Journal of Computing::Gain Improvement of Micro Strip ...€¦ · Patch antenna, Gain, Dual patch, Ku-band, Radiation pattern, GEMS Software. 1. INTRODUCTION . A MICROSTRIP ANTENNA

VOL. 3, NO.12 Dec, 2012 ISSN 2079-8407 Journal of Emerging Trends in Computing and Information Sciences

©2009-2012 CIS Journal. All rights reserved.

http://www.cisjournal.org

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Gain Improvement of Micro Strip Antenna Using Dual Patch Array Micro Strip Antenna

1Md. MahabubAlam, 2RifatAhmmedAoni,3Md. Toufikul Islam 1, 2, 3Department of Electronics & Telecommunication Engineering, Rajshahi University of engineering and Technology,

Rajshahi-6204, Bangladesh 1 [email protected],[email protected],3

This paper represents a dual array patch micro strip antenna which operates in KU-band. The proposed dual array patch micro strip antenna was light weighted, flexible & slim and designed on two-layer, one

[email protected]

ABSTRACT

PTFE/Teflon substrate and another ground plane with two patches having an area of 8 mm×6.3 mm each. In this study, a dual array designed technique for enhancing gain that improved the performance of a conventional micro strippatch antenna. The result showed satisfactory performance with maximum achievable gain of about 10 dB. The objective of this study was to obtain the enhancement in gain (dB) for KU-band over the frequency band (10.9GHz–17.25GHz). Furthermore, this antenna provided a stable radiation pattern across the operating bandwidth. Keywords: Patch antenna, Gain, Dual patch, Ku-band, Radiation pattern, GEMS Software.

1. INTRODUCTION A MICROSTRIP ANTENNA (MSA) [1] in its simplest form consists of a radiating patch on one side of a dielectric substrate and a ground plane on the other side. Micro strip antennas are popular for their attractive features such as low profile, low weight, low cost, ease of fabrication and integration with RF devices. The major disadvantages of Micro strip antennas are lower gain and very narrow bandwidth [2, 3].The gain can be increased by using the micro strip antenna array structure but this again increases the size. Hence the gain of micro strip antenna (MSA) is increased by slightly increasing the dimensions of patch antenna and multilayer structure with covered dielectric [4]. Antenna arrays are used in order to achieve higher gain. The larger number of antenna elements, the better gain of antenna array is achieved. Antenna arrays are more demanding for EM simulation than single element antennas due to their electrical size. The objective of this paper is to study the dual array patch antenna examined in [5] and improve its bandwidth and gain. However, a dual array patch antenna can be used to receive the KU-band signals [6]. Ku band is primarily used for satellite communications, most notably for fixed and broadcast services. A direct broadcast satellite is a communications satellite that transmits to small DBS satellite dishes (usually 18 to 24 inches or 45 to 60 cm in diameter). Direct broadcast satellites generally operate in the upper portion of the microwave Ku . The proposed antenna has 2 elements arranged in a rectangular grid form and operated in TM11 mode [7]. For the numerical analysis we consider the substrate permittivity of the antenna is εr =2.08(

band

PTFE/Teflon) with substrate thickness .381 mm and feed by a 50 Ω micro strip line. The paper is divided as follow: Section 2 discusses the antenna design and structure;

Section 3 presents design issue of dual patch MSA,Section 4 explains the Antenna design procedure; Section 5 explains Simulation result of the antenna; Section 6 discusses conclusions; Section 7 future works of the paper. 2. ANTENNA DESIGN & STRUCTURE In this paper several parameters have been investigated using GEMS (General Electromagnetic Solver) version 7. The design specifications for the proposed antenna are:

Thickness of the substrate (h): 0.381 mm (0.02λ).

Patch size: 8 mm (0.4λ ) by 6.3 mm (0.315 λ)

Substrate dielectric (εr ): 2.08 Antenna resonating frequency: 14.74 GHz Antenna gain: 10 (dB) Antenna bandwidth: 48 MHz (-8dB) Antenna Efficiency: 88 % Input Impedance: 50 Ω

The antenna is fed by 50Ω micro strip line, through a quarter-wavelength transformer for impedance matching. The main advantage of using transmission line feeding is very easy to fabricate and simple to match by controlling the inset position and relatively simple to model.

mailto:1%[email protected]

mailto:[email protected]

http://en.wikipedia.org/wiki/PTFE

http://en.wikipedia.org/wiki/Satellite_communication

http://en.wikipedia.org/wiki/Direct_broadcast_satellite

http://en.wikipedia.org/wiki/Satellite_dish

http://en.wikipedia.org/wiki/Ku_band

http://en.wikipedia.org/wiki/PTFE

VOL. 3, NO. 12, Dec 2012 ISSN 2079-8407 Journal of Emerging Trends in Computing and Information Sciences



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(a)

(b)

Fig1:Dual patch antenna array a)Structure b)Antenna Dimension.

3. THE DESIGN ISSUE OF DUAL PATCH MICROSTRIP ARRAY ANTENNA 3.1 Rectangular Patch Antenna Analysis For the given resonance frequency f0 , the effective length is given by [10] as, Leff = c

2f0εeff

For rectangular micro strip antenna, the resonance frequency for anyTMmn mode is given by james and hall [11] as:

f0 = c2εeff

[mL

2+ n

W

2]1/2

For efficient radiation, the width W is given by Bahl and Bhartia [12] is W= c

2f0εr +1

2

The expression for εeff is given by Balanis [13] as: εeff = εr + 1

2+ εr− 1

2[1 + 12 h

w]1/2

3.2 Analysis of Antenna Arrays In this study, a dual array patch antenna is examined similar to the one in [9].Although a single element patch antenna may provide the desired antenna characteristics, combinations of many micro strip antennas into an array enable the designer to fabricate micro strip antennas with high gain, beam shaping and beam steering capabilities. Control over such characteristics is only possible with the formation of antenna arrays. Arrays of antennas usually consist of a repetition of radiating elements in a regular fashion. The elements may be identical or different and the structure may be configured as a linear, planar or volume array. Each element is also located at a specific distance from the other. The spacing between each element causes the fields from each element add or subtract in the far field to produce the desired radiation pattern. A practical reason supporting the feasibility of micro strip antenna arrays is the fact that conventional printed circuit etching processes are accurate, repeatable and relatively low in cost. In the simple array theory, each radiator is first treated as a point isotropic source. The contributions from each point is derived in the far field and expressed as an array factor (AF). The array factor may be said to be the ‘standard’ pattern and depends only of the geometry of the array and the phase between each element. Each point is then replaced by the actual radiator and the far field radiation pattern is then determined by pattern multiplying the array factor with the pattern of the radiator. Mutual coupling is ignored in the process since the radiators are treated separately also their influence on each other are not considered. The simple array theory also does not account for the presence of other objects such as feed lines or obstructions. 3.3 Input Impedance Matching Impedance matching is critical in micro strip antennas since the bandwidth of the antenna depends upon it. Besides this, a poor match results in lower efficiency also. Line fed rectangular patches may be fed from the radiating or the non-radiating edge. To find an impedance match along the non-radiating edge we may use the Transmission Line Model. The input impedance along the non-radiating edge is lowest at the center since two equally high impedances at the two ends are transformed into a low value at the center and connected in parallel. Matching along the edge is also symmetrical about the mid-point of the length. The input impedance at any location z along the edge may be determined by Yin (z) =2G× [cos2(βz)+G2+B2

Y02 sin2(βz) − B

Y0sin(βz)]

The input impedance at the radiating edge is given by Yin =G+jB+Y0 × [ G+j(B+Y0tan βL)

Y0+j(G+jB )tan(βL)]




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4. ANTENNA DESIGN PROCEDURE

Fig 2:Dual patch array MSA using GEMS This section describes the approach of designing a dual patch array antenna to adapt the structure to the desired interest operating frequency. The proposed antenna consists of a ground plane, a printed patch and a micro strip feeding line. The most important parameters that affect the antenna performance, such as impedance bandwidth, gain and efficiency are described in this section.

Fig 3: Return loss of dual patch array MSA As shown in Fig.3, the simulation indicates a response at 14.74GHz with return loss = -26.36dB.A negative value of return loss shows that this antenna had not many losses while transmitting the signals.

Smith chart

Fig 4:Smith chart display of the dual patch MSA

Fig 5: The antenna’s input impedance 5. SIMULATION RESULT The radiation patterns at the center frequency 14.74GHz, forKu band is plotted as shown below-




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Fig 6:Simulated gain in 2D view of dual patch array MSA

Fig 7: Axial ratio of dual patch array MSA at 14.7 GHz

Fig 9: H-plane at 4.74 GHz

Fig 10:Elevation Pattern of E Right, E left, E theta, E

Phi at phi=0 (deg)

Fig 8: E-plane at 4.74 GHz




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Fig 11:Elevation Pattern of E Right, E left,E theta, E Phiat

phi=90 (deg)

Fig 12: Azimuth Pattern of E Right, E left, E theta,E Phi at theta=90(deg)

Fig 13: Gain at 14.74 GHz in 3D view with main design

Fig 14: Radiation efficiency of dual patch array MSA

Fig 15:Power of dual patch array MSA




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6. CONCLUSION Dual patch array antenna has been designed for high gain. This dual patch array antenna is investigated and successfully simulated in this paper; the simulated return loss, bandwidth and radiation pattern showed well performance for the single band at 4.74GHz. The results of the array geometry are compared with those of single element of equilateral triangular patch micro strip antenna. It is found that there is a significant change in the radiation characteristics of array geometry. In the case of EM-mode, the shape of the field pattern has been modified to a great extent. It is also observed that the radiation patterns of a single element antenna contain only one major lobe of considerably wide beam-width, while the array geometry produces a directive beam with a narrow beam-width. Using this dual patch array MSA 10 dB gain and 48 MHz bandwidth were obtained which is sufficient for data processing for the system. It can be concluded from the above results that, designing a proper feed network and impedance matching are very important parameters in micro strip patch antenna design.

Also choosing a proper position for terminating the feed line affects the overall performance of the antenna. 7. FUTURE WORK The future work of this Project is to extend the design to 1x8 Antenna Array as well as 16x16 Antenna Array and improve the bandwidth of dual patch array micro stripantenna. Different types of feed methods affect the performance of an antenna. In this paper, micro strip line feed was chosen. In the future study we would like to investigate that, how other types of feed network affect the performance of micro strip antennas as compared to the micro strip line feed. The performance of bandwidth will be increased by using Proximity Coupled Feed. ACKNOWLEDGMENTS The authors would like to thank the teachers of the Department of Electronics and Telecommunication Engineering, RUET for providing us with best facilities and suggestions, All gratitude to the omnipotent “ALLAH” who guides us to bring forth to light this paper. All thanks goes especially to our parents for their prayer and inspiration, which has helped us in becoming what we are today. REFERENCES [1] W.L. Stutzman and G.A. Thiele, Antenna Theory

and Design, 2nd ed. New York: Wiley, 1998. [2] Thomas A. Milligan. 2nd Ed. Modern antenna

design. pp. 318-354 [3] A.K Bhattacharjee, S.R Bhadra, D.R. Pooddar and

S.K. Chowdhury. 1989. Equivalence of impedance and radiation properties of square and circular

micro strip patches antennas. IEE Proc. 136 (Pt, H, no. 4): 338-342.

[4] Kaymaram and L. Shafai, “Enhancement of micro

strip antenna directivity using double-superstreet configurations”, Electrical and Computer Engineering, Canadian Journal of vol. 32, issue 2, spring 2007, pages: 77-82

[5] Li, J. Y., Z.-Z. Oo, and L.-W. Li, “Improvement of

characteristics of micro strip antennas using unbalanced structures," IEEEAntennas and Wireless Propagat. Lett., Vol. 1, 71-73, 2002.

[6] H. Poor, “An Introduction to Signal Detection and

Estimation”, New York: Springer-Verlag, 1985, ch. 4.

[7] B. Smith, “An approach to graphs of linear forms

(Unpublished work style),” unpublished. [8] D. Orban and G.J.K. Moernaut, “The Basics of

Patch Antennas” IEEE Antennas and Wireless Propagat. Lett., Vol. 1, 56-59, 2002.

[9] J.Y. Li, Zaw-ZawOo, and Le-Wei Li,

“Improvement of characteristics of micro strip antennas using unbalanced structures,” IEEE Antennas and wireless Propagat. Lett, vol. 1, pp. 71-73, 2002.

[10] Kumar, G. and Ray, K.P., “Broadband Micro strip

Antennas”,Artech House, Inc, 2003. [11] C. J. Prior and P. S. Hall, “Micro strip disk antenna

with short-circuited annular ring”,Electronics Letters, Vol.21, pp. 719-721, 1985.

[12] R. Garg, P. Bhartia,I. Bahl, A. Ittipiboon, “Micro

strip Antenna Design Handbook”,ARTECH HOUSE, Boston 2001.

[13] Balanis, C.A., Advanced Engineering

Electromagnetics, John Wiley & Sons, New York, 1989.

AUTHOR PROFILES Mohammad MahabubAlamwas born in Dinajpur, Bangladesh in 1990. He received the B.Sc. degree on Electronics and Telecommunication Engineering from Rajshahi University of Engineering and Technology, Rajshahi-6204, Bangladesh. His research interests concerns the improvement of the bandwidth of the Micro strip Patch antenna.




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RifatAhmmedAoniwasborn in Kishoregonj, Bangladesh on 05 May, 1989. He received the B.Sc. Engineering degreein Electronics and Telecommunication Engineeringfrom Rajshahi University of Engineering &Technology, Rajshahi-6204, Bangladesh, in 2012. His research interest concerns the photonics& antenna related works.

Md. Toufikul Islamwas born in Pabna, Bangladesh in 11July, 1990. He received the B.Sc. Engineering degree on Electronics and Telecommunication Engineering from Rajshahi University of Engineering and Technology, Rajshahi-6204, Bangladesh. His research interests concerns the antenna related works.

Journal of Computing::Gain Improvement of Micro Strip ...€¦ · Patch antenna, Gain, Dual patch, Ku-band, Radiation pattern, GEMS Software. 1. INTRODUCTION . A MICROSTRIP ANTENNA

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