broad array
Post on 03-Jun-2018
226 Views
Preview:
TRANSCRIPT
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 1/16
1
1. Broad Side Array 1: φ=0
N=2-20 and d=
In this section we are going to analyze the variation of number of elements (N)
while fixing the distance (d) between those elements.
MatLab Code:
lam=1/2;
N=input('Number of elements in array=');
d=lam/2;
theta=0:0.01:2*pi;
Bd=(2*pi/lam)*d*cos(theta);
num=sin(N*Bd/2);
den=sin(Bd/2);
F=abs(num./den);
polar(theta,F);
y=['N = ',num2str(N),'; Wavelength = 1/2'];
title(y);
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 2/16
2
0.5
1
1.5
2
30
210
60
240
90
270
120
300
150
330
180 0
N = 2; Wavelength = 1/2
2
4
6
8
30
210
60
240
90
270
120
300
150
330
180 0
N = 8; Wavelength = 1/2
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 3/16
3
5
10
15
30
210
60
240
90
270
120
300
150
330
180 0
N = 14; Wavelength = 1/2
5
10
15
20
30
210
60
240
90
270
120
300
150
330
180 0
N = 20; Wavelength = 1/2
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 4/16
4
Conclusion:
The above figures shows the radiation pattern at N=2, 8, 14 and20. From
the above figures we can conclude that as the number of elements N is
increased, decreases and consequently the Directivity increases.
In addition to that the numbers of side lobes are multiplying at the center
of the radiation pattern.
In order to avoid the appearance of grating side lobes in the radiation
pattern d should be ≤
.
The code below shows that we have modified d to be ≤
.
Matlab Code:
lam=1/2;
N=input('Number of elements in array=');
d=lam/4;
theta=0:0.01:2*pi;
Bd=(2*pi/lam)*d*cos(theta);
num=sin(N*Bd/2);
den=sin(Bd/2);
F=abs(num./den);
polar(theta,F);
y=['N = ',num2str(N),'; Wavelength = 1/4'];
title(y);
The simulation will be at N=8 and the figures below show the results.
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 5/16
5
The figure on the left shows that when we take d less than the wave length the sidelobes decrease, so as we decrease d the number of lobes decreases.
2
4
6
8
30
210
60
240
90
270
120
300
150
330
180 0
N = 8; Wavelength = 1/4
2
4
6
8
30
210
60
240
90
270
120
300
150
330
180 0
N = 8; Wavelength = 1/2
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 6/16
6
2. Broad Side Array 2:
In this section we have fixed the number of elements N and we vary
.
N=10 and
: 0.1-1.5
N=10;
d=input('Enter the distance between two elements=');
theta=0:0.01:2*pi;
Bd=(2*pi)*d*cos(theta);
num=sin(N*Bd/2);
den=N*sin(pi*d*cos(theta));
F=abs(num./den);
polar(theta,F);
y=['N = 10; Distance =',num2str(d)];
title(y);
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 7/16
7
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; Distance =0.6
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; Distance =0.1
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 8/16
8
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; Distance =1.5
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; Distance =1
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 9/16
9
Conclusion:
We can conclude from the above figures that as
increases, number of lobes will
increase and starts to radiate.
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 10/16
10
3. End-Fire Array 1: φ=βd
N=2-20 d=
In this section we are going to analyze the variation of the number of elements (N)while fixing the distance between those elements.
MatLab Code:
lam=1/2;
N=input('Number of elements in array=');
d=lam/4;
theta=0:0.01:2*pi;
f=(2*pi/lam)*d*cos(theta)-(2*pi/lam)*d;
num=sin(N*f/2);
den=sin(f/2);
F=abs(num./den);
polar(theta,F);
y=['N = ',num2str(N),'; d = lam/4'];
title(y);
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 11/16
11
2
4
6
8
30
210
60
240
90
270
120
300
150
330
180 0
N = 8; d = lam/4
0.5
1
1.5
2
30
210
60
240
90
270
120
300
150
330
180 0
N = 2; d = lam/4
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 12/16
12
5
10
15
20
30
210
60
240
90
270
120
300
150
330
180 0
N = 20; d = lam/4
5
10
15
30
210
60
240
90
270
120
300
150
330
180 0
N = 15; d = lam/4
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 13/16
13
Conclusion:
The above figures shows the radiation pattern at N=2, 8, 15 and20. From
the above figures we can conclude that as the number of elements N is
increased, decrease and we observe huge amount of side lobes at thecenter.
4. End-Fire Array 2:
In this section we have fixed the number of elements N and we have varied
.
N=10 and
: 0.1-1.5
N=10;
d=input('Enter the distance between two elements=');
theta=0:0.01:2*pi;
f=pi*d*(cos(theta)-1);
num=sin(N*f);
den=N*sin(f);
F=abs(num./den);
polar(theta,F);
y=['N = ',num2str(N),'; d/lam = ',num2str(d)];
title(y);
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 14/16
14
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; d/lam = 0.1
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; d/lam = 0.4
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 15/16
15
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; d/lam = 1
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; d/lam = 0.8
8/12/2019 Broad Array
http://slidepdf.com/reader/full/broad-array 16/16
16
Conclusion:
It’s clear that when we vary
: between 0.1 and 1.5 there’s unwanted
radiations resulted from the side lobes in unlike when we varied the
number of elements N.
0.2
0.4
0.6
0.8
1
30
210
60
240
90
270
120
300
150
330
180 0
N = 10; d/lam = 1.5
top related