Bandwidth Enhancement of a U-Slot Patch Antenna Using Embedded HIS Structure

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Available online atwww.ispacs.com/acte

Advanced Computational Techniques in Electromagnetics Volume 2012, Year 2012, Article ID acte-00118, 4 Pages

doi: 10.5899/2012/acte-00118 Research Article

ADVANCED

C

OMPUTATIONAL

T

ECHNIQUES IN

ELECTROMAGNETICS

Bandwidth Enhancement of a U-Slot Patch Antenna Using Embedded

HIS Structure

Archana Agrawal

1,∗

, Anurag Sharma

1

, Pramod Kumar Singhal

2

1_{Department of Electronics and Communication, ITM Bhilwara, India} 2_{Department of Electronics and Communication, MITS Gwalior, India}

Copyrightc 2012 Archana Agrawal, Anurag Sharma, and Pramod Kumar Singhal. This is an open access article distributed under theCreative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

This paper proposes a new generation of antenna that applies metamaterial as a base construction. With the use of dual band high impedance surface (HIS) structures, the bandwidth, return loss, and gain of U-slot patch antenna is improved at resonant frequencies 2.24 GHz and 5.8 GHz. The proposed new modified U-slot antenna has dual band impedance bandwidth from about 2.1886 to 2.27 GHz and 5.6149 to 7.2259 GHz. From the simulation result it was found that the upper frequency band of the proposed antenna lies in the band of 5.725∼5.825 GHz regulated by IEEE 802.11a (upper band) and can be used for bluetooth and WLAN applications. We perform this analysis on structures which composed of rectangular lattice patches periodic arrangements. All the dimensions and shapes of the unit cell geometry are optimized in order to get a broad bandwidth and high return loss. The lattice structure comprises of an array of 7×5 rectangular patches embedded in the substrate.

Keywords:HIS; U-slot patch antenna; FSS.

1. Introduction

R

ecentdevelopments in fast and rigorous full wave simula-tors and the concurrent availability of inexpensive manu-facturing techniques for intricate shape and composite materials provide the opportunity to revolutionize the traditional design to new one. To provide multiple functions, it is practical to in-tegrate systems of different frequencies into a single product. Developing a single unit with multi-frequency bands as well as wide band will certainly save considerable circuit area and is also required for accurately transmitting the voice, data, video, and multimedia, concurrently. Therefore, how to enhance the bandwidth and frequency bands [1–7] has became an important issue in the antenna design field. The FSS structure has a phe-nomenon with high impedance surface that reflects the plane wave in-phase and suppresses surface wave thus improving the radiation efficiency, bandwidth, and gain, and reducing the side and back lobe levels in its radiation pattern. For more than four decades the FSS has applications in the areas of filter [8–13], reflectors, absorbers [14–16], polarizers [17], planar metamate-rials [18], and artificial magnetic conductors [19–21].

In this paper, a U-slot patch antenna is designed first to over-come the problem of narrowband and to achieve dual band oper-ation at resonant frequencies of 2.24 and 5.8 Ghz. The

dimen-∗_{Corresponding author}

E-mail addresses: archana.agrawal@yahoo.com (A. Agrawal), shara-nurag@gmail.com(A. Sharma),pks 65@yahoo.com(P.K. Singhal)

sions of U-slot are varied and the feed location was changed until good results were observed.

In the later part, we propose a new U-slot patch antenna em-bedded with a lattice of an array of 7×5 rectangular patches without connection with the ground plane. Array of patches without via connection to the ground plane exhibit a high impedance with an exactly zero degree reflection phase at the resonance frequency. We have known that, there is a problem with most of proposed HIS structures because they present a shift of the resonant frequency versus the incidence angle [22]. But in comparison with conventional antenna type placed above a metal ground plane, the antenna placed above the HIS has smoother radiation profile, less power wasted in the back-ward direction, better return loss, and higher gain and directiv-ity [23,24]. In simulations, the characteristics of U-slot patch antennas were obtained by using the Ansoft high-frequency structure simulator (HFSS).

2. The U-slot patch antenna with embedded HIS

structure

The dimensions of a U-slot patch antenna are taken as 76×52 mm2_{. The thickness of substrate is taken as 3.4 mm .The}

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2 A. Agrawal et al./Bandwidth Enhancement Using Embedded HIS Structure.

Figure 1:A U-slot patch antenna.

Figure 2: A modified U-slot patch antenna with embedded HIS at height of H=2.9 mm from ground plate.

U-slot are 28.4 and 15 mm, respectively. The width of slot is kept as 2 mm. In our studies, a coaxial line with a characteristic impedance of 50 ohms is used as the feed of the U-slot patch an-tenna. The inner conductor of the coaxial line is attached on the top patch going through the dielectric substrate, and the outer conductor is shorted to the metallic plate on the other side of the patch antenna. The dimensions and layout of this U-slot ra-diator is shown in Fig.1. For the proposed new antenna the FSS is constructed at a height of H=2.9 mm from ground plate. The FSS structure is constructed with the rectangular shaped patches array to improve the bandwidth and gain of the U-slot patch an-tenna. The detail dimensions of the FSS embedded U-slot patch antenna is shown in Fig.2. The rectangular shaped patches FSS has dimensions of 3.5 mm×4 mm. The gaps between the array elements are also shown in Fig.4.

In optimizing the onset of two resonant frequencies of 2.24 GHz and 5.8 GHz, the change of geometrical parameters W1

and W2and H can be used to find the best bandwidth. Figs.3

and4show the detail dimensions of unit cell and periodic array of rectangular shaped patch HIS structure.

3. Simulated results with and without HIS

struc-ture

The simulated result of the U-slot patch antenna is shown in Fig.5with and without HIS structure. Simulation results were investigated by checking the impedance matching with better than -10 dB return loss.

The result shows that the resonant frequency of the patch is

Figure 3:Detail of a unit cell element of HIS structure.

Figure 4:Detail dimensions of HIS structure array embedded at a height H= 2.9 mm from ground plate.

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Advanced Computational Techniques in Electromagnetics,Volume 2012, Year 2012, 4 Pages. 3

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Figure 6: Radiation pattern of U-slot patch antenna with HIS structure; (a) at resonant frequency 2.24 GHz, (b) at resonant frequency 5.84 GHz, (c) at resonant frequency 6.64 GHz.

located at approximately 2.24, 5.84, and 6.6 GHz, with the -10 dB dual impedance bandwidth from about 2.1886 to 2.27 GHz and 5.6149 to 7.2259 GHz . From the simulation result it was found that the frequency band lies in the band of 5.725∼5.825 GHz regulated by IEEE 802.11a (upper band) and can be used for bluetooth and WLAN applications. It was also observed that as the parameters of the rectangular patches are changed or made square shaped, the resonant frequencies shifts and there is a decrease in bandwidth and return loss.

The simulated and measured radiation patterns of the pro-posed antenna are shown in Fig.6at different resonant frequen-cies. The radiation patterns shown have low side lobe levels and back lobe levels.

4. Conclusion

A technique for the gain and bandwidth enhancement of U-slot patch antenna using embedded HIS structure was presented. The parameters of the HIS structure (spacing, width, length, and number of the patches) and the thickness of the substrate were optimised using Ansoft HFSS to obtain the maximum gain and bandwidth. While the HIS structure reduced the surface wave, the bandwidth and gain enhancement was mainly because of coupling between the patch and the HIS structure. From simula-tion results, it is found that the bandwidths have been improved near the resonant frequencies of 2.24 and 5.8 GHz for the U-slot patch antenna implanted with a HIS consisting of regular rectangular patches elements array.

Acknowledgment

I highly acknowledge the authorities of Dr. B.R. Ambedkar In-stitute for their support to carry out my work successfully.

References

[1] F. Yang and Y. Rahmat-Samii, “Refection phase characterizations of the EBG ground plane for low profile wire antenna applications,”IEEE Transactions on Antennas and Propagation, vol. 51, no. 10, pp. 2691– 2703, 2003.

[2] J. Liang and H.Y. David Yang, “Radiation characteristics of a microstrip patch over an electromagnetic bandgap surface,”IEEE Transactions on Antennas and Propagation, vol. 55, no. 6, pp. 1691–1697, 2007.

http://dx.doi.org/10.1109/TAP.2007.898633

[3] D. Sievenpiper, L. Zhang, R.F.J. Broas, N.G. Alexopolous, and E. Yablonovitch, “High-impedance electromagnetic surfaces with a for-bidden frequency band,”IEEE Transactions on Microwave Theory and Techniques, vol. 47, no. 11, pp. 2059–2074, 1999.

http://dx.doi.org/10.1109/22.798001

[4] X.L. Bao, G. Ruvio, M.J. Ammann, and M. John, “A novel GPS patch antenna on a fractal hi-impedance surface substrate,”IEEE Antennas and Wireless Propagation Letters, vol. 5, no. 1, pp. 323–326, 2006.

http://dx.doi.org/10.1109/LAWP.2006.878900

[5] H. Mosallaei and K. Sarabandi, “Antenna miniaturization and band-width enhancement using a reactive impedance substrate,”IEEE Trans-actions on Antennas and Propagation, vol. 52, no. 9, pp. 2403–2414, 2004.

(4)

4 A. Agrawal et al./Bandwidth Enhancement Using Embedded HIS Structure.

[6] A.P. Feresidis, G. Goussetis, S. Wang, and J.C. Vardaxoglou, “Arti-ficial magnetic conductor surfaces and their application to low-profile high-gain planar antennas,”IEEE Transactions on Antennas and Propagation, vol. 53, no. 1, pp. 209–215, 2005.

[7] B.A. Munk, R.J. Luebbers, and R.D. Fulton, “Transmission througha 2-layer array of loaded slots,”IEEE Transactions on Antennas and Prop-agation, vol. AP22, no. 6, pp. 804–809, 1974.

[8] B.A. Munk, Frequency Selective Surfaces Theory and Design, New York, Wiley, 2000.

http://dx.doi.org/10.1002/0471723770

[9] F.R. Yang, K.P. Ma, Y. Qian, and T. Itoh, “A uniplanar compact photonic-bandgap (UC-PBG) structure and its applications for microwave cir-cuits,”IEEE Transactions on Microwave Theory and Techniques, vol. 47, no. 8, pp. 1509–1514, 1999.

http://dx.doi.org/10.1109/22.780402

[10] C.-N. Chiu, C.-H. Kuo, and M.-S. Lin, “Bandpass shielding enclosure design using multipole-slot arrays for modern portable digital devices,”

IEEE Transactions on Electromagnetic Compatibility, vol. 50, no. 4, pp. 895–904, 2008.

http://dx.doi.org/10.1109/TEMC.2008.2004560

[11] M.S. Zhang, Y.S. Li, C. Jia, and L.P. Li, “Signal integrity analysis of the traces in electromagnetic-bandgap structure in high-speed printed cir-cuit boards and packages,”IEEE Transactions on Microwave Theory and Techniques, vol. 55, no. 5, pp. 1054–1062, 2007.

http://dx.doi.org/10.1109/TMTT.2007.895413

[12] T.K. Wu and S.W. Lee, “Multiband frequency selective surface with mul-tiring patch elements,”IEEE Transactions on Antennas and Propagation, vol. 42, no. 11, pp. 1484–1490, 1994.

http://dx.doi.org/10.1109/8.362790

[13] G.I. Kiani, K.L. Ford, K.P. Esselle, A.R. Weily, C. Panagamuwa, and J.C. Batchelor, “Single-layer bandpass active frequency selective surface,”

Microwave and Optical Technology Letters, vol. 50, no. 8, pp. 2149– 2151, 2008.

http://dx.doi.org/10.1002/mop.23615

[14] G.I. Kiani, K.L. Ford, K.P. Esselle, A.R. Weily, and C.J. Panagamuwa, “Oblique incidence performance of a novel frequency selective surface absorber,”IEEE Transactions on Antennas and Propagation, vol. 55, no. 10, pp. 2931–2934, 2007.

[15] B.A. Munk, P. Munk, and J. Pryor, “On designing Jaumann and circuit analog absorbers (CA absorbers) for oblique angle of incidence,”IEEE Transactions on Antennas and Propagation, vol. 55, no. 1, pp. 186–193, 2007.

[16] A.K. Zadeh and A. Karlsson, “Capacitive circuit method for fast and efficient design of wideband radar absorbers,”IEEE Transactions on An-tennas and Propagation, vol. 57, no. 8, pp. 2307–2314, 2009.

[17] R. Ulrich, “Far-infrared properties of metallic mesh and its complemen-tary structure,”Infrared Physics, vol. 7, no. 1, pp. 37–50, 1967.

http://dx.doi.org/10.1016/0020-0891(67)90028-0

[18] N. Engheta and R.W. Ziolkowski,Metamaterials: Physics and Engineer-ing Explorations, Hoboken/Piscataway, NJ: Wiley-IEEE Press, 2006.

[19] D.J. Kern, D.H. Werner, A. Monorchio, L. Lanuzza, and M.J. Wilhelm, “The design synthesis of multiband artificial magnetic conductors using high impedance frequency selective surfaces,”IEEE Transactions on An-tennas and Propagation, vol. 53, no. 1, pp. 8–17, 2005.

[20] J. McVay, N. Engheta, and A. Hoorfar, “High impedance metamaterial surfaces using Hilbert-curve inclusions,”IEEE Microwave and Wireless Components Letters, vol. 14, no. 3, pp. 130–132, 2004.

http://dx.doi.org/10.1109/LMWC.2003.822571

[21] J. Bell and M. Iskander, “A low-profile archimedean spiral antenna using an EBG ground plane,”IEEE Antennas and Wireless Propagation Let-ters, vol. 3, no. 1, pp. 223–226, 2004.

http://dx.doi.org/10.1109/LAWP.2004.835753

[22] M. Hosseini, A. Pirhadi, and M. Hakkak, “A novel AMC with little sen-sitivity to angle of incidence using an optimized jerusalem cross FSS,”

Progress In Electromagnetics Research, vol. PIER 64, pp. 43–51, 2006.

http://dx.doi.org/10.2528/PIER06061301

[23] J.M. Bell, M.F. Iskander, and J.J. Lee, “Ultrawideband hybrid EBG/Ferrite ground plane for low-profile array antennas,”IEEE Trans-actions on Antennas and Propagation, vol. 55, no. 1, pp. 4–12, 2007.

[24] Q.-R. Zheng, B.-Q. Lin, Y.-Q. Fu, and N.-C. Yuan, “Characteristics and applications of a novel compact spiral electromagnetic band-gap (EBG) structure,”Journal of Electromagnetic Waves and Applications, vol. 21, no. 2, 199–213, 2007.

http://dx.doi.org/10.1163/156939307779378844

Archana Agrawal is B.E., M.Tech, and pursuing Ph.D. in the field of Electronics and Communication Engineering. She is working as an assistant professor in the Department of Electronics and Commu-nication at ITM Bhilwara and has a total teaching experience of 8 years. Her area of interest lies in the field of antenna de-signing and microwave engineering.

Anurag Sharma received bachelor of engineering degree in Electronics & Communication Engineering from ITM, Bhilwara, under University of Rajasthan in 2008 with honors. He has experience of 3 years as a lecturer. His area of inter-est is antenna design, VLSI design, dig-ital Electronics, computer networks, and wireless communication.