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diff --git a/openEMS/matlab/Tutorials/Circ_Waveguide.m b/openEMS/matlab/Tutorials/Circ_Waveguide.m
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+%
+% Tutorials / Circ_Waveguide
+%
+% Describtion at:
+% http://openems.de/index.php/Tutorial:_Circular_Waveguide
+%
+% Tested with
+%  - Matlab 2011a / Octave 3.4.3
+%  - openEMS v0.0.31
+%
+% (C) 2010-2013 Thorsten Liebig <thorsten.liebig@gmx.de>
+
+close all
+clear
+clc
+
+%% setup the simulation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+physical_constants;
+unit = 1e-3; %drawing unit in mm
+
+% waveguide dimensions
+length = 2000;
+rad = 350;     %waveguide radius in mm
+
+% frequency range of interest
+f_start =  300e6;
+f_stop  =  500e6;
+
+mesh_res = [10 2*pi/49.999 10]; %targeted mesh resolution
+
+%% setup FDTD parameter & excitation function %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+FDTD = InitFDTD('EndCriteria',1e-4,'CoordSystem',1);
+FDTD = SetGaussExcite(FDTD,0.5*(f_start+f_stop),0.5*(f_stop-f_start));
+
+% boundary conditions
+BC = [0 0 0 0 3 3]; %pml in pos. and neg. z-direction
+FDTD = SetBoundaryCond(FDTD,BC);
+
+%% setup CSXCAD mesh %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+CSX = InitCSX('CoordSystem',1); % init a cylindrical mesh
+mesh.r = SmoothMeshLines([0 rad], mesh_res(1)); %mesh in radial direction
+mesh.a = SmoothMeshLines([0 2*pi], mesh_res(2)); % mesh in aziumthal dir.
+mesh.z = SmoothMeshLines([0 length], mesh_res(3));
+CSX = DefineRectGrid(CSX, unit,mesh);
+
+%% apply the waveguide port %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+start=[mesh.r(1)   mesh.a(1)   mesh.z(8)];
+stop =[mesh.r(end) mesh.a(end) mesh.z(15)];
+[CSX, port{1}] = AddCircWaveGuidePort( CSX, 0, 1, start, stop, rad*unit, 'TE11', 0, 1);
+
+start=[mesh.r(1)   mesh.a(1)   mesh.z(end-13)];
+stop =[mesh.r(end) mesh.a(end) mesh.z(end-14)];
+[CSX, port{2}] = AddCircWaveGuidePort( CSX, 0, 2, start, stop, rad*unit, 'TE11');
+
+%% define dump box... %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+CSX = AddDump(CSX,'Et','FileType',1,'SubSampling','4,4,4');
+start = [mesh.r(1)   mesh.a(1)   mesh.z(1)];
+stop  = [mesh.r(end) mesh.a(end) mesh.z(end)];
+CSX = AddBox(CSX,'Et',0 , start,stop);
+
+%% Write openEMS compatoble xml-file %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+Sim_Path = 'tmp';
+Sim_CSX = 'circ_wg.xml';
+
+[status, message, messageid] = rmdir(Sim_Path,'s');
+[status, message, messageid] = mkdir(Sim_Path);
+
+WriteOpenEMS([Sim_Path '/' Sim_CSX],FDTD,CSX);
+
+RunOpenEMS(Sim_Path, Sim_CSX)
+
+%% postproc %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+freq = linspace(f_start,f_stop,201);
+port = calcPort( port, Sim_Path, freq);
+
+s11 = port{1}.uf.ref./ port{1}.uf.inc;
+s21 = port{2}.uf.ref./ port{1}.uf.inc;
+ZL = port{1}.uf.tot./port{1}.if.tot;
+
+
+%% plot s-parameter %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+figure
+plot(freq*1e-6,20*log10(abs(s11)),'k-','Linewidth',2);
+xlim([freq(1) freq(end)]*1e-6);
+grid on;
+hold on;
+plot(freq*1e-6,20*log10(abs(s21)),'r--','Linewidth',2);
+l = legend('S_{11}','S_{21}','Location','Best');
+set(l,'FontSize',12);
+ylabel('S-Parameter (dB)','FontSize',12);
+xlabel('frequency (MHz) \rightarrow','FontSize',12);
+
+%% compare analytic and numerical wave-impedance %%%%%%%%%%%%%%%%%%%%%%%%%%
+figure
+plot(freq*1e-6,real(ZL),'Linewidth',2);
+hold on;
+grid on;
+plot(freq*1e-6,imag(ZL),'r--','Linewidth',2);
+plot(freq*1e-6,port{1}.ZL,'g-.','Linewidth',2);
+ylabel('ZL (\Omega)','FontSize',12);
+xlabel('frequency (MHz) \rightarrow','FontSize',12);
+xlim([freq(1) freq(end)]*1e-6);
+l = legend('\Re(Z_L)','\Im(Z_L)','Z_L analytic','Location','Best');
+set(l,'FontSize',12);
+