154 lines
4.4 KiB
Matlab
154 lines
4.4 KiB
Matlab
%
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% infinitesimal dipole example
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%
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close all
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clear
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clc
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postprocessing_only = 0;
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physical_constants
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% setup the simulation
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drawingunit = 1e-6; % specify everything in um
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Sim_Path = 'tmp';
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Sim_CSX = 'tmp.xml';
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f_max = 1e9;
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lambda = c0/f_max;
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% setup geometry values
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dipole_length = lambda/50 /drawingunit;
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dipole_orientation = 3; % 1,2,3: x,y,z
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CSX = InitCSX();
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% create an equidistant mesh
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mesh.x = -dipole_length*10:dipole_length/2:dipole_length*10;
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mesh.y = -dipole_length*10:dipole_length/2:dipole_length*10;
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mesh.z = -dipole_length*10:dipole_length/2:dipole_length*10;
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% excitation
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ex_vector = [0 0 0];
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ex_vector(dipole_orientation) = 1;
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start = ex_vector * -dipole_length/2;
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stop = ex_vector * dipole_length/2;
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CSX = AddExcitation( CSX, 'infDipole', 1, ex_vector );
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CSX = AddBox( CSX, 'infDipole', 1, start, stop );
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% NFFF contour
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start = [mesh.x(1) mesh.y(1) mesh.z(1) ]
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stop = [mesh.x(end) mesh.y(end) mesh.z(end) ]
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[CSX nf2ff] = CreateNF2FFBox(CSX, 'nf2ff', start, stop);
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% add space for PML
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mesh = AddPML( mesh, [8 8 8 8 8 8] );
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% define the mesh
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CSX = DefineRectGrid( CSX, drawingunit, mesh );
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if ~postprocessing_only
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% setup FDTD parameters & excitation function
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max_timesteps = 2000;
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min_decrement = 1e-6;
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FDTD = InitFDTD( max_timesteps, min_decrement, 'OverSampling',10 );
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FDTD = SetGaussExcite( FDTD, f_max/2, f_max/2 );
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BC = {'PML_8' 'PML_8' 'PML_8' 'PML_8' 'PML_8' 'PML_8'};
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FDTD = SetBoundaryCond( FDTD, BC );
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% Write openEMS compatible xml-file
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[~,~,~] = rmdir(Sim_Path,'s');
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[~,~,~] = mkdir(Sim_Path);
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WriteOpenEMS([Sim_Path '/' Sim_CSX],FDTD,CSX);
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% define openEMS options and start simulation
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openEMS_opts = '';
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RunOpenEMS( Sim_Path, Sim_CSX, openEMS_opts );
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end
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%% post processing
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disp( ' ' );
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disp( ' ********************************************************** ' );
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disp( ' ' );
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% calculate the far field at phi=0 degrees and at phi=90 degrees
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thetaRange = 0:2:359;
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r = 1; % evaluate fields at radius r
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disp( 'calculating far field at phi=[0 90] deg..' );
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[E_far_theta,E_far_phi,Prad,Dmax] = AnalyzeNF2FF( Sim_Path, nf2ff, f_max, thetaRange, [0 90], r );
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% display power and directivity
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disp( ['radiated power: Prad = ' num2str(Prad)] );
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disp( ['directivity: Dmax = ' num2str(Dmax)] );
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% calculate the e-field magnitude for phi = 0 deg
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E_phi0_far = zeros(1,numel(thetaRange));
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for n=1:numel(thetaRange)
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E_phi0_far(n) = norm( [E_far_theta(n,1) E_far_phi(n,1)] );
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end
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% display polar plot
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figure
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polar( thetaRange/180*pi, E_phi0_far );
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ylabel( 'theta / deg' );
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title( ['electrical far field (V/m) @r=' num2str(r) ' m phi=0 deg'] );
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legend( 'e-field magnitude', 'Location', 'BestOutside' );
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% calculate the e-field magnitude for phi = 90 deg
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E_phi90_far = zeros(1,numel(thetaRange));
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for n=1:numel(thetaRange)
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E_phi90_far(n) = norm([E_far_theta(n,2) E_far_phi(n,2)]);
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end
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% display polar plot
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figure
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polar( thetaRange/180*pi, E_phi90_far );
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ylabel( 'theta / deg' );
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title( ['electrical far field (V/m) @r=' num2str(r) ' m phi=90 deg'] );
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legend( 'e-field magnitude', 'Location', 'BestOutside' );
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% calculate the far field at theta=90 degrees
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phiRange = 0:2:359;
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r = 1; % evaluate fields at radius r
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disp( 'calculating far field at theta=90 deg..' );
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[E_far_theta,E_far_phi] = AnalyzeNF2FF( Sim_Path, nf2ff, f_max, 90, phiRange, r );
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E_theta90_far = zeros(1,numel(phiRange));
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for n=1:numel(phiRange)
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E_theta90_far(n) = norm([E_far_theta(1,n) E_far_phi(1,n)]);
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end
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% display polar plot
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figure
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polar( phiRange/180*pi, E_theta90_far );
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ylabel( 'phi / deg' );
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title( ['electrical far field (V/m) @r=' num2str(r) ' m theta=90 deg'] );
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legend( 'e-field magnitude', 'Location', 'BestOutside' );
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% calculate 3D pattern
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phiRange = 0:15:360;
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thetaRange = 0:10:180;
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r = 1; % evaluate fields at radius r
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disp( 'calculating 3D far field...' );
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[E_far_theta,E_far_phi] = AnalyzeNF2FF( Sim_Path, nf2ff, f_max, thetaRange, phiRange, r );
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E_far = sqrt( abs(E_far_theta).^2 + abs(E_far_phi).^2 );
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E_far_normalized = E_far / max(E_far(:));
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[theta,phi] = ndgrid(thetaRange/180*pi,phiRange/180*pi);
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x = E_far_normalized .* sin(theta) .* cos(phi);
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y = E_far_normalized .* sin(theta) .* sin(phi);
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z = E_far_normalized .* cos(theta);
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figure
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surf( x,y,z, E_far_normalized );
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axis equal
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xlabel( 'x' );
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ylabel( 'y' );
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zlabel( 'z' );
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%
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DumpFF2VTK([Sim_Path '/FF_pattern.vtk'],E_far_normalized, thetaRange, phiRange);
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disp(['view the farfield pattern "' Sim_Path '/FF_pattern.vtk" using paraview' ]);
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