[IEEE 2014 International Conference on Informatics, Electronics & Vision (ICIEV) - Dhaka, Bangladesh...

Design of a Triple Band Microstrip Patch Antenna for Cellular and Wi-Fi Application

Khondaker Rahat Mozammel Huq1, Ahmed Shahnewaz Siraj2, Md. Imran Khan3, Nishat Shama4

[1 , 2 , 3]# World University of Bangladesh, 4American International University –Bangladesh,

Dhaka, Bangladesh. [email protected],[email protected],[email protected],[email protected]

Abstract—This paper presents a design and simulation of a

triple band microstrip patch antenna for cellular and Wi-Fi application. This will perform on the frequency 0.97 GHz, 1.35 GHz and 3.54 GHz. Ansoft HFSS software has been used for design and analysis. Before designing, the effect of frequency on length, width and the effect of dielectric substrate height on VSWR are analyzed. At 3.54 GHz the VSWR of this proposed antenna is -25.87 dB which clearly shows that this antenna will perform the best for Wi-Fi application. The proposed antenna having a compact size of 25 mm × 32 mm is simple and very easy to be integrated with microwave circuitry for low manufacturing cost. This microstrip antenna can also be made low profiled and conformal to fit on each individual platform, hence reducing or even eliminating antenna visual and radar signatures and increasing platform survivability significantly. The simulation also shows comparative differences between different feeding methods.

Key words —Antenna, Tri band, Microstrip, cellular, Wi-Fi, Ansoft HFSS

I. INTRODUCTION Antenna is a device used to transform an RF signal, traveling on a conductor, into an electromagnetic wave in free space. Antennas demonstrate a property known as reciprocity, which means that an antenna will maintain the same characteristics regardless if it is transmitting or receiving. Most antennas are resonant devices, which operate efficiently over a relatively narrow frequency band. An antenna must be tuned to the same frequency band of the radio system to which it is connected; otherwise the reception and the transmission will be impaired. When a signal is fed into an antenna, the antenna will emit radiation distributed in space in a certain way. A graphical representation of the relative distribution of the radiated power in space is called a radiation pattern .An antenna changes radio signals in the air into electricity, or vice versa. Antennas send signals, receive signals, or both. All NETGEAR wireless devices have an antenna, either a visible pole on the outside, or inside where you do not see it. The distance that an antenna sends (transmits) depends on the type, and the amount of power running through it. However, the distance from which an antenna can receive (or to be more exact, how faint a signal it can receive) is not based on power, but on how sensitive it is. Therefore, how far apart two antennas communicate depends on how powerful the transmitter is, as well as how sensitive the receiver's antenna is. Double-L slit compact antenna also experienced alike short of band notch at UNII mid band though covering dual band at 2.4 GHz and 5.2 GHz [1]. A printed monopole antenna for both satisfying WLAN and WiMAX application was proposed in [2]. This antenna tremendously covers wide range of radio spectrum from 2.01 to 4.27 GHz and 5.06 to 6.79 GHz but the peak gains are not sufficiently high (the gain of all frequency bands is less than 4 dBi). On other hand the flat-plate inverted-F antenna in [3] tightly cover Wi-Fi band at 2.4 and 5 GHz as well as mobile

WiMAX at 3.5 GHz. Curve Fitting based Particle Swarm Optimization (CFPSO) is presented for bandwidth improvement[11]. A high radiation efficient printed prototype S-shape slotted patch antenna is analyzed [12].A high-dielectric ceramic–polytetrafluoroethylene composite circular polarized square-shaped dual-resonant is designed [13]. A ground plane modified square shaped planar antenna has been proposed for UWB applications [14]. A high dielectric material substrate based antenna for UHF RFID, WiMAX, and WLAN applications is presented for high gain [15]. This paper is structured as follows. Section II part A describes effect of height of dielectric substrate, part B and part C shows antenna patch width and length calculation respectively. Section III part A shows the radiation pattern and part B is for VSWR, S parameter analysis and finally Section IV is conclusion.

II. ANTENNA DESIGN AND STRUCTURE

A. Effect of Height of Dielectric Substrate The input impedance and VSWR plots for two different

values of sustrate height h (0.159 cm and 0.318 cm) are shown in Figure 1 and 2 for L = 3.94 cm, W = 5.07 cm, �r = 2.55, With an increase in h from 0.159 cm to 0.379 cm, the following effects are observed.

Figure.1 Frequency Versus VSWR curve for h=0.379

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Figure. 2 Frequency Versus VSWR curve for h=0.159

With the increase in h, the fringing fields from the edges increase, which increases the extension in length ∆L and hence the effective length, thereby decreasing the resonance frequency. On the othe r hand with the increase in h, the W/ h ratio reduces which decreases �reff and hence increases the resona nce frequency. However, the effect of the increase in ∆L is dominant over the decrease in �reff. Therefore, the net effect is to decrease the resonance frequency. The directivity of the antenna increases marginally because the effective aperture area is increased marginally due to increase in ∆L. However, η decreases due to an increase in the cross-polar level for h=0.159 cm and 0.379 cm surface-wave propagation. Generally, h increases with an increase in the substrate thickness initially due to the increase in the radiated power, but thereafter, it starts decreasing because of the higher cross pol ar level and excitation of the surface wave [4]. The surface waves get excited and travel along th e dielectric substrate (i.e., between the ground plane and the dielectric-to-air interface due to total internal reflection). When these waves reach the edges of the substrate, they are reflected, scattered, and diffracted causing a reduction in gain and an increase in end-fire radiation and cross-polar levels. This also incr eases the cross coupling between the array elements. The excitation of surface waves is a function of �r and h. The power loss in the surface waves increases with an increase in the normalized thickness h/ λ0 of the substrate. The loss due to surface waves can be neglected when h satisfies the following criterion

h ≤ 0.3 λ0 /2π �r 1/2 (1)

�r = 4.4, is the dielectric constant, is the dielectric

constant, is the speed of light and is the wavelength .h << λ which is usually 0.003λ0 ≤ h ≤0.05λ0 [5]. For microstrip antenna applications in the microwave frequency band,

generally h is taken greater than or equal to 1/16th of an inch (0.159 cm) [23]. Now substrate height got a range of 0.159 cm ≤ h ≤ 0.379 cm for the operating frequency of 1.8 GHz. Therefore our selection of thickness of the substrate is 0.16 cm.

B. Width of the Patch For an RMSA to be an efficient radiator,width should be

taken equal to a half wavelength corresponding to the average of the two dielectric mediums (i.e., substrate and air) [6]

W = (v0 /2fr) × (2/1+ �r)

1/2 (2)

where v0 is the free-space velocity of light. Figure 3 shows that Width is 5.7cm at 1.8GHz. Figure 4 shows the dependancy on Effective dielectric constant in patch width of the antenna. Effective dielectric constant is found 4.149.Extended length is 0.07367 cm indicated by figure 5. figure 6 indicates how patch length is calculated.

∆L = 0.07367 cm; L=Leff -2∆L =3.944 cm

From figure 6, we got patch length L = 3.94 cm.

Figure.3 Frequency Versus Width


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C. Length of the Patch

Figure .4 Width Versus Effective dielectric constant

Figure.5 Effective dielectric constant Versus Extended length ∆L

Figure.6 Frequency Versus Length

Figure. 7 Probe Feed using dimension Calculated


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Figure.8 Line Feed using dimension Calculated Line feed and probe feed were designed using dimension calculated above. The antenna is designed using RT/Duroid software .In figure 9 first, two L-shaped stepped impedance components are designed to operate at 900/1800 MHz bands. Thereafter, a third resonant element is added for operation at the third band of 3500MHz. Height = 1.57mm is used to demonstrate the design concept. The width of middle arm antenna and left arm antenna is equal to 10mm to provide a suitable radiation aperture at the 900/1800MHz bands. The length of most right antenna is equal to 32mm and length of bottom arm is equal to 25 mm.

Figure .9 Top view of the triple band antenna designed on RT/Duroid

III. PERFORMANCE ANALYSIS

This antenna is designed on Ansoft HFSS for performance analysis.. Here for simulation the bottom box is used. At the bottom arm here probe feed are used. Radius of the coaxial pin is 0.5 mm that is wave port and radius of outer shell of coaxial cable is 1.5 mm.

Figure.10 Top 3D view of microstrip antenna for tri band on Ansoft HFSS

A. Radiation Pattern The radian pattern shows the signals directivity and power associated. At the radiation intensity is maximum

Figure. 11 Probe Feed Radiation Pattern (Angular Form)


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Figure. 11 Probe feed radiation pattern (rectangular form)

Figure.13 3D Polar Plot_(ang_deg(rETotal))

B. VSWR & S Parameter

Figure 14: Probe feed terminal S parameter This S parameter shows that the signal we feed at the input

terminal scattered at 0.97 GHz with power -12.6899 dB, 1.35 GHz with power -12.5051 dB and 3.54 GHz with power -25.8727 dB consequently (In above figure from left to right

Figure. 15 Probe feed (VSWR)


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Usually the bandwidth is the frequency range over which VSWR is less then 2, which corresponds to a return loss of 9.5 db or 11% reflected power. The BW of a single-patch antenna increases with an increase in the substrate thickness and a decrease in the �r of the substrate [7,8,9]. The BW is approximately 15% for �r= 2.2 and h = 0.1λ0. The �r can be chosen close to 1 to obtain a broader BW. With an increase in W also increases BW. The expressions for approximately calculating the percentage BW of the RMSA in terms of patch dimensions and substrate parameters is given by [10], increase in h will results in greater surface waves, spurious radiation and reduced directivity.Figure 16 and 17 show the electric field and magnetic field plot of the antenna respectively.

Figure.16 Electric Field Plot in Ansoft HFSS

Figure. 17 Magnetic Plot in Ansoft HFSS

IV. CONCLUSION The construction of the microstrip patch antenna was

simple in terms of paper and pencil. However, fabrication in Ansoft H FSS was far more difficult than anticipated before we started the thesis on Ansoft de signer. The resulted measured data supports our expected outcome. We successfully got the

frequency response at 0.97 GHz, 1.35GHz and 3.54 GHz with sufficient power. The design of microstrip antenna on Ansoft HFSS is an iteration process. The antenna does not strictly follow the formula or mathematical parametric analysis that has mentioned previous sections. Therefore the best way that we have used is trial and error base work on Ansoft HFSS. Our goal was to design a triple band microstrip patch antenna for cellular and Wi-Fi application and we achieve that very well for cellular application. But for Wi-Fi application it can be used because Wi-Fi range is 2.4 GHz to 5GHz. So in future bandwidth can be improved for Wi-Fi application with sufficient power obviously.

REFERENCES [1] T. H. Kim, and D. C Park, “Compact Dual-Band Antenna with

Double L-Slits for WLAN Operations,” IEEE Antennas and Wireless Propagation Letters, vol. 4, pp. 249-252, May 2005.

[2] C. Y. Pan, T. S. Horng, W. S. Chen, and C. H. Huang, “Dual Wideband Printed Monopole Antenna for WLAN/WiMAX Applications,” IEEE Antennas and Wireless Propagation Letters, Vol 6, pp. 149-151, Jan. 2007.

[3] L. Pazin, N. Telzhensky, and Y. Leviatan, “Multiband Flat-Plate Inverted-F Antenna for Wi-Fi/WiMAX Operation,” IEEE Antennas and Wireless Propagation Letters, Vol. 7, pp. 197-200, Mar. 2008

[4] Zurcher, J. F., and F. E. Gardiol, Broadband Patch Antennas, Norwood, MA: Artech House, 1995.

[5] C.A. Balanis, “Antenna Theory: Analysis Design”, Third Edition, Chapter 14 - Microstrip Antennas, ISBN 0-471-66782-X Copyright © 2005 Jhon Wiley & Sons, Inc.

[6] I. J. Bhal and P. Bhartia, Microstrip Antennas, Artech House, Dedham, MA, 1980.

[7] James, J. R., and P. S. Hall, Handbook of Microstrip Antennas, Vol. 1, London: Peter Peregrinus Ltd., 1989.

[8] Derneryd, A. G. and A. G. Lind, ‘‘Extended Analysis of Rectangular Microstrip Resonator Antennas,’’ IEEE Trans. Antennas Propagation, Vol. AP–27, November 1979, pp. 846–849

[9] James, J. R., P. S. Hall, and C. Wood, Microstrip Antenna Theory and Design, London: Peter Peregrinus, 1981.

[10] Girish Kumar, K. P. Ray, “Broadband Microstrip Antenna,” Artech House, Boston, London, 2003, pp. 38.

[11] M. T. Islam,M. Moniruzzaman, N. Misran, and M. N. Shakib, ‘Curve fitting based particle swarm optimization for UWB patch antenna’, Journal of Electromagnetic Waves and Applications, vol. 23, no. 17–18, pp. 2421–2432, 2009.

[12] M. Habib Ullah, M. T. Islam, J. S. Mandeep, “Printed Prototype of A Wideband S Shape Microstrip Patch Antenna for Ku/K Band Applications”, Applied Computational Electromagnetics Society Journal, 28(4), 307-310, 2012.

[13] M. T. Islam, M. Habib Ullah, “Analysis of A Dual Resonant Multiple Split Ring Patch Antenna”, International Journal of Circuit Theory and Applications, 2013.

[14] R. Azim, M. T. Islam, N. Misran, S. W. Cheung, and Y. Yamada, ‘Planar UWB antenna with multi-slotted ground plane’, Microwave and Optical Technology Letters, vol. 53, no. 5, pp. 966–968, 2011.

[15] M. R. Ahsan, M. T. Islam, M. Habib Ullah, “Bandwidth Enhancement of a Dual Band Planar Monopole Antenna using Meandered Microstrip Feeding” The Scientific World Journal, 2014(856504), pp: 1-8.


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