156 lines
4.1 KiB
Matlab
156 lines
4.1 KiB
Matlab
function pass = Coax
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physical_constants;
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ENABLE_PLOTS = 1;
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CLEANUP = 1; % if enabled and result is PASS, remove simulation folder
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STOP_IF_FAILED = 1; % if enabled and result is FAILED, stop with error
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% LIMITS
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upper_error = 0.036; % max +3.6%
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lower_error = 0; % max -0.0%
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% structure
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abs_length = 250;
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length = 1000;
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coax_rad_i = 100;
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coax_rad_ai = 230;
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coax_rad_aa = 240;
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mesh_res = [5 5 5];
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f_start = 0;
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f_stop = 1e9;
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Sim_Path = 'tmp';
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Sim_CSX = 'coax.xml';
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[status,message,messageid]=rmdir(Sim_Path,'s');
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[status,message,messageid]=mkdir(Sim_Path);
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%setup FDTD parameter
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FDTD = InitFDTD(5e5,1e-6);
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FDTD = SetGaussExcite(FDTD,(f_stop-f_start)/2,(f_stop-f_start)/2);
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BC = [1 1 1 1 1 1] * 0;
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FDTD = SetBoundaryCond(FDTD,BC);
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%setup CSXCAD geometry
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CSX = InitCSX();
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mesh.x = -2.5*mesh_res(1)-coax_rad_aa : mesh_res(1) : coax_rad_aa+2.5*mesh_res(1);
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mesh.y = mesh.x;
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mesh.z = 0 : mesh_res(3) : length;
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mesh.z = linspace(0,length,numel(mesh.z) + 4-mod(numel(mesh.z),4)); % make it compatible with sse-engine
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CSX = DefineRectGrid(CSX, 1e-3,mesh);
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%create copper
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CSX = AddMetal(CSX,'PEC');
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%%%fake pml
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finalKappa = 0.3/abs_length^4;
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finalSigma = finalKappa*MUE0/EPS0;
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CSX = AddMaterial(CSX,'pml');
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CSX = SetMaterialProperty(CSX,'pml','Kappa',finalKappa);
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CSX = SetMaterialProperty(CSX,'pml','Sigma',finalSigma);
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CSX = SetMaterialWeight(CSX,'pml','Kappa',['pow(abs(z)-' num2str(length-abs_length) ',4)']);
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CSX = SetMaterialWeight(CSX,'pml','Sigma',['pow(abs(z)-' num2str(length-abs_length) ',4)']);
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%%% coax
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start = [0, 0 , 0];stop = [0, 0 , length];
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CSX = AddCylinder(CSX,'PEC',0 ,start,stop,coax_rad_i); % inner conductor
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CSX = AddCylindricalShell(CSX,'PEC',0 ,start,stop,0.5*(coax_rad_aa+coax_rad_ai),(coax_rad_aa-coax_rad_ai)); % outer conductor
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%%% add PML
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start(3) = length-abs_length;
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CSX = AddCylindricalShell(CSX,'pml',0 ,start,stop,0.5*(coax_rad_i+coax_rad_ai),(coax_rad_ai-coax_rad_i));
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start(3) = 0; stop(3)=mesh_res(1)/2;
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CSX = AddExcitation(CSX,'excite',0,[1 1 0]);
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weight{1} = '(x)/(x*x+y*y)';
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weight{2} = 'y/pow(rho,2)';
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weight{3} = '0';
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CSX = SetExcitationWeight(CSX, 'excite', weight );
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CSX = AddCylindricalShell(CSX,'excite',0 ,start,stop,0.5*(coax_rad_i+coax_rad_ai),(coax_rad_ai-coax_rad_i));
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% %dump
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% CSX = AddDump(CSX,'Et_',0,2);
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% start = [mesh.x(1) , 0 , mesh.z(1)];
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% stop = [mesh.x(end) , 0 , mesh.z(end)];
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% CSX = AddBox(CSX,'Et_',0 , start,stop);
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%
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% CSX = AddDump(CSX,'Ht_',1,2);
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% CSX = AddBox(CSX,'Ht_',0,start,stop);
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%voltage calc
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CSX = AddProbe(CSX,'ut1',0);
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start = [ coax_rad_i 0 length/2 ];stop = [ coax_rad_ai 0 length/2 ];
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CSX = AddBox(CSX,'ut1', 0 ,start,stop);
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%current calc
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CSX = AddProbe(CSX,'it1',1);
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mid = 0.5*(coax_rad_i+coax_rad_ai);
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start = [ -mid -mid length/2 ];stop = [ mid mid length/2 ];
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CSX = AddBox(CSX,'it1', 0 ,start,stop);
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%Write openEMS compatible xml-file
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WriteOpenEMS([Sim_Path '/' Sim_CSX],FDTD,CSX);
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%cd to working dir and run openEMS
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savePath = pwd();
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cd(Sim_Path); %cd to working dir
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invoke_openEMS( Sim_CSX );
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UI = ReadUI( {'ut1','it1'} );
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cd(savePath);
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%
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% analysis
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%
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f = UI.FD{2}.f;
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u = UI.FD{1}.val;
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i = UI.FD{2}.val;
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f_idx_start = interp1( f, 1:numel(f), f_start, 'nearest' );
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f_idx_stop = interp1( f, 1:numel(f), f_stop, 'nearest' );
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f = f(f_idx_start:f_idx_stop);
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u = u(f_idx_start:f_idx_stop);
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i = i(f_idx_start:f_idx_stop);
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Z = abs(u./i);
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% analytic formular for characteristic impedance
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Z0 = sqrt(MUE0/EPS0) * log(coax_rad_ai/coax_rad_i) / (2*pi);
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upper_limit = Z0 * (1+upper_error);
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lower_limit = Z0 * (1-lower_error);
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if ENABLE_PLOTS
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upper = upper_limit * ones(1,size(Z,2));
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lower = lower_limit * ones(1,size(Z,2));
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Z0_plot = Z0 * ones(1,size(Z,2));
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figure
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plot(f/1e9,[Z;upper;lower])
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hold on
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plot(f/1e9,Z0_plot,'m-.','LineWidth',2)
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hold off
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xlabel('Frequency (GHz)')
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ylabel('Impedance (Ohm)')
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legend( {'sim', 'upper limit', 'lower limit', 'theoretical'} );
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end
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pass = check_limits( Z, upper_limit, lower_limit );
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if pass
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disp( 'combinedtests/Coax.m (characteristic impedance): pass' );
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else
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disp( 'combinedtests/Coax.m (characteristic impedance): * FAILED *' );
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end
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if pass && CLEANUP
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rmdir( Sim_Path, 's' );
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end
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if ~pass && STOP_IF_FAILED
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error 'test failed';
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end
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