1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
function [port nf2ff] = Patch_Antenna_Array(Sim_Path, postproc_only, show_structure, xpos, caps, resist, active )
% [port nf2ff] = Patch_Antenna_Array(Sim_Path, postproc_only, show_structure, xpos, caps, resist, active )
%
% Script to setup the patch array as described in [1].
% Run main script in Patch_Antenna_Phased_Array.m instead!
%
% Sim_Path: Simulation path
% postproc_only: set to post process only 0/1
% show_structure: show the strucuture in AppCSXCAD 0/1
% xpos: the x-position for each antenna is defined
% caps: the port capacity (will override active port)
% resist: port resitance
% active: switch port active
%
% References:
% [1] Y. Yusuf and X. Gong, “A low-cost patch antenna phased array with
% analog beam steering using mutual coupling and reactive loading,” IEEE
% Antennas Wireless Propag. Lett., vol. 7, pp. 81–84, 2008.
%
% Tested with
% - Matlab 2011a
% - openEMS v0.0.31
%
% (C) 2013 Thorsten Liebig <thorsten.liebig@gmx.de>
% example
% xpos = [-41 0 41];
% caps = [0.2e-12 0 0.2e-12];
% active = [0 1 0];
% resist = [50 50 50];
%% setup the simulation
physical_constants;
unit = 1e-3; % all length in mm
% patch geometry setup
patch.W = 35; % width
patch.L = 28.3; % length
patch.Ws = 3.8; % width of feeding stub
patch.Gs = 1; % width of feeding gab
patch.l = 6; % length of feeding stub
patch.y0 = 10; % depth of feeding stub into into patch
% patch resonance frequency
f0 = 3e9;
%substrate setup
substrate.name = 'Ro3003';
substrate.epsR = 3;
substrate.kappa = 0.0013 * 2*pi*f0 * EPS0*substrate.epsR;
substrate.thickness = 1.524;
substrate.cells = 4;
substrate.width = patch.W + max(xpos) - min(xpos) + 4*patch.l;
substrate.length = 3*patch.l + patch.L;
% size of the simulation box
AirSpacer = [50 50 30];
edge_res = [-1/3 2/3]*1;
%% setup FDTD parameter & excitation function
fc = 2e9; % 20 dB corner frequency
FDTD = InitFDTD( 'EndCriteria', 1e-4 );
FDTD = SetGaussExcite( FDTD, f0, fc );
BC = [1 1 1 1 1 1]*3;
FDTD = SetBoundaryCond( FDTD, BC );
%% setup CSXCAD geometry & mesh
CSX = InitCSX();
mesh.x = [];
mesh.y = [];
mesh.z = [];
%% create patch
CSX = AddMetal( CSX, 'patch' ); % create a perfect electric conductor (PEC)
for port_nr=1:numel(xpos)
start = [xpos(port_nr)-patch.W/2 patch.l substrate.thickness];
stop = [xpos(port_nr)-patch.Ws/2-patch.Gs patch.l+patch.L substrate.thickness];
CSX = AddBox(CSX,'patch',10, start, stop);
mesh.x = [mesh.x xpos(port_nr)-patch.W/2-edge_res];
start = [xpos(port_nr)+patch.W/2 patch.l substrate.thickness];
stop = [xpos(port_nr)+patch.Ws/2+patch.Gs patch.l+patch.L substrate.thickness];
CSX = AddBox(CSX,'patch',10, start, stop);
mesh.x = [mesh.x xpos(port_nr)+patch.W/2+edge_res];
mesh.y = [mesh.y patch.l-edge_res patch.l+patch.L+edge_res];
start = [xpos(port_nr)-patch.Ws/2-patch.Gs patch.l+patch.y0 substrate.thickness];
stop = [xpos(port_nr)+patch.Ws/2+patch.Gs patch.l+patch.L substrate.thickness];
CSX = AddBox(CSX,'patch',10, start, stop);
% feed line
start = [xpos(port_nr)-patch.Ws/2 patch.l+patch.y0 substrate.thickness];
stop = [xpos(port_nr)+patch.Ws/2 0 substrate.thickness];
CSX = AddBox(CSX,'patch',10, start, stop);
mesh.x = [mesh.x xpos(port_nr)+linspace(-patch.Ws/2-patch.Gs,-patch.Ws/2,3) xpos(port_nr)+linspace(patch.Ws/2,patch.Ws/2+patch.Gs,3)];
start = [xpos(port_nr)-patch.Ws/2 0 0];
stop = [xpos(port_nr)+patch.Ws/2 0 substrate.thickness];
if (caps(port_nr)>0)
CSX = AddLumpedElement(CSX, ['C_' num2str(port_nr)], 2, 'C', caps(port_nr));
CSX = AddBox(CSX,['C_' num2str(port_nr)],10, start, stop);
[CSX port{port_nr}] = AddLumpedPort(CSX, 5 ,port_nr ,inf, start, stop, [0 0 1], 0);
else
% feed port
[CSX port{port_nr}] = AddLumpedPort(CSX, 5 ,port_nr, resist(port_nr), start, stop, [0 0 1], active(port_nr));
end
end
%% create substrate
CSX = AddMaterial( CSX, substrate.name );
CSX = SetMaterialProperty( CSX, substrate.name, 'Epsilon', substrate.epsR, 'Kappa', substrate.kappa );
start = [-substrate.width/2 0 0];
stop = [ substrate.width/2 substrate.length substrate.thickness];
CSX = AddBox( CSX, substrate.name, 0, start, stop );
mesh.x = [mesh.x start(1) stop(1)];
mesh.y = [mesh.y start(2) stop(2)];
% add extra cells to discretize the substrate thickness
mesh.z = [linspace(0,substrate.thickness,substrate.cells+1) mesh.z];
%% create ground (same size as substrate)
CSX = AddMetal( CSX, 'gnd' ); % create a perfect electric conductor (PEC)
start(3)=0;
stop(3) =0;
CSX = AddBox(CSX,'gnd',10,start,stop);
%% finalize the mesh
% generate a smooth mesh with max. cell size: lambda_min / 20
mesh = SmoothMesh(mesh, 2, 1.3);
mesh.x = [mesh.x min(mesh.x)-AirSpacer(1) max(mesh.x)+AirSpacer(1)];
mesh.y = [mesh.y min(mesh.y)-AirSpacer(2) max(mesh.y)+AirSpacer(2)];
mesh.z = [mesh.z min(mesh.z)-AirSpacer(3) max(mesh.z)+2*AirSpacer(3)];
mesh = SmoothMesh(mesh, c0 / (f0+fc) / unit / 20, 1.3);
%% add a nf2ff calc box; size is 3 cells away from MUR boundary condition
start = [mesh.x(4) mesh.y(4) mesh.z(4)];
stop = [mesh.x(end-3) mesh.y(end-3) mesh.z(end-3)];
[CSX nf2ff] = CreateNF2FFBox(CSX, 'nf2ff', start, stop);
mesh = AddPML(mesh,(BC==3)*8);
CSX = DefineRectGrid(CSX, unit, mesh);
%% prepare simulation folder
Sim_CSX = 'patch_array.xml';
if (postproc_only==0)
[status, message, messageid] = rmdir( Sim_Path, 's' ); % clear previous directory
[status, message, messageid] = mkdir( Sim_Path ); % create empty simulation folder
%% write openEMS compatible xml-file
WriteOpenEMS( [Sim_Path '/' Sim_CSX], FDTD, CSX );
%% show the structure
if (show_structure>0)
CSXGeomPlot( [Sim_Path '/' Sim_CSX] );
end
%% run openEMS
RunOpenEMS( Sim_Path, Sim_CSX);
end
|
