JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 34

Optimization of Wideband Antenna Using Microstrip Patch: An impact on Wireless Communications Samiran Pramanik1, Taniya Guha1, Indrani Nath1 and Nirmalendu Bikas Sinha1

Abstract—In this paper authors explore wideband antenna using microstrip patch having a 2:1 VSWR with impedance bandwidth of 34% covering the 5.2/5.8 GHz WLAN, HIPERLAN2, and HiSWANa communication bands. The large bandwidth is obtained by adding a mirror image of G shaped microstrip patch directly over the substrate. The antenna occupies an overall dimension of 20 mm × 40 mm × 1.055 mm, when printed on a substrate of dielectric constant 4.4 F/m. It exhibits good characteristics and moderate gain in the entire operating band. Details of the design along with experimental and simulation results are presented and discussed. Finally this paper addresses the current question regarding the optimization of wideband antenna on wireless communication. Index Terms - Broadband microstrip antenna, WLAN, Omnidirectional, HIPERLAN2, and HiSWANa. .

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1.

INTRODUCTION

In the present scenario the mobile wireless communication systems such as notebook computers , PDAs, digital notepad and so on, demand connectivity with greater transmitting and receiving speeds through wireless local network (WLAN). The design of antenna in this regard becomes more acute and critical as it requires some special properties such as small size, broadband and omnidirectionality.To meet these requirements printed microstrip antennas are the best candidates as they possess low profile and cost. In spite of these advantages they have constrict bandwidth which necessitates careful measures to be taken to achieve ————————————————

• Prof. NirmalenduBikas Sinha, corresponding author is with the Department of ECE and EIE , College of Engineering & Management, Kolaghat, K.T.P.P Township, Purba- Medinipur, 721171, W.B., India. • Prof. Samiran Pramanik is with the Department of ECE, College of Engineering & Management, Kolaghat, K.T.P.P Township, PurbaMedinipur, 721171, W.B., India. • TaniyaGuha is with the Department of ECE, College of Engineering & Management, Kolaghat, K.T.P.P Township, Purba- Medinipur, 721171, W.B., India. • Indrani Nath is with the Department of ECE, College of Engineering & Management, Kolaghat, K.T.P.P Township, Purba- Medinipur, 721171, W.B., India.

broadband characteristics.. In general, the impedance bandwidth of a traditional microstrip antenna is only a few percent, e.g., about 5% [1].If the bandwidth ofmicrostrip antenna could be widen, it would be very useful for commercial application such as 3G wireless system, wireless local area network (WLAN) etc. There are various proposed techniques for increasing bandwidth of microstrip patch antenna such as increasing patch height and decreasing substrate permittivity, using multilayer structure [2], use of multiple resonators [3], aperture coupling [4],stacking[5], [6], E-shaped patch [7], and modifications in the feed [8]– [10], use of coupled parasites [11],etc.Garget al. have reported a single-band microstrip ring antenna [12] in which impedance matching is brought about by loading a metal strip on the ring structure without affecting the cross-polarization characteristics. The bandwidths of single patch antennas can also be increased by implementing internal structures such as shorting pins [13], or slots [14-15]. In this paper, a new electromagnetically coupled

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JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 35

broadband,

planar

impedance-matching

scheme

is

achieved by using simple rectangular strips to form a

20 mm × 10 mm and the gap dimension (g) between the two microstrip is, g = 9 mm.

mirror image of G for Wireless Communications. The electromagnetically coupled broadband antenna has 2:1

L

VSWR, impedance bandwidth of 34% from 4.6 to 6.5GHz covering

IEEE

802.11a

(5.15-5.35,

4

w4

5.725-5.825GHz),

g

HIPERLAN2 (5.45-5.725 GHz),and HiSWANa (5.15-5.25 GHz) communication bands.

L

w3

L1

2. GEOMETRY OF THE ANTENNA

3

w2 L2

The geometry of the proposed antenna is shown in Fig.1

w1

(a). For achieving good impedance characteristics four rectangular strips with dimensions L1 × w1 = 21 mm × 2mm, L2 × w2 =5 mm × 2 mm, L3 × w3 = 16 mm × 2 mm, L4 × w4 = 7 mm × 2 mm are fabricated over the substrate in a manner such that they form a G shaped (its mirror image) microstrip patch, where the dielectric constant of the

substrate

is

4.4

F/m

and

its

size

Fig.1 (b) Dimensions of the microstrip patch (w1 = w2 = w3 = w4 = 2 mm and L1 = 21 mm, L2 = 5 mm, L3 = 16 mm, L4 = 7 mm, g = 9 mm).

is

20mm×40mm×1mm.

3. ANTENNA DESIGN Microstrip Patch

20 mm

Using equation 1 the parameters
 , ,  , are

determined hence the substrate was chosen and the patch was incorporated above it. The configuration of the proposed antenna is shown in Fig.1 (a). The substrate

Ground Plane

40 mm

chosen for realizing the antenna has
 4.4 /,

0.0022 and thickness  1 mm. The antenna was

analyzed using full wave electromagnetic simulation software CST Microwave Studio 2009. For a dielectric substrate of thickness h, microstrip line width w and relative permittivity
 the effective permittivity is:

h=1 mm




Substrate

12

12 
  1  
  1 1   



… … 1

With
 4.4 /,  1mm,  2mm we get


3.34254 . Approximate antenna resonant frequency can be calculated from following equation:

Fig.1 (a) Geometry of the proposed antenna. The antenna is electromagnetically coupled using a 50 Ώ

$% $


&' … … 2 * ( )
 

microstrip transmission line fabricated on the same

The obtained frequency approximated from the guided

substrate. The ground plane dimension is optimized as

wavelength is about 5.2 GHz. The width and length of

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JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 36

the coplanar ground is 20 mm and 40 mm respectively. The dimensions of the microstrip line L1, L2, L3, L4 and resonant behavior of the proposed antenna. Hence their parametric study is considered. Fig.2 shows the effect of variation of strip width on return loss characteristics of the antenna. An optimum width of w = 2 mm is selected for achieving the maximum bandwidth of the antenna. The effect of

Return Loss (dB)

w1, w2, w3, w4 as shown in Fig.2, have a crucial role in

g=9 g=8 g=7 g=6 g=5

various microstrip patch length on the return loss characteristics is shown in Fig.3. If we increase L1 keeping the other dimensions constant, g decreases. This

Frequency (GHz)

results in a poor return loss. The cause for this

Fig.3. Return loss characteristics of proposed antenna for

phenomenon is increased coupling between the two

parametric study by varying g. Other parameters are w1

microstrip patches with decrease in the gap (g). Hence

= w2= w3 = w4 = 2 mm and L1 = 21 mm L2 = 5 mm L3 =

with the increase in gap dimension (g) the return loss

16 mm L4 = 7 mm.

increases. Table-1 indicates the design parameters and their

Return Loss (dB)

corresponding values.

W1=W2=W3=W4=0.5 W1=W2=W3=W4=1.0 W1=W2=W3=W4=1.5 W1=W2=W3=W4=2.0 W1=W2=W3=W4=2.5

Table I: Design parameters and their corresponding values

Parameters w1 w2 w3 w4 L1 L2 L3 L4 g

Value (mm) 2 2 2 2 21 5 16 7 9

Frequency (GHz) Fig.2. Return loss characteristics of proposed antenna for parametric study by varying w1, w2, w3, w4. Other parameters are L1 = 21 mm L2 = 5 mm L3 = 16 mm L4 = 7 mm and g = 9 mm.

4. RESONANCE AND RADIATION CHARACTERISTICS The return loss plot of the final design is given in Fig.4 which shows that the antenna covers the 5.2/5.8 GHz WLAN, HIPERLAN2, and HiSWANa communication band. It is clear that the antenna has one resonance, between 5 and 5.4 GHz. In the 5.2 GHz band, the S11≤ 10 dB, bandwidth is about 1.9 GHz (4.6-6.5 GHz) or about 34% of the center frequency of 5.5 GHz, So it meets the bandwidth requirement for IEEE 802.11a (5.15-5.35,

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JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 37

5.725-5.825

GHz),

HIPERLAN2

(5.45-5.725

CONCLUSION

GHz)

HiSWANa (5.15-5.25 GHz) communication bands.

A simple electromagnetically coupled wideband antenna structure

can

be

used

for

5.2/5.8

GHz

WLAN,

HIPERLAN2, and HiSWANa applications. Bandwidth Return Loss (dB)

enhancement is achieved due to employment of matching rectangular strips forming a shape of mirror image of ‘G’ on the substrate. The antenna has characteristics of compact size, a simple structure, good Omni directionality and has satisfied input return loss, bandwidth of 34% from 4.6 to 6.5 GHz band. The wideband antenna also provides good radiation pattern Frequency (GHz)

at 5.2 GHz, and possesses good potential for broadband communication with antenna gain of 3.8 dBi.

Fig.4.Return loss characteristics of the proposed antenna The principal patterns at 5.2 GHz are shown in Fig.5. The width of each microstrip patch is kept same to keep the current distribution symmetrical on either side. As the opposing currents on either sides of the strip cancel the fields along the axis at the far-field, we get a symmetrical radiation pattern. This makes the antenna (at 5.2 GHz) very useful in the Omni-directional communication systems, such as WLAN, HIPERLAN2, and HiSWANa communication bands. Simulated polar plot Reference polar plot

REFERENCES [1] K .R. Carver and J.W. Mink, “Microstrip Antenna Technology”, IEEE trans. Antenna Propagation, vol. 29.pp. 2-23, 1981. [2] Z.F. Liu, P.S. Kooi, L.W. Li and M. S. Leong, and T.S. Yeo, ”A method for designing broadband Microstrip antennas in multilayered planar structures”, IEEE trans. Antenna Propagation, vol. 47, no. 9, pp. 14161420, Sept. 1999. [3] G. Kumar and K.C. Gupta, ”Broadband Microstrip antennas using additional resonators gap coupled to the radiating edges”, IEEE trans. Antenna Propagation, vol. 32, no. 12, pp. 1375-1379, Dec.1984. [4] D.M. Pozar and B. Kaufman,” Increasing the bandwidth of a microstrip antenna by proximity coupling”, Electron. Lett, vol. 23, no. 8, pp. 368-369. 1987. [5] S.D. Targonski, R.B. Waterhouse and D.M. Pozar,” Design of wideband aperture stacked patch microstrip antennas”, IEEE trans. Antenna Propag, vol.46, no. 9, pp. 1245-1251, Sept. 1998. [6] M.A. Martin, B.S. Sharif and C.C. Tsimenidis, “Probe fed stacked patch antenna for wideband applications”, IEEE trans. Antenna Propag, vol. 55, no. 8, pp. 2385-2388, Aug. 2007.

Fig.5. Principal Plane simulated radiation pattern at 5.2 GHz

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JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 38

[7] F. Yang, X.-X. Zhang, Z. Ye and Y. RahmatSamii,”Wideband E-Shaped patch antenns for wireless communications”, IEEE trans. Antenna Propagation, vol. 49, no. 7, pp. 1094-1100, Jul. 2001. [8] Y.-X. Guo, M.Y.W. Chia Z.N. Chen and K.M. Luk,” Wide-band L-probe fed circular patch antenna for conical pattern radiation”, IEEE trans. Antenna Propagation, vol. 52, no. 4, pp. 1115-1116, Apr.2004. [9] J. Park, H.-g. Na and S.-h. Baik,” Design of wideband aperture stacked microstrip antennas”, IEEE Antennas Wireless Propag. Lett., vol. 3, pp. 117-119, 2004. [10] C.-L. Mak, H. Wong, and K.-m. Luk,” High gain and wide-band single layer patch antenna for wireless communications”, IEEE transVeh. Technol., vol 54, no .1, pp. 33-40, Jan. 2005. [11] C.K. Anandan, P. Mohanan and K.G. Nair,” Broadbandgap coupled microstrip antenna”, IEEE trans. Antenna Propagation, vol. 38, no. 10, pp. 1581-1586, Oct. 1990. [12] R.Garg and V.S. Reddy,” Edge feeding of microstrip ring antenna”, IEEE trans. Antennas Propagation, vol. 51, no. 8, pp. 1941-1946, Aug. 2003. [13] S.-C. Pan and K.L. Wong,” Dual- frequency triangular microstrip antenna with a shorting pin”, IEEE trans. Antenna Propagation, vol. 45, pp. 18891891, Dec. 1997. [14] T. Huynh and K.F. Lee,” Single layer single patch wideband microstrip antenna”, Electronics Letters, vol. 31, no. 16,pp. 1310-1312, Aug. 1995 [15] K.F. Lee, K.M. Luk, K.F. Tong, S.M. Shung, T. Huynh and R.Q. Lee,” Experimental and Simulation studies of the co-axially fed U-slot rectangular patch antenna”. IEEE Proc. Microwave. Antenna Propagation, vol. 144, no. 5, pp. 354-358, 1997.

Asst. Prof. Samiran Pramanik received the B. Tech degree in Electronics and communication Engg. from W.B.U.T, West Bengal and M. Tech degrees in Electronics and communication Engg. (specialization in microwave) Burdwan University, India, in 2007 and 2009, respectively. He is currently working towards the Ph.D degree in Electronics and Telecommunication Engineering at BESU. Since 2010, he has been associated with the College of Engineering and Management, Kolaghat. W.B, India where he is currently an Asst.Professor is with the department of Electronics & Communication Engineering & Electronics & Instrumentation Engineering. His current research Interests are in the area, MIMO, multiuser communications,Microwave /Millimeter wave based Broadband Wireless Mobile Communication Wireless 4G communication. He has published large number of papers in different international Conference. Taniya Guha is pursuing B-Tech in the department of Electronics & Communication Engineering at College of Engineering & Management, Kolaghat under WBUT in 2011, West Bengal , India. Her areas of interest are Microwave, broadband wireless communication, Digital Electronics. She has published some papers in international Journals.

Indrani Nath is pursuing B-Tech in the department of Electronics & Communication Engineering at College of Engineering & Management, Kolaghat under WBUT in 2011, West Bengal, India. Her areas of interest are Microwave, broadband wireless communication, Circuit theory. She has published some papers in international Journals.

Prof. Nirmalendu Bikas Sinha received the B.Sc (Honours in Physics), B. Tech, M. Tech degrees in RadioPhysics and Electronics from Calcutta University, Calcutta,India,in1996,1999 and 2001, respectively. He is currently working towards the Ph.D degree in Electronics and Telecommunication Engineering at BESU. Since 2003, he has been associated with the College of Engineering and Management, Kolaghat. W.B, India where he is currently an Asst.Professor is with the department of Electronics & Communication Engineering & Electronics & Instrumentation Engineering. His current research

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JOURNAL OF TELECOMMUNICATIONS, VOLUME 7, ISSUE 2, MARCH 2011 39

Interests are in the area of signal processing for highspeed digital communications, signal detection, MIMO, multiuser communications,Microwave /Millimeter wave based Broadband Wireless Mobile Communication ,semiconductor Devices, Remote Sensing, Digital Radar, RCS Imaging, and Wireless 4G communication. He has published more than 50 number of papers in different international Conference, proceedings and journals.He is presently the editor and reviewers in different international journals.

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