Hi, well this does not really sound to good. If your antenna would be working properly you should get much higher R indeed, but not because of (heating) losses, but because of radiation (kind of matching to the 377Ohms of free space). I have the feeling you just replaced the (missing?) radiation wit...
by thorsten
Thu 23 Sep 2021, 09:04
Forum: Usage
Topic: EC FDTD algorithm adopted by openEMS
Replies: 1
Views: 252

Re: EC FDTD algorithm adopted by openEMS

Hi, from a user perspective you should not care about the EC (equivalent circuit) part. It's just a different way of calculating the (same) FDTD coefficients. At the end the engine behaves 100% identical to a plain and simple FDTD method. Only if you want to extent and develop on openEMS it would he...
by thorsten
Tue 14 Sep 2021, 20:58
Forum: Usage
Topic: Reason for nan energy levels?
Replies: 6
Views: 847

Re: Reason for nan energy levels?

Okay openEMS is not directly responsible, your mesh is broken: >> min(diff(mesh.x)) ans = 0.050000 >> min(diff(mesh.y)) ans = 6.8580e-16 >> min(diff(mesh.z)) ans = 0.094186 That is a bad mesh in y-direction that the simple float accuracy could not handle... I'm a bit angry at myself that this was no...
by thorsten
Tue 14 Sep 2021, 19:53
Forum: Usage
Topic: Reason for nan energy levels?
Replies: 6
Views: 847

Re: Reason for nan energy levels?

First finding, the cylinder number 50 (and maybe every 50th) is flat like a circle and somehow openEMS does not like this... So you should make sure to avoid this at the moment, but I have to find out why, because a circle like this should not do anything! Edit: Doing this makes it run as expected: ...