120 lines
4.0 KiB
Matlab
120 lines
4.0 KiB
Matlab
close all
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clear
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clc
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%% setup the simulation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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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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EPS0 = 8.85418781762e-12;
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MUE0 = 1.256637062e-6;
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C0 = 1/sqrt(EPS0*MUE0);
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Z0 = sqrt(MUE0/EPS0);
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f0 = 0.5e9;
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epsR = 1;
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%% define openEMS options %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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openEMS_opts = '';
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% openEMS_opts = [openEMS_opts ' --debug-material'];
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% openEMS_opts = [openEMS_opts ' --debug-operator'];
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% openEMS_opts = [openEMS_opts ' --disable-dumps --engine=fastest'];
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openEMS_opts = [openEMS_opts ' --engine=fastest'];
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Sim_Path = 'tmp';
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Sim_CSX = 'coax.xml';
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if (exist(Sim_Path,'dir'))
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rmdir(Sim_Path,'s');
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end
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mkdir(Sim_Path);
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%% setup FDTD parameter & excitation function %%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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FDTD = InitFDTD(5e5,1e-5);
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FDTD = SetGaussExcite(FDTD,f0,f0);
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BC = [0 0 0 0 0 0]; %electric walls only
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FDTD = SetBoundaryCond(FDTD,BC);
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%% setup CSXCAD geometry & mesh %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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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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CSX = DefineRectGrid(CSX, 1e-3,mesh);
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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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CSX = AddMaterial(CSX,'copper');
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CSX = SetMaterialProperty(CSX,'copper','Kappa',56e6);
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start = [0, 0 , 0];stop = [0, 0 , length];
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CSX = AddCylinder(CSX,'copper',0 ,start,stop,coax_rad_i);
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CSX = AddCylindricalShell(CSX,'copper',0 ,start,stop,0.5*(coax_rad_aa+coax_rad_ai),(coax_rad_aa-coax_rad_ai));
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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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%% apply the excitation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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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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%% define dump boxes... %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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CSX = AddDump(CSX,'Et_','DumpMode',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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CSX = AddDump(CSX,'Ht_','DumpType',1,'DumpMode',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_1',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_1', 0 ,start,stop);
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CSX = AddProbe(CSX,'ut1_2',0);
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start = [ coax_rad_i 0 length/2+mesh_res(3) ];stop = [ coax_rad_ai 0 length/2+mesh_res(3) ];
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CSX = AddBox(CSX,'ut1_2', 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 compatoble 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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RunOpenEMS(Sim_Path,Sim_CSX,openEMS_opts);
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%% postproc & do the plots %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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UI = ReadUI({'ut1_1','ut1_2','it1'},Sim_Path);
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u_f = (UI.FD{1}.val + UI.FD{2}.val)/2; %averaging voltages to fit current
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i_f = UI.FD{3}.val;
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ZL = Z0/2/pi/sqrt(epsR)*log(coax_rad_ai/coax_rad_i); %analytic line-impedance of a coax
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plot(UI.FD{1}.f,ZL*ones(size(u_f)),'g');
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hold on;
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grid on;
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Z = u_f./i_f;
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plot(UI.FD{1}.f,real(Z),'Linewidth',2);
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plot(UI.FD{1}.f,imag(Z),'r','Linewidth',2);
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xlim([0 2*f0]);
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legend('Z_L','\Re\{Z\}','\Im\{Z\}','Location','Best');
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