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Design Variations of Microstrip Patch Antenna Using PCB Stack

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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;
d1.Thickness = h;
basicPatch.BoardShape = p2;
basicPatch.Layers = {p1,d1,p2};
basicPatch.FeedLocations = [-lambda(1)/8 0 1 3];
figure
show(basicPatch)

Figure contains an axes object. The axes object with title pcbStack antenna element, xlabel x (mm), ylabel y (mm) 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 object. The axes object with title Impedance, xlabel Frequency (MHz), ylabel Impedance (ohms) 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 2 axes objects and other objects of type uicontrol. Axes object 1 contains 7 objects of type patch, surface. Hidden axes object 2 contains 19 objects of type surface, line, text, patch.

Design Parasitic Patch Antenna

Set the dimensions for the patch.

L = 0.15;
W = 1.5*L;
stripL = L;
gapx = 0.015;
gapy = 0.01;
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 object. The axes object with xlabel x (mm), ylabel y (mm) contains 2 objects of type patch. These objects represent PEC, mypolygon.

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 = 0.007;
parasitic_patch.Layers = {r,g1};
parasitic_patch.FeedLocations = [(L)/4 0 1 2];
figure
show(parasitic_patch)

Figure contains an axes object. The axes object with title pcbStack antenna element, xlabel x (mm), ylabel y (mm) 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 object. The axes object with xlabel Frequency (GHz), ylabel Magnitude (dB) 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 2 axes objects and other objects of type uicontrol. Axes object 1 contains 7 objects of type patch, surface. Hidden axes object 2 contains 19 objects of type surface, line, text, patch.

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 object. The axes object with xlabel x (mm), ylabel y (mm) contains 2 objects of type patch. These objects represent PEC, mypolygon.

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 object. The axes object with xlabel x (mm), ylabel y (mm) contains 2 objects of type patch. These objects represent PEC, mypolygon.

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 object. The axes object with title pcbStack antenna element, xlabel x (mm), ylabel y (mm) 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 2 axes objects and other objects of type uicontrol. Axes object 1 contains 7 objects of type patch, surface. Hidden axes object 2 contains 19 objects of type surface, line, text, patch.

Mesh the antenna using maximum edge length of 0.03 m. 

figure
mesh(series_patch, MaxEdgeLength=0.03)

Figure contains an axes object and an object of type uicontrol. The axes object with title Metal mesh, xlabel x (m), ylabel y (m) contains 2 objects of type patch, surface. These objects represent PEC, feed.

Plot the impedance of the direct-coupled patch antenna for the frequency range, 0.8 GHz to 1.2 GHz.

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

Figure contains an axes object. The axes object with title Impedance, xlabel Frequency (GHz), ylabel Impedance (ohms) 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;
d1.Thickness = h;
truncatedCornerPatch.BoardShape = p2;
truncatedCornerPatch.Layers = {pradiator,d1,p2};
truncatedCornerPatch.FeedLocations = [-lambda(1)/8 0 1 3];
figure
show(truncatedCornerPatch)

Figure contains an axes object. The axes object with title pcbStack antenna element, xlabel x (mm), ylabel y (mm) 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 object. The axes object with title Impedance, xlabel Frequency (MHz), ylabel Impedance (ohms) contains 2 objects of type line. These objects represent Resistance, Reactance.

See Also