118 lines
3.6 KiB
Matlab
118 lines
3.6 KiB
Matlab
%
|
|
% Tutorials / Rect_Waveguide
|
|
%
|
|
% Describtion at:
|
|
% http://openems.de/index.php/Tutorial:_Rectangular_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 = 5000;
|
|
a = 1000; %waveguide width
|
|
b = 1000; %waveguide heigth
|
|
|
|
% frequency range of interest
|
|
f_start = 300e6;
|
|
f_stop = 500e6;
|
|
|
|
%waveguide TE-mode definition
|
|
TE_mode = 'TE11';
|
|
|
|
mesh_res = [10 10 10]; %targeted mesh resolution
|
|
|
|
%% setup FDTD parameter & excitation function %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
FDTD = InitFDTD();
|
|
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();
|
|
mesh.x = SmoothMeshLines([0 a], mesh_res(1));
|
|
mesh.y = SmoothMeshLines([0 b], mesh_res(2));
|
|
mesh.z = SmoothMeshLines([0 length], mesh_res(3));
|
|
CSX = DefineRectGrid(CSX, unit,mesh);
|
|
|
|
%% apply the waveguide port %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
start=[mesh.x(1) mesh.y(1) mesh.z(8)];
|
|
stop =[mesh.x(end) mesh.y(end) mesh.z(15)];
|
|
[CSX, port{1}] = AddRectWaveGuidePort( CSX, 0, 1, start, stop, 2, a*unit, b*unit, TE_mode, 1);
|
|
|
|
start=[mesh.x(1) mesh.y(1) mesh.z(end-13)];
|
|
stop =[mesh.x(end) mesh.y(end) mesh.z(end-14)];
|
|
[CSX, port{2}] = AddRectWaveGuidePort( CSX, 0, 2, start, stop, 2, a*unit, b*unit, TE_mode);
|
|
|
|
%% define dump box... %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
CSX = AddDump(CSX,'Et','FileType',1,'SubSampling','4,4,4');
|
|
start = [mesh.x(1) mesh.y(1) mesh.z(1)];
|
|
stop = [mesh.x(end) mesh.y(end) mesh.z(end)];
|
|
CSX = AddBox(CSX,'Et',0 , start,stop);
|
|
|
|
%% Write openEMS compatoble xml-file %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
Sim_Path = 'tmp_mod';
|
|
Sim_CSX = 'rect_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;
|
|
ZL_a = port{1}.ZL; % analytic waveguide impedance
|
|
|
|
%% 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,ZL_a,'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);
|
|
|
|
%% Plot the field dumps %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
|
figure
|
|
dump_file = [Sim_Path '/Et.h5'];
|
|
PlotArgs.slice = {a/2*unit b/2*unit 0};
|
|
PlotArgs.pauseTime=0.01;
|
|
PlotArgs.component=0;
|
|
PlotArgs.Limit = 'auto';
|
|
PlotHDF5FieldData(dump_file, PlotArgs)
|