new tutorial: CRLH Leaky Wave Antenna
Thorsten Liebig
parent
9f0799bbc2
commit
1e52c6b444
|
|
@ -0,0 +1,219 @@
|
|||
%
|
||||
% Tutorials / CRLH_LeakyWaveAnt
|
||||
%
|
||||
% Describtion at:
|
||||
% http://openems.de/index.php/Tutorial:_CRLH_Leaky_Wave_Antenna
|
||||
%
|
||||
% Tested with
|
||||
% - Matlab 2009b
|
||||
% - openEMS v0.0.23
|
||||
%
|
||||
% (C) 2011 Thorsten Liebig <thorsten.liebig@gmx.de>
|
||||
|
||||
close all
|
||||
clear
|
||||
clc
|
||||
|
||||
%% setup the simulation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
||||
physical_constants;
|
||||
unit = 1e-6; % specify everything in um
|
||||
|
||||
feed_length = 20000;
|
||||
|
||||
substrate_thickness = [1524 101 254];
|
||||
substrate_epr = [3.48 3.48 3.48];
|
||||
|
||||
N_Cells = 8; %number of CRLH unit cells
|
||||
|
||||
CRLH.LL = 14e3; %CRLH totel (line) length
|
||||
CRLH.LW = 4e3; %CRLH unit cell width (without the stubs)
|
||||
CRLH.GLB = 1950; %CRLH gap width bottom layer
|
||||
CRLH.GLT = 4700; %CRLH gap width top layer
|
||||
CRLH.SL = 7800; %CRLH stub length (bottom layer, both sides)
|
||||
CRLH.SW = 1000; %CRLH stub width (bottom layer, both sides)
|
||||
CRLH.VR = 250; %CRLH via hole radius (stub -> ground)
|
||||
CRLH.TopSig = sum(substrate_thickness); %top layer height
|
||||
CRLH.BottomSig = CRLH.TopSig - substrate_thickness(end); %bottom layer height
|
||||
|
||||
substrate_width = CRLH.LW + 2*CRLH.SL;
|
||||
Air_Spacer = 25000;
|
||||
|
||||
% frequency range of interest
|
||||
f_start = 0.8e9;
|
||||
f_stop = 6e9;
|
||||
|
||||
f_rad = (1.9:0.1:4.2)*1e9;
|
||||
|
||||
Plot_3D_Rad_Pattern = 0; %this may take a very very long time! > 7h
|
||||
|
||||
%% setup FDTD parameters & excitation function %%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
||||
FDTD = InitFDTD( 20000, 1e-6, 'OverSampling', 10 );
|
||||
FDTD = SetGaussExcite( FDTD, (f_start+f_stop)/2, (f_stop-f_start)/2 );
|
||||
BC = {'PML_8' 'PML_8' 'PML_8' 'PML_8' 'PML_8' 'PML_8'};
|
||||
FDTD = SetBoundaryCond( FDTD, BC );
|
||||
|
||||
%% Setup a basic mesh and create the CRLH unit cell
|
||||
CSX = InitCSX();
|
||||
resolution = c0/(f_stop*sqrt(max(substrate_epr)))/unit /30; % resolution of lambda/30
|
||||
|
||||
mesh.x = [-feed_length-(N_Cells*CRLH.LL)/2-Air_Spacer -feed_length-(N_Cells*CRLH.LL)/2 0 feed_length+(N_Cells*CRLH.LL)/2 feed_length+(N_Cells*CRLH.LL)/2+Air_Spacer];
|
||||
mesh.y = [-Air_Spacer-substrate_width/2 0 Air_Spacer+substrate_width/2];
|
||||
substratelines = cumsum(substrate_thickness);
|
||||
mesh.z = [-0.7*Air_Spacer 0 cumsum(substrate_thickness) linspace(substratelines(end-1),substratelines(end),4) Air_Spacer];
|
||||
|
||||
% create the CRLH unit cells (will define additional fixed mesh lines)
|
||||
pos_x = -(N_Cells*CRLH.LL)/2 + CRLH.LL/2;
|
||||
for n=1:N_Cells
|
||||
[CSX mesh] = CreateCRLH(CSX, mesh, CRLH, resolution/4, [pos_x 0 0]);
|
||||
pos_x = pos_x + CRLH.LL;
|
||||
end
|
||||
|
||||
% Smooth the given mesh
|
||||
mesh.x = SmoothMeshLines(mesh.x, resolution, 1.5, 0);
|
||||
mesh.y = SmoothMeshLines(mesh.y, resolution, 1.5, 0);
|
||||
mesh.z = SmoothMeshLines(mesh.z, resolution, 1.5, 0);
|
||||
CSX = DefineRectGrid( CSX, unit, mesh );
|
||||
|
||||
%% Setup the substrate layer
|
||||
substratelines = [0 substratelines];
|
||||
for n=1:numel(substrate_thickness)
|
||||
CSX = AddMaterial( CSX, ['substrate' int2str(n)] );
|
||||
CSX = SetMaterialProperty( CSX, ['substrate' int2str(n)], 'Epsilon', substrate_epr(n) );
|
||||
start = [-feed_length-(N_Cells*CRLH.LL)/2, -substrate_width/2, substratelines(n)];
|
||||
stop = [+feed_length+(N_Cells*CRLH.LL)/2, substrate_width/2, substratelines(n+1)];
|
||||
CSX = AddBox( CSX, ['substrate' int2str(n)], 0, start, stop );
|
||||
end
|
||||
|
||||
%% add the feeding MSL ports
|
||||
%ground plane
|
||||
CSX = AddMetal( CSX, 'ground' );
|
||||
start = [-feed_length-(N_Cells*CRLH.LL)/2, -substrate_width/2, 0];
|
||||
stop = [+feed_length+(N_Cells*CRLH.LL)/2, substrate_width/2, 0];
|
||||
CSX = AddBox( CSX, 'ground', 0, start, stop );
|
||||
|
||||
CSX = AddMetal( CSX, 'PEC' );
|
||||
portstart = [ -feed_length-(N_Cells*CRLH.LL)/2 , -CRLH.LW/2, substratelines(end)];
|
||||
portstop = [ -(N_Cells*CRLH.LL)/2, CRLH.LW/2, 0];
|
||||
[CSX,portstruct{1}] = AddMSLPort( CSX, 999, 1, 'PEC', portstart, portstop, 0, [0 0 -1], 'ExcitePort', 'excite', 'MeasPlaneShift', feed_length/2, 'Feed_R', 50);
|
||||
|
||||
portstart = [ feed_length+(N_Cells*CRLH.LL)/2 , -CRLH.LW/2, substratelines(end)];
|
||||
portstop = [ +(N_Cells*CRLH.LL)/2, CRLH.LW/2, 0];
|
||||
[CSX,portstruct{2}] = AddMSLPort( CSX, 999, 2, 'PEC', portstart, portstop, 0, [0 0 -1], 'MeasPlaneShift', feed_length/2, 'Feed_R', 50 );
|
||||
|
||||
|
||||
%% nf2ff calc
|
||||
start = [mesh.x(1) mesh.y(1) mesh.z(1) ] + 10*resolution;
|
||||
stop = [mesh.x(end) mesh.y(end) mesh.z(end)] - 10*resolution;
|
||||
[CSX nf2ff] = CreateNF2FFBox(CSX, 'nf2ff', start, stop);
|
||||
|
||||
%% write/show/run the openEMS compatible xml-file
|
||||
Sim_Path = 'tmp';
|
||||
Sim_CSX = 'CRLH.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] );
|
||||
return
|
||||
RunOpenEMS( Sim_Path, Sim_CSX );
|
||||
|
||||
%% post-processing
|
||||
close all
|
||||
f = linspace( f_start, f_stop, 1601 );
|
||||
port{1} = calcPort( portstruct{1}, Sim_Path, f, 'RefPlaneShift', feed_length*unit);
|
||||
port{2} = calcPort( portstruct{2}, Sim_Path, f, 'RefPlaneShift', feed_length*unit);
|
||||
|
||||
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);
|
||||
l = legend('S_{11}','S_{21}','Location','Best');
|
||||
set(l,'FontSize',12);
|
||||
ylabel('S-Parameter (dB)','FontSize',12);
|
||||
xlabel('frequency (GHz) \rightarrow','FontSize',12);
|
||||
ylim([-40 2]);
|
||||
|
||||
|
||||
%% NFFF contour plots %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|
||||
thetaRange = (0:3:359) - 180;
|
||||
for n=1:numel(f_rad)
|
||||
f_res = f_rad(n)
|
||||
% calculate the far field at phi=0 degrees and at phi=90 degrees
|
||||
r = 1; % evaluate fields at radius r
|
||||
disp( 'calculating far field at phi=[0 90] deg...' );
|
||||
[E_far_theta{n},E_far_phi{n},Prad(n),Dmax(n)] = AnalyzeNF2FF( Sim_Path, nf2ff, f_res, thetaRange, 0, r );
|
||||
toc
|
||||
end
|
||||
|
||||
%%
|
||||
Dlog=10*log10(Dmax);
|
||||
figure
|
||||
thetaRange = (0:3:359) - 180;
|
||||
for n=1:numel(f_rad)
|
||||
f_res = f_rad(n)
|
||||
|
||||
% display power and directivity
|
||||
disp( ['radiated power: Prad = ' num2str(Prad(n)) ' Watt']);
|
||||
disp( ['directivity: Dmax = ' num2str(Dlog(n)) ' dBi'] );
|
||||
|
||||
% calculate the e-field magnitude for phi = 0 deg
|
||||
E_phi0_far{n} = zeros(1,numel(thetaRange));
|
||||
for m=1:numel(thetaRange)
|
||||
E_phi0_far{n}(m) = norm( [E_far_theta{n}(m,1) E_far_phi{n}(m,1)] );
|
||||
end
|
||||
|
||||
E_phi0_far_log{n} = 20*log10(abs(E_phi0_far{n})/max(abs(E_phi0_far{n})));
|
||||
E_phi0_far_log{n} = E_phi0_far_log{n} + Dlog(n);
|
||||
|
||||
% display polar plot
|
||||
plot( thetaRange, E_phi0_far_log{n} ,'k-' );
|
||||
xlabel( 'theta (deg)' );
|
||||
ylabel( 'directivity (dBi)');
|
||||
grid on;
|
||||
ylim([-20 10]);
|
||||
pause(0.5)
|
||||
end
|
||||
|
||||
if (Plot_3D_Rad_Pattern==0)
|
||||
return
|
||||
end
|
||||
|
||||
%% calculate 3D pattern
|
||||
for n=1:numel(f_rad)
|
||||
f_res = f_rad(n);
|
||||
phiRange = 0:3:360;
|
||||
thetaRange = 0:3:180;
|
||||
r = 1; % evaluate fields at radius r
|
||||
disp( 'calculating 3D far field...' );
|
||||
[E_far_theta_3D{n},E_far_phi_3D{n}] = AnalyzeNF2FF( Sim_Path, nf2ff, f_res, thetaRange, phiRange, r );
|
||||
end
|
||||
|
||||
%%
|
||||
figure
|
||||
for n=1:numel(f_rad)
|
||||
f_res = f_rad(n);
|
||||
|
||||
E_far_3D{n} = sqrt( abs(E_far_theta_3D{n}).^2 + abs(E_far_phi_3D{n}).^2 );
|
||||
E_far_normalized_3D{n} = E_far_3D{n} / max(E_far_3D{n}(:)) * max(Dmax);
|
||||
|
||||
[theta,phi] = ndgrid(thetaRange/180*pi,phiRange/180*pi);
|
||||
x = E_far_normalized_3D{n} .* sin(theta) .* cos(phi);
|
||||
y = E_far_normalized_3D{n} .* sin(theta) .* sin(phi);
|
||||
z = E_far_normalized_3D{n} .* cos(theta);
|
||||
surf( x,y,z, E_far_normalized_3D{n},'EdgeColor','none');
|
||||
caxis([0 max(Dmax)]);
|
||||
axis equal
|
||||
xlabel( 'x' );
|
||||
xlim([-6 6]);
|
||||
ylabel( 'y' );
|
||||
ylim([-6 6]);
|
||||
zlabel( 'z' );
|
||||
zlim([-4 10]);
|
||||
title(['f=' num2str(f_res*1e-9,3) 'GHz - D=' num2str(Dlog(n),3) 'dBi'],'FontSize',12)
|
||||
pause(0.5)
|
||||
end
|
||||
|
||||
Loading…
Reference in New Issue