Endfire Antennas

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National Conference On Electrical Sciences -2012 (NCES-12) ISBN: 978-93-81583-72-2

Department Of EEE, Annamacharya Institute Of Technology & Sciences, Rajampet 26

ANALYSIS OF RADIATION PATTERNS FOR BROAD SIDE AND END FIRE ARRAY DUE TO

SEPARATION OF ELEMENTS AND NUMBER OF ELEMENTS

Shashi Kumar. D

Asst. Professor, Dept. Of ECE, Christ University, Bangalore, India.

Email: [email protected]

ABSTRACT:

In the present day antenna systems, the two types

of Antenna arrays are majorly used: Broadside

array and End fire array. They are used to radiate

their own beam patterns. The antenna arrays with

different arrangements: The Spacing of the

elements and the Number of elements may produce

the diverse radiation properties. The overall

radiation pattern of an array is determined byarray factor combined with the radiation pattern of

the antenna element. The overall radiation pattern

results in certain directivity and different lobes

with different number of elements and different

spacing between them. Thus in this paper analysis

is made on the effect of number of elements and the

spacing between the elements on broadside array

and end fire array. And the comparative

conclusions are drawn [3, 4]

KEYWORDS:

Antenna array; broadside array; End fire array; Arrayfactor; Number of elements; Spacing between the

elements; Radiation patterns.

INTRODUCTION:

Antennas have become ubiquitous devices and occupy

a salient position in wireless systems. Radio and TV as

well as satellite and new generation mobile

communications have experienced the largest growth

among industry systems.

The global wireless market continues to grow at

breakneck speed and the strongest economic and

social impact nowadays comes from cellular

telephony, personal communications and satellitenavigation systems. All of the above systems have

served as motivation for engineers to incorporate

elegant antennas into handy and portable systems. A

device able to receive or transmit electromagnetic

energy is called an antenna. [1, 2]

Antenna array:

An antenna array is a configuration of multiple

antennas (elements) arranged to achieve a given

radiation pattern. A single-element antenna is usually

not enough to achieve technical needs. That happens

because its performance is limited. The set of discrete

elements, which constitute an antenna array, offers the

solution to the transmission and/or reception ofelectromagnetic energy. [1]The geometry and the type

of elements characterize an antenna array. Antenna

array factor quantifies the effect of combining

radiating elements in an array without the element

specific radiation pattern taken into account. The

overall radiation pattern of an array is determined by

this array factor combined with the radiation pattern of

the antenna element. The overall radiation pattern

results in a certain directivity and thus gain linked

through the efficiency with the directivity. Directivity

and gain are equal if the efficiency is 100% [2].

Classification:The phasing of the uniform linear array elements may

be chosen such that the main lobe of the array pattern

lies along the array axis (end-fire array) or normal to

the array axis (broadside array).

Broad side array:

Broad side array is the arrangement of identical

antennas, which are placed along the axis

perpendicular to the direction of maximum radiation.

The identical antennas are equally spaced along the

line of axis and all the elements are fed with equal

magnitude of current with the same phase. This results

in array pattern known as broad side array. It is

evident that broad side array is bidirectional wheremaximum radiation is obtained in the direction of axis

perpendicular to the array axis. By placing an identical

array at a distance of /4 behind the array,

bidirectional array can be converted to unidirectional


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array and by lead current in phase by .

End Fire Array:

An End fire array looks similar to broad side array

except that the individual elements are fed with thecurrent that is equal in magnitude but opposite in

phase. In other words, the individual elements are

excited in such a way that a progressive phase

difference between adjacent elements becomes equal

to the spacing between the antennas (elements).

The arranging of identical antennas along a line

drawn perpendicular to their respective axis so that the

principle direction of radiation coincides with the

direction of the axis of array is known as End fire

array. The radiation is maximum in the direction along

the axis of the array i.e., 0 degree (or) 180 degree.

If two equal radiators are operated in phase quadrature

at a distance of /4 apart, an end fire couplet is said to

be formed.

In this paper comparison of radiation patterns withrespect to number of elements and the distance

between the elements is done by using MATLAB

software.

FORMULAE USED

d*Cos(Phase difference between the adjacent

elements

d=Distance between the elements

Array factor for N element antenna array is

defined as

=

(

)

(

)

[1, 2, 3, 4]


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CONSTANT.

BROAD SIDE ARRAY END FIRE ARRAY

0.2

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N=4, d=0.25

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N=4, d=0.5

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N=4, d=0.75

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N=4, d=1

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N=4,d=0.5

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N=4,d=0.75

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N=4,d=1


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RESULT ANALYSIS:

The radiation patterns are developed for differentnumber of elements and the spacing between them, the

broadside and end fire arrays consists of main lobe,

side lobe and nulls which are plotted using MATLAB

software.

First let us analyze the condition for the constantnumber of elements and varying the spacing between

them:

As the spacing between the elements is increasing, the

directivity of the antenna reduces and the number of

side lobes increases that is the size of main lobe isreducing as we increase the spacing between them.

As the spacing between the elements is decreasing, the

directivity of main lobe increases.

At N=4 and d=1 the patterns of end fire array becomessame. Thus we can conclude that, the area of coverage

of antenna array is inversely proportional to thespacing between them.

Analyze the effect of number of elements on the

radiation patterns:

In case of end fire array, direction of main lobe

remain unchanged, as the spacing remain unchanged

throughout the results that are obtained But the minorlobes increased and main lobe little bit become narrow

as the number of elements increases. In case ofbroadside array, it is clearly shown in results that the

directivity is more compared to the directivity of end

fire array. As the main lobe in broad side array is very

much narrow, and also pattern is symmetrical, but thegrating lobes appears with increase in number of

elements. End fire array is unidirectional as spacing is

constant here, only the number of elements are varied,

it may be bidirectional if the spacing is increased

The broadside array is bidirectional as it is shown in

results, and produces more symmetrical pattern andcan be used for long distance communication where

directivity needed to be strong. End fire array provide

directional radiations and stable unidirectional

radiation pattern. Thus to get more directivity size ofarray has to be more. It can be used in satellite dish

antennas, where a very high directivity is needed,

because they are to receive signals from a fixeddirection.[4]

CONCLUSION

The Effect of number of elements and the spacingbetween them on the radiation pattern of broadside

array and end fire array are analyzed and compared inpresent paper. In general the directivity of end fire

array is more as compared to broad side array, but the

end fire array produces stable unidirectional

radiations. And broadside array gives more symmetric

pattern as the pattern is bidirectional and can be used

for applications where more area coverage is needed.The end fire array can be used to construct directional

antennas and can be used in satellite dish antenna to

receive signal from fixed direction.

REFERENCES:

1: Balanis, C.A., Antenna Theory: Analysis andDesign, John Wiley & Sons, New York, N.Y., 1982

2: Krauss.J D Radio astronomy antennas Tata

McGraw hill, 1996

3: Amanpreet kaur, Amandeep Singh, Comparison

between the radiation pattern of uniform circular

array and uniform planar array. International Journal

of Computer Networks and Wireless Communications

(IJCNWC), ISSN: 2250-3501, Vol.2, No.2, April 2012

4: Amanpreet kaur, zonunmawii, Shakti raj chopra,

Comparison between the radiation pattern of

broadside array and end fire array. Nationalconference on challenges in emerging computer

technologies (CECT2012), vol.4, pp 135-137

0.2

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N=16, d=0.25

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N=16,d=0.25

Endfire Antennas

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