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Tutorials: Helix antenna using curve instead of wire 

Signed-off-by: Thorsten Liebig <Thorsten.Liebig@gmx.de>
pull/1/head
Thorsten Liebig 2013-02-13 13:58:19 +01:00
parent 1f285996fc
commit 62b2c1124c
1 changed files with 23 additions and 17 deletions
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40
matlab/Tutorials/Helical_Antenna.m
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@ -29,13 +29,12 @@ fc = 0.5e9; % 20 dB corner frequency
Helix.radius = 20; % --> diameter is ~ lambda/pi
Helix.turns = 10; % --> expected gain is G ~ 4 * 10 = 40 (16dBi)
Helix.pitch = 30; % --> pitch is ~ lambda/4
Helix.wire_rad = 1;
Helix.mesh_res = 3;
gnd.radius = lambda0/2;
% feeding
feed.width = 2; %feeding port width
feed.heigth = 2;
feed.heigth = 3;
feed.R = 120; %feed impedance
% size of the simulation box
@ -51,12 +50,21 @@ FDTD = SetBoundaryCond( FDTD, BC );
max_res = floor(c0 / (f0+fc) / unit / 20); % cell size: lambda/20
CSX = InitCSX();
mesh.x = [-SimBox(1)/2-gnd.radius -Helix.radius:Helix.wire_rad:Helix.radius SimBox(1)/2+gnd.radius];
mesh.x = SmoothMeshLines( mesh.x, max_res, 1.4); % create a smooth mesh between specified fixed mesh lines
% create helix mesh
mesh.x = SmoothMeshLines([-Helix.radius 0 Helix.radius],Helix.mesh_res);
% add the air-box
mesh.x = [mesh.x -SimBox(1)/2-gnd.radius SimBox(1)/2+gnd.radius];
% create a smooth mesh between specified fixed mesh lines
mesh.x = SmoothMeshLines( mesh.x, max_res, 1.4);
% copy x-mesh to y-direction
mesh.y = mesh.x;
mesh.z = unique([-SimBox(3)/2 0:Helix.wire_rad:(Helix.turns*Helix.pitch+feed.heigth+Helix.wire_rad) (feed.heigth+Helix.wire_rad+Helix.turns*Helix.pitch)+SimBox(3)/2 ]);
% create helix mesh in z-direction
mesh.z = SmoothMeshLines([0 feed.heigth Helix.turns*Helix.pitch+feed.heigth],Helix.mesh_res);
% add the air-box
mesh.z = unique([mesh.z -SimBox(3)/2 max(mesh.z)+SimBox(3)/2 ]);
% create a smooth mesh between specified fixed mesh lines
mesh.z = SmoothMeshLines( mesh.z, max_res, 1.4 );
CSX = DefineRectGrid( CSX, unit, mesh );
@ -72,7 +80,7 @@ coil_z = ang/2/pi*Helix.pitch;
helix.x=[];
helix.y=[];
helix.z=[];
zpos = feed.heigth+Helix.wire_rad;
zpos = feed.heigth;
for n=0:Helix.turns-1
helix.x = [helix.x coil_x];
helix.y = [helix.y coil_y];
@ -83,20 +91,18 @@ clear p
p(1,:) = helix.x;
p(2,:) = helix.y;
p(3,:) = helix.z;
CSX = AddWire(CSX, 'helix', 0, p, Helix.wire_rad);
start = [Helix.radius-feed.width/2 -feed.width/2 feed.heigth];
stop = [Helix.radius+feed.width/2 +feed.width/2 feed.heigth+2*Helix.wire_rad];
CSX = AddBox(CSX,'helix',0,start,stop);
CSX = AddCurve(CSX, 'helix', 0, p);
%% create ground (same size as substrate)
%% create ground circular ground
CSX = AddMetal( CSX, 'gnd' ); % create a perfect electric conductor (PEC)
start = [0 0 -0.1];
stop = [0 0 0.1];
CSX = AddCylinder(CSX,'gnd',10,start,stop,gnd.radius);
% add a box using cylindrical coordinates
start = [0 0 0];
stop = [gnd.radius 2*pi 0];
CSX = AddBox(CSX,'gnd',10,start,stop,'CoordSystem',1);
%% apply the excitation & resist as a current source
start = [Helix.radius-feed.width/2 -feed.width/2 0];
stop = [Helix.radius+feed.width/2 +feed.width/2 feed.heigth];
start = [Helix.radius 0 0];
stop = [Helix.radius 0 feed.heigth];
[CSX port] = AddLumpedPort(CSX, 5 ,1 ,feed.R, start, stop, [0 0 1], true);
%%nf2ff calc