t- shape antenna design for microwave band applications

Int. Journal of Electrical & Electronics Engg. Vol. 2, Spl. Issue 1 (2015) e-ISSN: 1694-2310 | p-ISSN: 1694-2426

NITTTR, Chandigarh EDIT -2015 86

T- Shape Antenna Design for Microwave Band Applications

Shalini Bhickta

Electronics & Communication Engineering Department AP Goyal Shimla University, Shimla, H.P

[email protected]

Abstract—It’s been studied fractal antennas shows promising future. There are numerous kinds of antenna, the thirst for excelling in this area is ever increasing. In this paper a Fractal based Antenna is designed to achieve reduced size and multiband. Fractal antenna is simulated using EM wave simulator like HFSS (High frequency structured simulator) and is designed and developed for multiple applications. The proposed antenna is experimentally realized using FR Epoxy substrate with dielectric constant 4.4 and thickness h= 1.56 mm with coaxial feeding. The patch has the dimensions of 2.5 cm 2.5 cm. An experimental result of this antenna shows multiband characteristics having resonances at frequencies such as 2.4 GHz , 6.8 GHz, 8 GHz, 10.8 GHz, 12.2 GHz,15.4 GHz with bandwidth of 230 MHz, 2 GHz, 600 MHz, 870 MHz and 2 GHz respectively. Further VSWR is also studied in this paper.

Index Terms—Fractal, Microstrip, Space filling, coaxial feed.

I. INTRODUCTION Antennas has till now proved as life to wireless communication systems. Future of such antenna is in there compact sizes, good antenna gain. There are many kinds of antenna that shows promising applications in various fields [1]. Micro strip patch antennas is one of them, they are simple, less expensive and low profile antennas. Several geometries have been explored with numerous characteristics to obtain desired results. Fractal nature of antenna sets this in different category of antenna. This paper shows the special type of antenna using Fractal technique, every iteration follows preceding iteration [2]. Fractal antenna can be simulated for much iteration until the desired result is achieved, they are multiband antenna. The concept of fractal antenna helps in designing multiband antennas [3]. . The two main properties of fractal antenna are self similarity in their structure i.e. a fragmented geometric shape that can be subdivided in parts, each of which is a reduced size copy of the whole [4]. Second is its space filling property which enable miniaturization of antenna for very this reason fractal antenna are very compact or multiband or wideband and have useful application in cellular telephone and microwave application [5]. Fractal structure is generated using Integrated Fractal system algorithm which uses a scaling factor [6] expressed as,

= (1)

Where, = scaling factor ratio

h = height of iterated antenna (T-shape) n = iteration number

II. ANTENNA DESIGN The proposed antenna is a multiband antenna based on the square fractal antenna. This structure is designed with space filling property of fractal antenna. The size of the antenna increases as the resonant frequency decreases. Therefore to operate antenna on same frequency fractal antennas are designed smaller in size. In this design the size of the antenna is 2.5 X 2.5 cm. The scaling factor for each of the iteration is taken as one – third (1/3) to maintain the perfect geometry symmetry. The first order geometry of T shape is of dimension (1. 35 cm X 1.35) cm, then two T shape (0.45 X 0.45 ) cm size are included on top of the previous T which forms the second order of geometry, third order geometry includes T-shape of (0.15 X 0.15) cm size. The conductor is copper clad, in terms of wavelength size of the proposed antenna is (where is the wavelength at lowest resonant frequency). Fig.1 shows the detailed structure of T-shaped fractal antenna after its third proposed iteration geometry.

The antenna is fed by coaxial line from a wave-port. The antenna is fabricated on FR4 Epoxy of relative permittivity 4.4 and the thickness of substrate is t=1.56 mm. Mathematically, resonating frequency of the antenna is calculated [7,8] using the equation (2)

=∈

(2)

c = speed of light, = resonant frequency ∈ = Effective permittivity and it is calculated using equation (3).

∈ = ∈ + ∈ ( )

(3)

III. RESULTS AND DISCUSSION

A. Simulation Results The proposed antenna is simulated on High Frequency Structured Simulator (HFSS), characteristics of proposed antenna have been analyzed on several parameters like


87 NITTTR, Chandigarh EDIT-2015

Fig.1 Geometry of proposed antenna

VSWR, return loss, total gain and radiation pattern. Fig.2 gives the VSWR (Voltage standing wave ratio) for the

proposed antenna which shows promising results of VSWR < 2.

Fig.3 shows the return loss of the proposed antenna i.e. -14.53 dB, -21.31 dB, -24.14 dB, -16.69 dB, -21.83 dB, -16.7 dB and -19.836 dB respectively with bandwidth of 230 MHz, 2 GHz, 600 MHz, 870 MHz and 2 GHz at the resonant frequencies. The figure depicts that, this antenna is multiband

Fig.2. VSWR (Voltage standing wave ratio) of antenna

applied at frequencies 2.4 GHz, 6.8 GHz, 8 GHz, 10.8 GHz,.2 GHz, and 15.4 GHz since in these frequencies the simulated coaxial fed return loss S11 < −10 dB.

0.00 2.50 5.00 7.50 10.00 12.50 15.00 17.50 20.00Freq [GHz]

0.00

2.50

5.00

7.50

10.00

12.50

15.00

17.50

20.00

22.50

25.00

27.50

30.00

dB(V

SWR

(1))

HFSSDesign1XY Plot 2 ANSOFT

m1

m2 m3m4

m5m6

Curve InfodB(VSWR(1))

Setup1 : SweepName X Ym1 2.4000 3.2894m2 6.8000 1.4967m3 7.5000 2.1598m4 8.1000 1.1745m5 10.8000 2.5600m6 12.1000 1.3493


NITTTR, Chandigarh EDIT -2015 88

Fig.3. Return loss of the proposed antenna design

Fig.4 shows the total field gain of the antenna. The result at 2.4 GHz, 8GHz & 15.4 GHz resonant frequencies gives better total gain as compared with other resonant frequencies at Phi = 0 degree & theta all. VSWR of the geometry at different iterations is studied and shown as graphical representation of VSWR w. r. t the resonant frequencies of the antenna in Fig.5. Here, the VSWR of the final iterated geometry is better as compared to the VSWR of first & second iteration of the T-shape antenna.

Fig.4 Total gain of the antenna

B. Comparison of Simulated VSWR vs. Frequency

Fig.5. VSWR vs. FREQUENCY

The azimuth and elevation radiation patterns are simulated in all the resonant frequencies. Fig. 6 & 7 shows the simulated Elevation & azimuth radiation pattern of the antenna. The simulation has been carried out at resonances as observed in the S11 measurement.

0.00 2.50 5.00 7.50 10.00 12.50 15.00 17.50 20.00Freq [GHz]

-25.00

-20.00

-15.00

-10.00

-5.00

0.00dB

(S(1

,1))


m3

m4

m5

m1

m6

m2

Curve InfodB(S(1,1))

Setup1 : Sw eep

Name X Ym1 2.4000 -14.5576m2 6.8000 -21.3158m3 8.0000 -24.1466m4 10.8000 -16.6947m5 12.2000 -21.8308m6 15.4000 -16.7081

-100.00 -75.00 -50.00 -25.00 0.00 25.00 50.00 75.00 100.00Theta [deg]

-10.00

-5.00

0.00

5.00

10.00

15.00

dB(G

ainT

otal

)


Curve InfodB(GainTotal)

Setup1 : SweepFreq='2.4GHz' Phi='0deg'

dB(GainTotal)Setup1 : SweepFreq='8GHz' Phi='0deg'

dB(GainTotal)Setup1 : SweepFreq='15.4GHz' Phi='0deg'

0

1

2

3

4

5

6

7

2.4 6.8 8 10.8 12.2 15.4

VSW

RVSWR v.s FREQUENCY

VSWR of entire GeometryVSWR of first iterationVSWR of second iteration

FREQUENCY


89 NITTTR, Chandigarh EDIT-2015

Fig.6 Elevation pattern of the proposed antenna. Fig.7 Azimuth pattern of the proposed antenna.

IV. CONCLUSION The proposed T-shaped fractal microstrip patch antenna is simulated over High Frequency Structure Simulator (HFSS) software as a simulation tool. Various characteristics like total field gain, return loss, radiation pattern and VSWR has been obtained from the simulation results. The antenna design can work in different microwave bands according to the results. This paper also depicts as we increase the number of iterations the gain and VSWR at different resonant frequencies gets better. The proposed antenna design finds applications in X-band, Radars, Medical, Satellite & WLAN communications.

REFERENCES [1] Amit Kumar Tripathi & Dr.B.K.Singh,“A CPW Fed X- Band

Antenna for Satellite & Radar Applications”, IEEE conference 2013.

[2] Javad Pourahmadazar, Changiz Ghobadi, and Javad Nourinia, “Novel Modified Pythagorean Tree Fractal Monopole Antennas for UWB Applications”,IEEE Antennas and Wireless Propagation Letters, Vol. 10, 2011.

[3] Neetu, Savina Banasl, R K Bansal, “Design and Analysis of Fractal Antennas based on Koch and Sierpinski Fractal Geometries”, International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering Vol. 2, Issue 6, June 2013.

[4} Khidre , Ahmed. Lee, Kai Fang., Yang, Fan., and Eisherbeni, Ate., “Wideband Circularly Polarized E-shaped Patch Antenna for Wireless Applications,” IEEE Antennas and Propagation Magazine , Vol. 52 No.5., 2010.

[5] Jaon Gemio, Josep Parron Granados, and Jordi Soler Castany, “Dual Band Antenna with Fractal Based Ground Plane for WLAN Application,” IEEE Antennas and Wireless Propagation Letters, Vol. 8, pp. 748-751, 2009.

[6] S.Sankaralingam, Bhaskar Gupta,“Determination of Dielectric Constant of Fabric Materials and Their Use as Substrates for Design and Development of Antennas for Wearable Applications”, IEEE Transactions on Instrumentation and Measurement, vol. 59, no. 12, December 2010.

[7] Kumar,S.,Gangwar,D.,Yadava,R.L., “Miniaturized inverted multiband stacked triangular fractal patch antenna for wireless communication”, Signal Processing and Integrated Networks (SPIN), International Conference , p.p, 667 – 670, feb 2014.

[8] J. Guterman, A. A. Moreira and C. Peixeiro, “Dual-Band Miniturized Microstrip Fractal Antenna for a Small GSM1800 + UMTS Mobile Handset,” IEEE Melecon 2004, Dubrovnik, Crotia, pp. 499-501, May 12-15, 2004.

[9] C.A. Balanis, “Antenna Theory analysis and design”, Microstrip Antennas, Chapter 14, p.p. 720-784.

[10] Sujeet Kumar Yadav1, Kirti Vyas2, Sudarshan Kumar, “A Pythagoras Tree Shape Fractal Antenna for Multiband Applications”, International Journal of Emerging Technology and Advanced Engineering, Volume 3, Issue 12, December 2013.

[11] A. Aggarwal and M.V. Kartikeyan, “Pythagoras Tree: A Fractal Patch Antenna For Multi-frequency and Ultra-Wide Bandwidth operations”, PIER, Vol. 16, pp 25-35, 2010.

t- shape antenna design for microwave band applications

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