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8/11/2019 Antenna Lab3
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Peoples Democratic Republic of Algeria
Ministry of Higher Education and Scientific Research
University MHamed BOUGARA Boumerdes
Institute of Electrical and Electronic Engineering
Department of Electronics
Lab Report of the Degree of
MASTER 02
InElectrical and Electronic Engineering
Telecommunication Option
Title:
APERTURE ANTENNAS
Presented By:

Gassab Oussama
 Gacem BelQassim
Supervisor:
Dr. CHALLAL Mouloud
5/05/2014
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Abstract
In this small work our purpose is to analysis the aperture antenna
and its parameters under the concept of dimensions and the wavelength
ratio . and see how the radiation behave when this ratio is changed from
lower to higher values .
After that we will explain this results physically by using the
concepts of diffraction and scattering phenomena at the wall edges of the
aperture antenna.
By using MATLAB we simulate the results and we see if they
matches the theoretical concept or not .
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introduction:
this world contains very amazing fundamental concepts , which
occur under highly organized manner can be formulated mathematically.
Every physical concept that happens in this world can be understand it by
using mathematical formulas . the electromagnetic theory is very
important concepts in the field of physics and it is fundamental reality in
the field of communication ( antennas transmission , radar , ) .
the electromagnetic theory describes how the electric and magnetic
fields interact with itselfs and how they interact with time and space ; the
interaction with time and space contains the concept of the wave
propagation , and the concept of the relativistic between time , space , and
energy contains the concept of relativistic theory (( Einstein's relativistic
theory )) and all concepts of electromagnetic theory are described by
Maxwell equations.
the communication antennas are devices that transmit and receive
electromagnetic waves , the purpose of building antennas is to make thetheory of electromagnetic under human control in order to enhance
science and technologies and make our life easy in all different fields. To
do all this we have to build antennas with some specified parameters and
with high performance.
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1Theoretical Concepts
The Rectangular aperture antennas.
The circular aperture antennas.
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1.1 The Rectangular aperture antennas.
the electric field of the rectangular aperture on
ground plane is given by ( at far field region)
= 0 = 02 = 02
And the magnetic field is given by
= 0 = =
where = 2 sin = 2
sin
The electric field of rectangular in freespace is given by
= 0 = 04 1 + = 04 (1 + ) Because the fields containing nonfundamental function which they
haven't antiderivatives so the integrals are determined by using some
special methods sometimes numerical methods
1 the directivity is given by 0 = 42 = 42 2half power beamwidth is given by
50.6 50.6
fig(1.1.2) : the Rectangular
aperture antenna located in the x,yplane .
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1.2 Circular apertures antenna:
A widely used microwave antenna is the
circular aperture. One of the attractive
features of this configurationis its
simplicity in construction. In addition,
closed form expressions for the fields of
all the modes that can exist over the
aperture can be obtained.
To demonstrate the methods, the field
radiated by a circular aperture mounted on
an infinite ground plane will be formulated.
The electric field is given by:
r = 0 = j20 sin 1 sin sin
= j20 cos cos 1 sin sin
The directivity can be given by (the field distribution over the aperture is
constant):
D0=42 Aem= 42 Ap=42 (2) = ( 2 )2= ()2
fig(1.2.1) : the circular aperture
antenna located in the x,y plane .
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2MATLAB ProgramSimulation of antenna parameters by using MATLABsoftware is performed
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Part 1:
This Matlab code will execute 2D radiation pattern rectangular and
circular apertures antennas.
clc ;
antennatype=input('enter the antenna type:Rectangular(1) or
Circular(2)= ');
lamda=input('enter the value of wavelength= ');
theta=pi/100:2*pi;
B=2*pi /lamda; u=B.*(sin(theta)); v=B.*(sin(theta));
%1st choice: Rectangular Aperture
ifantennatype==1
a=input('Enter the large rectangular length a= ');
b=input('Enter the small rectangular length b= ');
E1=sinc((b.*v)./2); % Eplane phi=90
E2=sinc((a.*u)./2); %Hplane phi=0
figure(1)
subplot(1,2,1)
polar(theta,E1) , title('Eplane')
subplot(1,2,2)
polar(theta,E2), title('Hplane')
%2nd choice:Circular Aperture
elseifantennatype==2
a=input('Enter raduis of circular aperture= ');
f1=B*a;
f=f1.*(sin(theta));
E=(besselj(1,f))./f; %Eplane or Hplane
figure(2)
polar(theta,E)
end
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The output :
For rectangular with the parameters = = 5we have gottenthe following graph
at the case when = = we have gotten the following graph
fig(2.1.1) : rectangular aperture
radiation pattern in the E and H
plane
=
= 5
.
fig(2.1.2) : rectangular aperatureradiation pattern in the E and H
plane = = .
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Part 2:
3D radiation pattern of a rectangular aperture as a function of the
independent variables Vx ,Vy for aperture dimensions a = 8
and b = 4
.
clc;
b=4*lamda;
a=8*lamda;
B=2*pi /lamda; u=B.*(sin(theta)); v=B.*(sin(theta));
theta=0:0.01:pi/2;
phi=0:0.01:2*pi;
[theta,phi]=meshgrid(theta,phi);
vx=(a/lamda)*sin(theta).*cos(phi);
vy=(b/lamda)*sin(theta).*sin(phi);E1=sinc((b.*v)./2); % Eplane phi=90
E2=sinc((a.*u)./2); %Hplane phi=0
E=((1+cos(theta)./2).*abs(E1.*E2));
figure(4)
surfl(vx,vy,E);
shadinginterp;
colormap(gray);
fig(2.2.1) :
rectangular aperture
radiation pattern in3
D plane =8 = 3 .
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Part 3:
3D radiation pattern of a circular aperture as a function of the
independent variables Vx ,Vy for an aperture radius a = 3
.
clc;
a= 3;
theta=0:0.01:pi/2;
phi=0:0.01:2*pi;
[theta,phi]=meshgrid(theta,phi);
vx=(a/lamda)*sin(theta).*cos(phi);
vy=(a/lamda)*sin(theta).*sin(phi);
u=(a/lamda)*sin(theta);
E=ones(size(u));
i=find(u);
E(i)=abs(2*besselj(1,2*pi*u(i))./(2*pi*u(i)));
figure(4)
surfl(vx,vy,E);
shading interp;
colormap(gray);
fig(2.3.1) : circular
aperture radiation
pattern in3D plane
= 3
.
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3Explaining the results The concept of sinc and dirac impulse function
Simulation results
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3.2 simulation results
For a=100
we have the following result
So we have gotten a results that matches the theoretical concepts
fig(3.2.1) : circular
aperture radiation
pattern in3D plane = 100 all theradiation is
concentrated at the
origin and zero else
where.
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Conclusion
The radiation pattern of any antenna source it depend on the
antenna geometry and the length of the wavelength that is radiated by this
antenna, because the electromagnetic wave is always effected by the
obstacles under the concept of reflection, refraction, diffraction and
scattering phenomena. And this for main phenomena are related to the
concept of the wavelength and the dimension of the obstacles.
When the electromagnetic waves is radiated by an aperature
antenna a diffraction and scattering phenomena at the edges is occurred ,
this diffraction and scattering will be high when and in this casethe wave will spread everywhere and side lobes will be high in large
distance, at the case when the diffraction will not occur at theedges so radiation will keep traveling at straight line so it will remain
concentrated at the origin no spreading