update example: Rect_Waveguide

matlab/examples/waveguide/Rect_Waveguide.m

@@ -1,36 +1,65 @@
+%
+% EXAMPLE / waveguide / Rect_Waveguide
+%
+% This example demonstrates:
+%  - waveguide mode excitation
+%  - waveguide mode matching
+%  - pml absorbing boundaries
+% 
+%
+% Tested with
+%  - Matlab 2009b
+%  - openEMS v0.0.17
+%
+% (C) 2010 Thorsten Liebig <thorsten.liebig@gmx.de>
+
 close all
 clear
 clc
 
-%% setup the simulation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% switches
-length = 2000;
+postproc_only = 1;
-unit = 1e-3;
-a = 1000;
-width = a;
-b = 500;
-height = b;
-mesh_res = [10 10 10];
 
-%define mode
+%% setup the simulation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+physical_constants;
+unit = 1e-3; %drawing unit in mm
+numTS = 50000; %max. number of timesteps
+
+% waveguide dimensions
+length = 2000;
+a = 1000;   %waveguide width
+b = 600;    %waveguide heigth
+
+%waveguide TE-mode definition
 m = 1;
 n = 0;
 
-EPS0 = 8.85418781762e-12;
+mesh_res = [10 10 10];
-MUE0 = 1.256637062e-6;
-C0 = 1/sqrt(EPS0*MUE0);
-Z0 = sqrt(MUE0/EPS0);
 
-f0 = 1e9;
+%% setup FDTD parameters & excitation function %%%%%%%%%%%%%%%%%%%%%%%%%%%%
-freq = linspace(f0-f0/3,f0+f0/3,201);
+f_start =  175e6;
+f_stop  =  500e6;
 
-k = 2*pi*freq/C0;
+% dump special frequencies to vtk, use paraview (www.paraview.org) to
+% animate this dumps over phase
+vtk_dump_freq = [200e6 300e6 500e6];
+
+freq = linspace(f_start,f_stop,201);
+
+k = 2*pi*freq/c0;
 kc = sqrt((m*pi/a/unit)^2 + (n*pi/b/unit)^2);
-fc = C0*kc/2/pi;
+fc = c0*kc/2/pi;          %cut-off frequency
-beta = sqrt(k.^2 - kc^2);
+beta = sqrt(k.^2 - kc^2); %waveguide phase-constant
+ZL_a = k * Z0 ./ beta;    %analytic waveguide impedance
 
-ZL_a = k * Z0 ./ beta; 
+disp([' Cutoff frequencies for this mode and wavguide is: ' num2str(fc/1e6) ' MHz']);
+
+if (f_start<fc)
+    warning('openEMS:example','f_start is smaller than the cutoff-frequency, this may result in a long simulation... ');
+end
 
 %% mode functions %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% by David M. Pozar, Microwave Engineering, third edition, page 113
 func_Ex = [num2str( n/b/unit) '*cos(' num2str(m*pi/a) '*x)*sin('  num2str(n*pi/b) '*y)'];
 func_Ey = [num2str(-m/a/unit) '*sin(' num2str(m*pi/a) '*x)*cos('  num2str(n*pi/b) '*y)'];
 
@@ -41,7 +70,7 @@ func_Hy = [num2str(n/b/unit) '*cos(' num2str(m*pi/a) '*x)*sin('  num2str(n*pi/b)
 openEMS_opts = '';
 % openEMS_opts = [openEMS_opts ' --disable-dumps'];
 % openEMS_opts = [openEMS_opts ' --debug-material'];
-openEMS_opts = [openEMS_opts ' --engine=fastest'];
+% openEMS_opts = [openEMS_opts ' --engine=basic'];
 
 Settings = [];
 Settings.LogFile = 'openEMS.log';
@@ -49,27 +78,29 @@ Settings.LogFile = 'openEMS.log';
 Sim_Path = 'tmp';
 Sim_CSX = 'rect_wg.xml';
 
-if (exist(Sim_Path,'dir'))
+if (postproc_only==0)
-    rmdir(Sim_Path,'s');
+    if (exist(Sim_Path,'dir'))
+        rmdir(Sim_Path,'s');
+    end
+    mkdir(Sim_Path);
 end
-mkdir(Sim_Path);
 
 %% setup FDTD parameter & excitation function %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-FDTD = InitFDTD(50000,1e-5,'OverSampling',6);
+FDTD = InitFDTD(numTS,1e-5,'OverSampling',6);
-FDTD = SetGaussExcite(FDTD,f0,f0/3);
+FDTD = SetGaussExcite(FDTD,0.5*(f_start+f_stop),0.5*(f_stop-f_start));
 BC = [0 0 0 0 0 3];
 FDTD = SetBoundaryCond(FDTD,BC);
 
 %% setup CSXCAD geometry & mesh %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 CSX = InitCSX();
-mesh.x = 0 : mesh_res(1) : width;
+mesh.x = SmoothMeshLines([0 a], mesh_res(1));
-mesh.y = 0 : mesh_res(2) : height;
+mesh.y = SmoothMeshLines([0 b], mesh_res(2));
-mesh.z = 0 : mesh_res(3) : length;
+mesh.z = SmoothMeshLines([0 length], mesh_res(3));
 CSX = DefineRectGrid(CSX, unit,mesh);
 
 %% apply the excitation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-start=[0     0      mesh.z(1) ];
+start=[mesh.x(1)   mesh.y(1)   mesh.z(1) ];
-stop =[width height mesh.z(1) ];
+stop =[mesh.x(end) mesh.y(end) mesh.z(1) ];
 CSX = AddExcitation(CSX,'excite',0,[1 1 0]);
 weight{1} = func_Ex;
 weight{2} = func_Ey;
@@ -78,6 +109,7 @@ CSX = SetExcitationWeight(CSX,'excite',weight);
 CSX = AddBox(CSX,'excite',0 ,start,stop);
 
 %% voltage and current definitions using the mode matching probes %%%%%%%%%
+%port 1
 start = [mesh.x(1)   mesh.y(1)   mesh.z(15)];
 stop  = [mesh.x(end) mesh.y(end) mesh.z(15)];
 CSX = AddProbe(CSX, 'ut1', 10, 1, [], 'ModeFunction',{func_Ex,func_Ey,0});
@@ -85,6 +117,7 @@ CSX = AddBox(CSX,  'ut1',  0 ,start,stop);
 CSX = AddProbe(CSX,'it1', 11, 1, [], 'ModeFunction',{func_Hx,func_Hy,0});
 CSX = AddBox(CSX,'it1', 0 ,start,stop);
 
+%port 2
 start = [mesh.x(1)   mesh.y(1)   mesh.z(end-15)];
 stop  = [mesh.x(end) mesh.y(end) mesh.z(end-15)];
 CSX = AddProbe(CSX, 'ut2', 10, 1, [], 'ModeFunction',{func_Ex,func_Ey,0});
@@ -94,18 +127,19 @@ CSX = AddBox(CSX,'it2', 0 ,start,stop);
  
 %% define dump boxes... %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 CSX = AddDump(CSX,'Et','FileType',1,'SubSampling','4,4,2');
-start = [mesh.x(1) , height/2 , mesh.z(1)];
+start = [mesh.x(1)   mesh.y(1)   mesh.z(1)];
-stop = [mesh.x(end) ,  height/2 , mesh.z(end)];
+stop  = [mesh.x(end) mesh.y(end) mesh.z(end)];
 CSX = AddBox(CSX,'Et',0 , start,stop);
 
 CSX = AddDump(CSX,'Ht','DumpType',1,'FileType',1,'SubSampling','4,4,2');
 CSX = AddBox(CSX,'Ht',0,start,stop);
 
 %% Write openEMS compatoble xml-file %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-WriteOpenEMS([Sim_Path '/' Sim_CSX],FDTD,CSX);
+if (postproc_only==0)
-
+    WriteOpenEMS([Sim_Path '/' Sim_CSX],FDTD,CSX);
-RunOpenEMS(Sim_Path, Sim_CSX, openEMS_opts, Settings)
 
+    RunOpenEMS(Sim_Path, Sim_CSX, openEMS_opts, Settings)
+end
 
 %% postproc %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 U = ReadUI({'ut1','ut2'},[Sim_Path '/'],freq);
@@ -127,7 +161,7 @@ if1_ref = if1 - if1_inc;
 uf2_ref = uf2 - uf2_inc;
 if2_ref = if2 - if2_inc;
 
-%% plot s-parameter
+%% plot s-parameter %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 figure
 s11 = uf1_ref./uf1_inc;
 s21 = uf2_inc./uf1_inc;
@@ -141,7 +175,7 @@ legend('s11','s21','Location','SouthEast');
 ylabel('s-para (dB)');
 xlabel('freq (Hz)');
 
-%% compare analytic and numerical wave-impedance
+%% compare analytic and numerical wave-impedance %%%%%%%%%%%%%%%%%%%%%%%%%%
 ZL = uf1./if1;
 figure()
 plot(freq,real(ZL),'Linewidth',2);
@@ -154,3 +188,41 @@ xlabel('freq (Hz)');
 xlim([freq(1) freq(end)]);
 legend('\Re(Z_L)','\Im(Z_L)','Z_L analytic','Location','Best');
 
+%% Plot the field dumps %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+dump_file = [Sim_Path '/Et.h5'];
+figure()
+PlotArgs.slice = {a/2*unit b/2*unit 0};
+PlotArgs.pauseTime=0.01;
+PlotArgs.component=0;
+PlotArgs.Limit = 'auto';
+PlotHDF5FieldData(dump_file, PlotArgs)
+
+%% dump frequency to vtk %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% cleanup and create dump folder
+vtk_path = [Sim_Path '/vtk'];
+if exist(vtk_path,'dir')
+    rmdir(vtk_path,'s');
+end
+mkdir(vtk_path);
+
+disp('Dumping to vtk files... this may take a minute...')
+% define interpolation mesh
+mesh_interp{1}=mesh.x * unit;
+mesh_interp{2}=b/2 * unit;
+mesh_interp{3}=mesh.z * unit;
+[field_FD mesh_FD] = ReadHDF5Dump(dump_file,'Interpolation',mesh_interp,'Frequency',vtk_dump_freq);
+
+% dump animated phase to vtk
+for n=1:numel(vtk_dump_freq)   
+    phase = linspace(0,360,21);
+    phase = phase(1:end-1);
+    for ph = phase
+        filename = [vtk_path '/E_xz_f=' num2str(vtk_dump_freq(n)) '_p' num2str(ph) '.vtk'];
+        Dump2VTK(filename,real(field_FD.values{n}.*exp(1j*ph/180*pi)),mesh_FD,'E-Field');
+    end
+    
+    filename = [vtk_path '/E_xz_f=' num2str(vtk_dump_freq(n)) '_mag.vtk'];
+    Dump2VTK(filename,abs(field_FD.values{n}),mesh_FD,'E-Field');
+end
+
+disp('done... you can open and visualize the vtk-files using Paraview (www.paraview.org)!')