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Diffstat (limited to 'openEMS/matlab/examples/transmission_lines/CPW_Line.m')
| -rw-r--r-- | openEMS/matlab/examples/transmission_lines/CPW_Line.m | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/openEMS/matlab/examples/transmission_lines/CPW_Line.m b/openEMS/matlab/examples/transmission_lines/CPW_Line.m new file mode 100644 index 0000000..6dac636 --- /dev/null +++ b/openEMS/matlab/examples/transmission_lines/CPW_Line.m @@ -0,0 +1,125 @@ +% +% Tutorials / CPW_Line +% +% Describtion at: +% +% Tested with +% - Octave 3.8.1 +% - openEMS v0.0.32 +% +% (C) 2014 Thorsten Liebig <thorsten.liebig@gmx.de> + +close all +clear +clc + +%% setup the simulation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +physical_constants; +unit = 1e-6; % specify everything in um +CPW_length = 40000; +CPW_port_length = 10000; +CPW_width = 1000; +CPW_gap = 140; +substrate_thickness = 512; +substrate_width = 5000 +substrate_epr = 3.66; +f_max = 10e9; +air_spacing = 7000 + +% use a finite line CPW waveguide +if 1 + feed_R = 50; + pml_add_cells = [8 8 8 8 8 8]; + feed_shift_cells = 0; + x_spacing = air_spacing; +else % or use a waveguide with start/end in a pml + feed_R = inf; % CPW ends in a pml --> disable termination resitance + feed_shift_cells = 10; % CPW ends in an 8 cells thick pml --> shift feed 10 cells + pml_add_cells = [0 0 8 8 8 8]; % do not add air-space in x-direction + x_spacing = 0; % do not add air-space in x-direction +end + +%% setup FDTD parameters & excitation function %%%%%%%%%%%%%%%%%%%%%%%%%%%% +FDTD = InitFDTD('EndCriteria', 1e-4); +FDTD = SetGaussExcite( FDTD, f_max/2, f_max/2 ); +BC = [2 2 2 2 2 2]; +FDTD = SetBoundaryCond( FDTD, BC ); + +%% setup CSXCAD geometry & mesh %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +CSX = InitCSX(); +resolution = c0/(f_max*sqrt(substrate_epr))/unit /30; % resolution of lambda/50 +edge_res = 40; +mesh.x = SmoothMeshLines( [0 CPW_length/2 CPW_length/2+x_spacing], resolution, 1.5 ,0 ); +mesh.x = unique(sort([-mesh.x mesh.x])); +mesh.y = SmoothMeshLines( [CPW_width/2+[-edge_res/3 +edge_res/3*2] CPW_gap+CPW_width/2+[-edge_res/3*2 +edge_res/3]], edge_res , 1.5 ,0); +mesh.y = SmoothMeshLines( [0 mesh.y], edge_res*2, 1.3 ,0); +mesh.y = SmoothMeshLines( [0 mesh.y substrate_width/2 substrate_width/2+air_spacing], resolution, 1.3 ,0); +mesh.y = unique(sort([-mesh.y mesh.y])); +mesh.z = SmoothMeshLines( [-air_spacing linspace(0,substrate_thickness,5) substrate_thickness+air_spacing], resolution ); + +mesh = AddPML(mesh, pml_add_cells); +CSX = DefineRectGrid( CSX, unit, mesh ); + +%% substrate +CSX = AddMaterial( CSX, 'RO4350B' ); +CSX = SetMaterialProperty( CSX, 'RO4350B', 'Epsilon', substrate_epr ); +start = [-CPW_length/2, -substrate_width/2, 0]; +stop = [+CPW_length/2, +substrate_width/2, substrate_thickness]; +CSX = AddBox( CSX, 'RO4350B', 0, start, stop ); + +%% +CSX = AddMetal( CSX, 'CPW_PORT' ); + +%% CPW port, with the measurement plane at the end of each port +portstart = [ -CPW_length/2 , -CPW_width/2, substrate_thickness]; +portstop = [ -CPW_length/2+CPW_port_length, CPW_width/2, substrate_thickness]; +[CSX,port{1}] = AddCPWPort( CSX, 999, 1, 'CPW_PORT', portstart, portstop, CPW_gap, 'x', [0 1 0], 'ExcitePort', true, 'FeedShift', feed_shift_cells*resolution, 'MeasPlaneShift', CPW_port_length, 'Feed_R', feed_R); + +portstart = [ CPW_length/2 , -CPW_width/2, substrate_thickness]; +portstop = [ CPW_length/2-CPW_port_length, CPW_width/2, substrate_thickness]; +[CSX,port{2}] = AddCPWPort( CSX, 999, 2, 'CPW_PORT', portstart, portstop, CPW_gap, 'x', [0 1 0], 'MeasPlaneShift', CPW_port_length, 'Feed_R', feed_R); + +%% CPW +CSX = AddMetal( CSX, 'CPW'); +start = [ -CPW_length/2+CPW_port_length, -CPW_width/2, substrate_thickness]; +stop = [ +CPW_length/2-CPW_port_length, CPW_width/2, substrate_thickness]; +CSX = AddBox(CSX, 'CPW', 999, start, stop); + +%% CPW grounds +CSX = AddMetal( CSX, 'GND' ); +start = [-CPW_length/2, -CPW_width/2-CPW_gap, substrate_thickness]; +stop = [+CPW_length/2, -substrate_width/2 , substrate_thickness]; +CSX = AddBox(CSX, 'GND', 999, start, stop); + +start = [-CPW_length/2, +CPW_width/2+CPW_gap, substrate_thickness]; +stop = [+CPW_length/2, +substrate_width/2 , substrate_thickness]; +CSX = AddBox(CSX, 'GND', 999, start, stop); + +%% write/show/run the openEMS compatible xml-file +Sim_Path = 'tmp'; +Sim_CSX = 'CPW.xml'; + +[status, message, messageid] = rmdir( Sim_Path, 's' ); % clear previous directory +[status, message, messageid] = mkdir( Sim_Path ); % create empty simulation folder + +WriteOpenEMS( [Sim_Path '/' Sim_CSX], FDTD, CSX ); +CSXGeomPlot( [Sim_Path '/' Sim_CSX] ); +RunOpenEMS( Sim_Path, Sim_CSX ); + +%% post-processing +close all +f = linspace( 1e6, f_max, 1601 ); +port = calcPort( port, Sim_Path, f, 'RefImpedance', 50); + +s11 = port{1}.uf.ref./ port{1}.uf.inc; +s21 = port{2}.uf.ref./ port{1}.uf.inc; + +plot(f/1e9,20*log10(abs(s11)),'k-','LineWidth',2); +hold on; +grid on; +plot(f/1e9,20*log10(abs(s21)),'r--','LineWidth',2); +legend('S_{11}','S_{21}'); +ylabel('S-Parameter (dB)','FontSize',12); +xlabel('frequency (GHz) \rightarrow','FontSize',12); + + |