Search found 31 matches

by MPCEngineer
Wed 06 Oct 2021, 12:12
Forum: Usage
Topic: Cylindrical coordinates Boundary and embedded mesh
Replies: 2
Views: 1494

Re: Cylindrical coordinates Boundary and embedded mesh

I have also noticed for cylindrical coordinates that using 'MUR' boundary conditions the energy does not always tend to zero. I assume this is because a 'MUR' boundary only absorbs energy that is orthogonal. If I use: BC = {'PML_8' 'PML_8' 'PML_8' 'PML_8' 'PML_8' 'PML_8'}; % boundary conditions FDTD...
by MPCEngineer
Mon 04 Oct 2021, 18:06
Forum: Usage
Topic: Cylindrical coordinates Boundary and embedded mesh
Replies: 2
Views: 1494

Cylindrical coordinates Boundary and embedded mesh

Hi Thorsten, I have read your paper, a free and open source equivalent-circuit (EC) FDTD simulation platform supporting cylindrical coordinates suitable for the analysis of traveling wave MRI applications. On the Openems wiki page https://openems.de/index.php/FDTD_Mesh.html there is an example of a ...
by MPCEngineer
Mon 04 Oct 2021, 09:24
Forum: Usage
Topic: CalcNF2FF no vtk file when using circular coordinates
Replies: 3
Views: 1571

Re: CalcNF2FF no vtk file when using circular coordinates

Hi Thorsten,

Thank you, yes you are correct. I am very grateful to you for pointing that out.

MPC.
by MPCEngineer
Fri 01 Oct 2021, 17:57
Forum: Usage
Topic: CalcNF2FF no vtk file when using circular coordinates
Replies: 3
Views: 1571

CalcNF2FF no vtk file when using circular coordinates

Hi, I am using circular coordinates and the CalcNF2FF does not produce a .vtk file I use the following to define circular coordinates: FDTD = InitFDTD('CoordSystem', 1); % init a cylindrical FDTD The following is the CalcNF2FF call: disp( 'calculating 3D far field pattern and dumping to vtk (use Par...
by MPCEngineer
Wed 29 Sep 2021, 11:51
Forum: Usage
Topic: Understanding Antenna efficiency
Replies: 1
Views: 1074

Understanding Antenna efficiency

Hi All, On many example scripts the antenna efficiency is given as disp( ['efficiency: nu_rad = ' num2str(100*nf2ff.Prad./P_in_0) ' %']); where P_in_0 is the power in at the frequency of interest and calculated from port.P_acc accepted power. nf2ff.Prad is the total radiated power from the antenna. ...
by MPCEngineer
Thu 23 Sep 2021, 14:19
Forum: Usage
Topic: Simple skin effect compensation works but is it valid???
Replies: 3
Views: 1517

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

Hi Thorsten, The antenna is a normal mode helix. From the research I have done a normal mode helix antenna (NMHA) should have a very low impedance (less than two ohms). If I use a perfect conductor for the Helix openEMS does suggest a very low impedance at normal mode resonance which agrees with the...
by MPCEngineer
Wed 22 Sep 2021, 13:12
Forum: Usage
Topic: Another question on Tutorial: Parallel Plate Waveguide
Replies: 4
Views: 1586

Re: Another question on Tutorial: Parallel Plate Waveguide

Did you click on SOLID COLOR and then choose E-Field?
by MPCEngineer
Wed 22 Sep 2021, 12:13
Forum: Usage
Topic: Simple skin effect compensation works but is it valid???
Replies: 3
Views: 1517

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

Hi All, I have been experimenting and simulating a normal mode helix antenna using OpenEMS and after a lot of work on the mesh and help from the forum I have been able to achieve a really good resonance match with physical results. The problem has been the antenna impedance at resonance. I was simul...
by MPCEngineer
Wed 22 Sep 2021, 11:38
Forum: Usage
Topic: Another question on Tutorial: Parallel Plate Waveguide
Replies: 4
Views: 1586

Re: Another question on Tutorial: Parallel Plate Waveguide

Hi, At the start I struggled with paraview but I found after lots of experimentation it is a very powerful visual aid. I have not used the parallel waveguide example but my experience as a newbie, you need to ensure you click on the group vtr. You need look in the colouring section and click on soli...
by MPCEngineer
Wed 22 Sep 2021, 11:20
Forum: Usage
Topic: Question regarding getting started tutorial
Replies: 4
Views: 1541

Re: Question regarding getting started tutorial

Hi,

I am also new to OpenEMS but from my experience you must create the mesh lines manually and they are critical. You need to spend time ensuring you have the mesh setup correctly.

Its a good idea to include the script file you are using so it can be scrutinised.

MPC.