CIRCULARLY POLARIZED TRIANGULAR RING SLOT ANTENNA WITH DGS FOR HARMONIC SUPPRESSION · 2016-09-09 · CIRCULARLY POLARIZED TRIANGULAR RING SLOT ANTENNA WITH DGS FOR HARMONIC SUPPRESSION

CIRCULARLY POLARIZED TRIANGULAR RING SLOT

ANTENNA WITH DGS FOR HARMONIC SUPPRESSION

Ch. Hanusha

M.Tech Student, Dept. of ECE

Acharya Nagarjuna University

Guntur, India.

Email:[email protected]

K. Lakshmi Bhavani

Assistant Professor, Dept. of ECE

Acharya Nagarjuna University

Guntur, India.

Email:[email protected]

Abstract:

In this paper a triangular ring slot antenna is

proposed which is designed to operate at 5.5GHz.

Apart from this fundamental mode, additional

harmonics are produced. These harmonics are

suppressed by integrating an inverted U-shaped slot

into the antenna. This defected ground structure is

used to achieve harmonic suppression at 11GHz and

15GHz. Further a tilted slot is embedded in the ring

slot antenna to produce circular polarization

Keywords: Defected ground structure (DGS),

Circular polarization, and Triangular ring slot

antenna.

1. Introduction:

The radio frequency communication device

is a combination of active and passive elements. The

power amplifier and low noise amplifier constitute

the active elements while antenna and filter constitute

the passive elements [1] [2]. The size of the RF

circuit can be minimized by integrating the antenna

with the power amplifier. This active integrated

antenna design poses the problem of reducing the

power amplifier efficiency due to electromagnetic

interference caused by higher order modes excited by

the antenna [3].

To avoid this problem, the higher order

modes or Harmonics which are repeated at multiples

of fundamental frequency are to be suppressed [4].

Thus it is ideal to use a low pass filter along with the

antenna. Various methods to suppress the unwanted

modes include loading of additional tuning stubs and

multiple shorting pins into a patch antenna. These

methods were proved to be inefficient in terms of

suppressing band width. In order to obtain wide

suppressing band width, defected ground structure

can be used [5] [6]. This technique involves

integration of various types of slots with the patch

Antenna. In this paper an inverted U-shaped slot is

loaded on the triangular ring slot antenna [7] [8]. The

satellite communications use circular polarization

since the ionosphere tends to change the polarization

of the transmitted wave

. This is a problem, if linear polarization is

used. In circular polarization the electric field is

passing wave does not change strength but only

changes direction in a rotary manner. The use of

circular polarization at each end of link reduces

fading and flutter.

2.Antenna design:

The satellite communication system uses the

C-band with frequency range from 4GHz-8GHz.

Hence the antenna designed must be able to operate

in this frequency range.

The operating frequency selected for the

design is 5.5GHz. And the dielectric material is FR4

which has a dielectric constant of 4.4.

The side of the inner triangle is t1= 10mm and

Side of the outer triangle is t2=14mm is calculated by

the formulae

Circle radius (a) = side of the triangle (t)/sqrt (3),

a1= inner circle radius and

a2 = outer circle radius.

0F =r

r

aa

c

ξ

ξ 1.

)21(

+

+∏.

Where 0F = operating frequency,

rξ = relative permittivity of the substrate,

c= velocity of light,

International Journal of Scientific & Engineering Research, Volume 6, Issue 5, May-2015 ISSN 2229-5518

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Fig: 1. C-Band antenna without defected ground

structure

The harmonics obtained for this antenna are

suppressed by using defected ground structure

(DGS). The antenna with defected ground structure is

shown below.

Fig: 2. proposed antenna with defected ground

structure

3.Circularly polarized ring slot antenna:

To achieve circular polarization for the

triangular ring slot antenna mentioned above, a tilted

slot is cut as shown in below figure.

Fig: 3. proposed circularly polarized antenna

4.Simulation:

The simulation of patch antenna is done

using HFSS (high frequency structural simulator)

version 14.0. It uses finite element method (FEM) for

solving electromagnetic structures and designs of

antennas, RF electronic circuit elements such as

filters and transmission lines.

5.Results and analysis:

For this C-band triangular ring slot antenna

the Return loss of -23.3db is obtained at 5.5GHz. The

harmonics are obtained at 11GHz, 15GHz.

2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00Freq [GHz]

-37.50

-25.00

-12.50

0.00

dB

(S(1

,1))

HFSSDesign2XY Plot 1 ANSOFT

m1

m2

m3

Curve Info

dB(S(1,1))Setup1 : Sw eep

Name X Y

m1 5.9000 -23.3702

m2 11.4000 -37.0947

m3 15.1000 -10.9662

Fig: 4. Return loss without DGS

The harmonics 12GHz and 15GHz are

suppressed by using defected ground structure. The

return loss curve for defected ground structure

antenna is shown below. The return losses at 12GHz


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and 15GHz are reduced to 7.6db and 8.21 db

respectively.

2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00Freq [GHz]

-22.50

-20.00

-17.50

-15.00

-12.50

-10.00

-7.50

-5.00

-2.50

0.00

dB

(S(1

,1))


m1

m2m3

Curve Info

dB(S(1,1))Setup1 : Sw eep

Name X Y

m1 5.4000 -22.1943

m2 12.0000 -7.6143

m3 15.5000 -8.2146

Fig: 5. return loss of DGS antenna

The polarization is observed to be linear

from the axial ratio curve shown below.

0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00Theta [deg]

10.00

20.00

30.00

40.00

50.00

60.00

70.00

dB

(Ax

ialR

ati

oV

alu

e)


m1

Curve Info

dB(AxialRatioValue)Setup1 : LastAdaptiveFreq='5.5GHz' Phi='0deg'


Name X Y

m1 0.0000 56.4202

Fig: 6. axial ratio curve of DGS antenna

3D-polar plot:

The total gain of 3.74dB is observed from

3D-polar plot is shown in below figure.

Fig: 7. 3D-polarplot

Circularly polarized ring slot antenna:

The tilted slot which is cut on the triangular

ring slot antenna gives circular polarization. The

axial ratio measured is found to be 2.69db.

0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00Theta [deg]

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

dB

(Ax

ialR

ati

oV

alu

e)


m1

Curve Info



Name X Y

m1 0.0000 2.6915

Fig: 8. axial ratio of circularly polarized antenna

3D-polar plot and radiation pattern:

The total gain of 3.20 dB is observed from

3D-polar plot as shown in figure.9. The simulated

radiation pattern of the antenna at 5.5GHz is shown

in figure.10.


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Fig: 9. 3D-polar plot

-5.60

-3.20

-0.80

1.60

90

60

30

0

-30

-60

-90

-120

-150

-180

150

120

Radiation Pattern 1

Fig: 10. Radiation pattern

Conclusion:

A U-shaped defected ground structure is

designed and loaded onto the triangular ring slot

antenna for harmonic suppression. The higher order

modes at 11GHz and 15GHz are effectively

suppressed. Along with this, circular polarization is

achieved by the use of a tilted slot on the triangular

patch. The Axial ratio thus observed is 2.69dB.

References:

[1] K. Chang, R. York, P. Hall, and T. Itoh, “Active

integrated antennas,”IEEE Trans. Microw. Theory

Tech., vol. 50, no. 3, pp. 937–944, Mar.2002.

[2] D. Segovia-Vargas, D. Castro-Galán, L. E.

Garc´ıa-Muñoz, and V.González-Posadas,

“Broadband active receiving patch with resistive

equalization,” IEEE Trans. Microw. Theory. Tech.,

vol. 56, no. 1, pp.56–64, Jan. 2008.

[3] V. Radisic, Y. Qian, and T. Itoh, “Novel

architectures for high-efficiency amplifiers for

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Tech., vol. 46, no. 11, pp. 1901–1909, Nov. 1998.

[4] V. Radisic, S. T. Chew, Y. Qian, and T. Itoh,

“High efficiency power amplifier integrated with

antenna,” IEEE Microw. Guided Wave Let. vol. 7, no.

2, pp. 39–41, Feb. 1997.

[5] Y. J. Sung, M. Kim, and Y. S. Kim, “Harmonics

reduction with defected ground structure for a micro

strip patch antenna,” IEEE Antennas Wireless

Propag. Let. vol. 2, pp. 111–113, 2003.

[6] S. Biswas, D. Guha, and C. Kumar, “Control of

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[7] D. H. Choi, Y. J. Cho, and S. O. Park, “A

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1987, Oct. 2006.

[8] J. S. Park, J. H. Kim, J. H. Lee, S.H. Kim, and S.

H. Myung, “A novel equivalent circuit modeling

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[9] Bahi I J & Bharta P, micro strip antenna(artech

house, Massachusetts, USA),1980.

[10] lu jui-han & wong kin lu, single- feed circularly

polarized equilateral- triangular micro strip antenna

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CIRCULARLY POLARIZED TRIANGULAR RING SLOT ANTENNA WITH DGS FOR HARMONIC SUPPRESSION · 2016-09-09 · CIRCULARLY POLARIZED TRIANGULAR RING SLOT ANTENNA WITH DGS FOR HARMONIC SUPPRESSION