A Harmonic Suppression Microstrip Antenna for Mobile Communications Using Complementary Split Ring

Resonators

Binggang XIAO, Xiumin WANG, Jixiang ZHAO College of Information Engineering, China Jiliang University, Hangzhou, China

Email: bgxiao@cjlu.edu.cn

Abstract: A harmonic suppression microstrip patch antenna integrated with complementary split ring resona-tor (CSRR) etched in the ground plane is proposed and investigated. By integrating with the Complementary split ring resonator (CSRR), the microstrip antenna can suppress the second and the third harmonics associ-ated with the original structure while keeping good performance at the fundamental mode. The return loss at resonance frequency of 2.25GHz is improved by the inclusion of the CSRRs reaching 36dB compared with 20dB achieved by the original structure.

Keywords: Microstrip antenna; Complementary Split Ring Resonators; Mobile Communications 1 Introduction

Microstrip antennas are widely used in a variety of modern wireless communication systems since it was proposed in 1953[1]. Microstrip antenna has many out-standing advantages relative to other types of antennas: low weight, low profile with conformability, low manu-facturing cost and easy to be combined with circuit boards of cell phone, due to their extremely thin profiles (0.01- 0.05 free space wavelength) [2-4].

In active integrated microstrip antenna systems, the electromagnetic interference (EMI) caused by harmonic radiations is an very important problem[5]. The harmonic signals which are caused by nonlinearity of active compo-nents (e.g., amplifier, mixer, oscillator, and etc.) are gen-erally suppressed by a harmonic suppression filter be-tween the antenna and the power amplifier. The match of the system will be disturbed because of the extra intercon-nections between the antenna and the power amplifier[5]. However a harmonic suppression filter is difficult to be integrated in an active integrated antenna because it is a bulky and expensive component. To overcome these prob-lems, many other methods such as changing the shape of the antenna [6][7], cutting slots on the antenna[8] and using photonic bandgap structures[9] have been recently reported.

Recently metamaterials with simultaneously negative permeability and permittivity that were originally pro-posed by Veselago[10], have attracted the attention of sci-entific and engineering communities. Split Ring Resona-tors (SRRs) which are a pair of concentric annular rings with splits in them at opposite ends was proposed in[11] as a basic particle for the design of artificial negative mag-netic permeability media, By invoking the concepts of duality and complementarity, the complementary split-ring resonator (CSRR) has been proposed for metamate-rial design which is etched in the ground plane of planar transmission media[12]. The CSRRs provide a negative effective permittivity to the structure which leads to a

stopband characteristic appearing at the resonant fre-quency [12], corresponding to the negative permeability performance of SRRs. It is possible to suppress the un-wanted passband by designing a CSRR particle that reso-nates at a frequency which coincides with the unwanted spurious.

A microstrip patch antenna integrated with comple-mentary split ring resonator (CSRR) which is etched in the ground plane is proposed and investigated. It is dem-onstrated that the proposed antenna acts not only as a ra-diator but also a harmonic suppression filter. The second and third harmonic radiations were suppressed with im-proving the return loss at resonance from 20dB to 36dB by the inclusion of the CSRRs. The bandwidth of the pro-posed antenna is 1900MHz-2900MHz for VSWR<3, cov-ering personal communications system (PCS, 1850-1990 MHz), universal mobile telecommunications system (UMTS, 1920-2170 MHz), wireless local area network (WLAN, 2400-2484 MHz) and 3G Mobile Systems band. Since the CSRRs are etched in the ground plane under-neath the feedline of the microstrip antenna, it won’t add the size of the whole antenna system.

2 Antenna Configuration

The configuration of the proposed antenna is illus-trated in Fig.1. It is fabricated on Taconic CER-10 sub-strate which has a relative permittivity of 10 and a thick-ness of 1.27mm. A rectangle patch of width 45mm and length 20mm and 50Ω microstrip feed line are printed on the same side of the dielectric substrate. L and W denote the length and width of the dielectric substrate, respec-tively which are constant at 60mm here. The width of the microstrip feed line is fixed at 1.2mm to achieve 50Ω im-pedance. The conducting ground plane with a length of h1=20mm only covers the section of the microstrip feed line. The gap between the feed point and the ground plane is 3.5mm. It is shown in Fig.1(b) that the CSRRs are etched in the ground plane underneath the feedline of the

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Proceedings of Annual Conference of China Institute of Communications

microstrip antenna. The physical dimensions of the CSRRs here are d=0.3mm,w=2.7mm,l=4.1mm.The gap between two CSRRs is 3mm.The first CSRR is 5mm away from the edge of the ground. A reference microstrip antenna without etching CSRRs which has the same con-figuration with the proposed antenna as illustrated in Fig.1(a) is designed in order to compare.

(b)

Figure 1. (a) Geometry of proposed antenna (b) the ground plane with the CSRRs

3 Results and Discussion

Firstly, the CSRR loaded transmission lines with CSRRs etched in the ground plane as shown in Fig.1 (b) is inves-tigated. Fig.2 shows the frequency response of the CSRR loaded transmission lines which presents the stop band characteristics at 4.8GHz and 9.6GHz. The imulations are performed using the finite element method.

The simulated return loss of the reference antenna and the proposed antenna was illustrated in Fig.3. Fig.4 shows the simulated VSWR curves of the proposed antenna and s the reference antenna. It is shown in Fig.3 and Fig.4 that the proposed antenna can achieve the suppression of sec-ond and third harmonics which exit in the reference ante-

Figure 2. . Simulated S11 and S21 of the CSRRs

Figure 3. . Simulated return loss of the proposed antenna and the

reference antenna

Figure 4. Simulated VSWR of the proposed antenna and the reference antenna

nna. The return loss at resonance of the proposed antenna is significantly improved compared to the reference an-tenna which is pushed close to 38dB.

The simulated radiation patterns of the two antennas at

492978-1-935068-10-5 © 2010 SciRes.

Proceedings of Annual Conference of China Institute of Communications

2.25GHz (resonance frequency) are shown in Fig.5. It is clear from the results that the radiation patterns are not deteriorated by the inclusion of the CSRRs.

4 COnclusions

A harmonic suppression microstrip patch antenna inte

Figure 5. Simulated radiation patterns of the proposed antenna and the reference antenna at 2.25GHz (a) E-plane (b) H-

plane

grated with complementary split ring resonator (CSRR) isproposed and analyzed. The simulated results indicate that the proposed antenna acts not only as a radiator but also a harmonic suppression filter. The second and third harmonic radiations were suppressed. Moreover the app- lication improves the return loss at resonance compared with the reference antenna without deteriorating the ra- diation patterns. The size of the whole antenna system won’t be increased because the CSRRs are etched in the ground plane.

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[2] K. R. Carver and J. W. Mink, "Microstrip Antenna Technology," IEEE Trans. Antennas Propagat., Vol. 29, 1981，pp. 2-24.

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

[4] J. R. James and P. S. Hall, Handbook of Microstrip Antennas, Peter Peregrinus, London, 1989.

[5] Vesna Radisic, Yongxi Qian, and Tatsuo Itoh, IEEE Trans. Microwave Theory Tech, p.1901 (1998).

[6] A. F. Sheta and S. F. Mahmoud, “A novel H-shaped patch antenna,” in IEEE APS Int. Symp. Dig., vol. 2, July 2001, pp. 720–723.

[7] V. Radisic, Y. Qian, and T. Itoh, “Novel architectures for high-efficiency amplifiers for wireless applications,” IEEE Trans. Microwave Theory Tech., vol. 46, pp. 1901–1909, Nov. 1998.

[8] S. Kwon, H. K. Yoon, and Y. J. Yoon, “Harmonic tuning antennas using slots and short-pins,” in IEEE APS Int. Symp. Dig., vol. 1, July 2001, pp.118–121.

[9] Y. Horii and M. Tsutsumi, “Harmonic control by photonic bandgap on microstrip patch antenna,” IEEE Microwave Guided Wave Lett., vol. 9, pp. 13–15, Jan. 1999.

[10] V. G. Veselago, “The electrodynamics of substances with simultaneously negative values of ε and μ”, Soviet Physics Uspekhi, Vol. 10, pp. 509-514, January-February 1968.

[11] J. B. Pendry, A. J. Holden, D. J. Robbins, andW. J. Stewart, “Magnetism from conductors and enhanced nonlinear phenomena,” IEEE Trans. Microwave Theory Tech., vol. 47, pp. 2075–2084, Nov. 1999.

[12] F. Falcone, T. Lopetegi, J. D. Baena, R. Marqués, F. Martín, and M. Sorolla, “Effective negative ε stop-band microstrip lines based on complementary split ring resonators,” IEEE Microw.Wireless Compon. Lett., vol. 14, pp. 280–282, Jun. 2004.

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Proceedings of Annual Conference of China Institute of Communications