Main Content

Design Variations On Microstrip Patch Antenna Using PCB Stack

Use the pcbstack to design basic, parasitic, direct-coupled, and CP patch antennas.

Setup parameters.

vp  = physconst('lightspeed');
f   = 850e6;
lambda = vp./f;

Design Basic Patch Antenna

Set the length and width of the patch and the groundplane.

Lp = lambda(1)/2;
Wp = lambda(1)/2;
Lgp = 0.75.*lambda(1);
Wgp = 0.75.*lambda(1);
h = 2.e-3; 
p1 = antenna.Rectangle('Length',Lp,'Width',Wp,'NumPoints',30);
p2 = antenna.Rectangle('Length',Lgp,'Width',Wgp);
d1 = dielectric('Air');

Define the properties of the PCB stack.

basicPatch = pcbStack;
basicPatch.Name = 'Basic Patch';
basicPatch.BoardThickness = h;
basicPatch.BoardShape = p2;
basicPatch.Layers = {p1,d1,p2};
basicPatch.FeedLocations = [-lambda(1)/8 0 1 3];
figure
show(basicPatch)

Figure contains an axes. The axes with title pcbStack antenna element contains 7 objects of type patch, surface. These objects represent PEC, feed.

Plot the impedance of the basic patch antenna.

freq1 = linspace(f(1)-0.05*f(1),f(1) + 0.05*f(1),51);
figure
impedance(basicPatch,freq1)

Figure contains an axes. The axes with title Impedance contains 2 objects of type line. These objects represent Resistance, Reactance.

Plot the radiation pattern of the basic patch antenna.

figure
pattern(basicPatch,f(1))

Figure contains an axes and other objects of type uicontrol. The axes contains 7 objects of type patch, surface.

Design Parasitic Patch Antenna

Set the dimensions for the patch.

L = 0.15;
W = 1.5*L;
stripL = L;
gapx = .015;
gapy = .01;
r1 = antenna.Rectangle('Center',[0,0],'Length',L,'Width',W);
r2 = antenna.Rectangle('Center',[L/2+stripL/2+gapx,0],'Length',stripL,'Width',W,'NumPoints',[2 20 2 20]);
r3 = antenna.Rectangle('Center',[-L/2-stripL/2-gapx,0],'Length',stripL,'Width',W,'NumPoints',[2 20 2 20]);
r = r1+r2+r3; 
figure
show(r)

Figure contains an axes. The axes contains 2 objects of type patch. This object represents PEC.

Set the dimensions of the groundplane.

Lgp = 0.55;
Wgp = 0.4;
g1  = antenna.Rectangle('Center',[0,0],'Length',Lgp,'Width',Wgp);

Define the properties of the PCB stack. Create a pcb stack by driving the center radiator.

parasitic_patch = pcbStack;
parasitic_patch.BoardShape = g1;
parasitic_patch.BoardThickness = .007;
parasitic_patch.Layers = {r,g1};
parasitic_patch.FeedLocations = [(L)/4 0 1 2];
figure
show(parasitic_patch)

Figure contains an axes. The axes with title pcbStack antenna element contains 7 objects of type patch, surface. These objects represent PEC, feed.

Plot the S-parameters of the parasitic patch antenna.

s = sparameters(parasitic_patch,linspace(0.8e9,1e9,11));
figure
rfplot(s)

Figure contains an axes. The axes contains an object of type line. This object represents dB(S_{11}).

Plot the radiation pattern of the parasitic patch antenna.

figure
pattern(parasitic_patch,0.896e9)

Figure contains an axes and other objects of type uicontrol. The axes contains 7 objects of type patch, surface.

Design Direct-coupled Patch Antenna

r2 = copy(r1);
r2.Center = [lambda/1.25,0];
r3 = copy(r1);
r3.Center = [-lambda/1.25,0];
r = r1+r2+r3;
figure
show(r)

Figure contains an axes. The axes contains 2 objects of type patch. This object represents PEC.

Strip join the sections.

r4 = antenna.Rectangle('Length',0.65*lambda,'Width',0.02*lambda,'Center',[lambda/2,0],'NumPoints',[20 2 20 2]);
r5 = copy(r4);
r5.Center = [-lambda/2,0];
s = r + r4 + r5;
figure
show(s)

Figure contains an axes. The axes contains 2 objects of type patch. This object represents PEC.

Define the properties of the PCB stack.

g1.Length = 0.8;
series_patch = pcbStack;
series_patch.BoardShape = g1;
series_patch.Layers = {s,g1};
series_patch.FeedLocations = [L/4 0 1 2];
figure
show(series_patch)

Figure contains an axes. The axes with title pcbStack antenna element contains 7 objects of type patch, surface. These objects represent PEC, feed.

Plot the radiation pattern at 1 GHz for the direct-coupled patch antenna.

figure
pattern(series_patch,1e9)

Figure contains an axes and other objects of type uicontrol. The axes contains 7 objects of type patch, surface.

Mesh the antenna using maximum edge length of 0.03 m. Plot the impedance of the direct-coupled patch antenna for the frequency range, 0.8 GHz to 1.2 GHz.

figure
mesh(series_patch,'MaxEdgeLength',0.03)

Figure contains an axes and other objects of type uicontrol. The axes with title Metal mesh contains 2 objects of type patch, surface.

figure
impedance(series_patch,linspace(0.8e9,1.2e9,81))

Figure contains an axes. The axes with title Impedance contains 2 objects of type line. These objects represent Resistance, Reactance.

Design Circularly Polarized Patch - Truncated Corners

Set the length and width of the patch and the groundplane.

Lp = lambda(1)/2;
Wp = lambda(1)/2;
Lgp = 0.75.*lambda(1);
Wgp = 0.75.*lambda(1);
h = 2.e-3;

Create the base shape for the patch.

p1 = antenna.Rectangle('Length',Lp,'Width',Wp,'NumPoints',20);

Truncate the corners of the rectangle.

Lcorner = 0.25*Lp;
Wcorner = 0.25*Wp;
cornerCenter1 = [-Lp/2,Wp/2,0];
cornerCenter2 = [Lp/2,-Wp/2,0];
pcorner1 = antenna.Rectangle('Length',Lcorner,'Width',Wcorner);
pcorner1 = rotateZ(pcorner1,45);
pcorner1 = translate(pcorner1,cornerCenter1);
pcorner2 = antenna.Rectangle('Length',Lcorner,'Width',Wcorner);
pcorner2 = rotateZ(pcorner2,45);
pcorner2 = translate(pcorner2,cornerCenter2);
pradiator = p1 -pcorner1-pcorner2;

Create the groundplane shape.

p2 = antenna.Rectangle('Length',Lgp,'Width',Wgp);

Define the dielectric Layer.

d1 = dielectric('Air');

Define the properties of the PCB stack for the circularly polarized patch.

truncatedCornerPatch = pcbStack;
truncatedCornerPatch.Name = 'Basic Patch';
truncatedCornerPatch.BoardThickness = h;
truncatedCornerPatch.BoardShape = p2;
truncatedCornerPatch.Layers = {pradiator,d1,p2};
truncatedCornerPatch.FeedLocations = [-lambda(1)/8 0 1 3];
figure
show(truncatedCornerPatch)

Figure contains an axes. The axes with title pcbStack antenna element contains 7 objects of type patch, surface. These objects represent PEC, feed.

Plot impedance of the circularly polarized antenna.

figure
impedance(truncatedCornerPatch,freq1)

Figure contains an axes. The axes with title Impedance contains 2 objects of type line. These objects represent Resistance, Reactance.

See Also