# Tapering of Arrays

Topics: Array, Fundamental physics concepts, Ratio Pages: 2 (410 words) Published: August 21, 2012
Tapering of Arrays
By Jaydeep Trivedi (09BEC096)
And
Kedar Trivedi (09BEC097)
1) Introduction:
The code shown below is used to show the radiation pattern due to variable no of point sources, variable distance of the point of interest and variable wavelength. This code also determines the locations of all the nulls due to different input fed to the sources. Mostly we will be discussing three different feeding methods: uniform feeding, edge feeding and binomial feeding. 1.1) uniform pattern:

In uniform pattern all the array elements are active and are fed equal input. This type of feeding results in an SLL of -12dB and HPBW of 230. The radiation pattern for a normalized field due to 5 sources of 600MHz with a distance lambda/2 is shown below: 1.2) Edge pattern:

In edge pattern only two array elements are active and are fed equal input while the rest are all passive. This type of feeding results in an SLL of 0dB (which means that all the lobes are of equal amplitude) and HPBW of 130. The radiation pattern for a normalized field due to 5 sources of 600MHz with a distance lambda/2 is shown below: 1.3) Binomial pattern:

In uniform pattern all the array elements are active and are fed unequal input and are fed according to the ratio in Pascal’s Triangle. This type of feeding results in an SLL of almost 0dB and HPBW of 310. The radiation pattern for a normalized field due to 5 sources of 600MHz with a distance lambda/2 is shown below:

2) Matlab Code:
n=input('enter no of sources');
eo=input('enter the electric field value');
mm=input('enter distance in terms of wavelength');
f=input('enter frequency');
c=3*10^8;
lambda=c/f;
d=lambda*mm;
beta=2*pi/lambda; %calculating beta

for o= 1:1:360
d2r(o)=o*pi/180; %converting degree to rad for plotting purpose phi=beta*d*cos(d2r(o)); %calculating phi(phase angle)
e(o)=eo*(sin(n*phi/2)/sin(phi/2)); %uniform pattern
e2(o)=eo*(cos(phi/2)^(n-1)); %binomial pattern
e3(o)=eo*(2*cos((n-1)*phi/2));...

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