Novel MTM Patch Antenna for Broad-Band Portable Units

Transcription

1 Merit Research Journal of Enineerin, Pure and Applied Sciences Vol. 2(1) pp , September, 2014 Available online Copyriht 2014 Merit Research Journals Oriinal Research Article Novel MTM Patch Antenna for Broad-Band Portable Units Mohammad Alibakhshi-Kenari Abstract School of Electrical and Communication Enineerin, Shahid Bahonar University of Kerman, Iran In this paper, a squeeze broad-band antenna based on the composite riht-left handed transmission line (CRH-T) structure with enhancement ain is proposed and investiated. With CRH metamaterial technoloy embedded, the proposed squeeze broad-band antenna is presented with best in bandwidth, size, efficiency and radiation patterns. To realize characteristics of the antenna, the printed I-shaped aps into the rectanular radiation patches are used. This antenna is constructed of the four unit cells, also presented antenna is desined from 2.2 GHz to 3.05 GHz which correspondin to 32% bandwidth. The overall size of the presented antenna is 22mm 7mm 0.8mm or 0.16λ0 0.05λ λ0 at the operatin frequency f=2.2ghz (where λ0 is free space wavelenth). The radiation peak ain and the maximum efficiency which occurs at 3.05GHz are 4.1dBi and 68.86%, respectively. Keywords: Squeeze antenna, Broad-band antenna, Composite Riht/eft- Handed Transmission ine (CRH-T), Metamaterial (MTM) INTRODUCTION Microstrip patch antennas have found extensive application in wireless communication systems due to their low profile, low cost, relatively simple fabrication, compatibility with planar circuitry, planar structures, and unidirectional radiation capability. Antenna miniaturization is extremely important for modern wireless communication systems. The conventional approach for miniaturizin the antenna size is to print the radiator on a hih dielectric substrate. However, because of the capacitive nature of the patch eometry and the existence of stron impedance contrast between the antenna substrate and the free space surroundin reion, a lare amount of electric enery is trapped inside the dielectric material resultin in a narrow antenna bandwidth and radiation loss. To overcome these problems we usin of the MTM technoloy and the printed patch technique. These ways the antenna can be miniaturized while the system bandwidth and radiation characteristics are automatically improved. In recent years, metamaterials have been used for the patch antenna substrate to miniaturize it. Recently, novel antennas have been desined by usin composite riht/left-handed transmission line (CRH-T) metamaterials (ai and Itoh, 2004; Herraiz Martínez et al., 2008). Unlike traditional riht-handed (RH) transmission materials, metamaterials based on lefthanded (H) transmission lines (Ts) have unique features of anti-parallel roup and phase velocities (ai and Itoh, 2004; Herraiz-Martínez et al., 2008; Mao et al., 2005). Pure H Ts cannot be implemented due to the existence of RH parasitic effects that occur naturally in practical H Ts. CRH-T structures have been proposed, which also include RH effects. In this article, a squeeze broad-band patch antenna filled with CRH

2 002 Merit Res. J. En. Pure Appl. Sci. Fiure 1. The infinitesimal equivalent circuit model of the CRH-T composed of N unit cells. Fiure 2. Proposed Antenna: Equivalent circuit model of the CRH MTM antenna for one unit cell. structures is proposed. CRH-T Theory The concept of HMs was first theorized by the Russian physicist (Veselao, 1968). Metamaterials (MTM) are artificial structures that can be desined to exhibit specific electromanetic properties not commonly found in nature. Recently, MTM with simultaneously neative permittivity (ε) and permeability (µ), more commonly referred to as left-handed (H) materials, have received substantial attention in the scientific and enineerin communities. The unique properties of HMs have allowed novel applications, concepts, and devices to be developed. HMs are considered to be a more eneral model of composite riht/left hand (CRH) structures, which also include riht-handed (RH) effects that occur naturally in practical HMs. HMs support electromanetic waves with roup and phase velocities that are anti-parallel, known as backward waves. Since resonant structures such as SRRs are lossy and narrow-banded, they are often difficult to implement for microwave applications. The eneral T approach provides insiht into the physical phenomena of HMs and provides an efficient desin tool for H applications. The T approach of HMs, presented in this article, has led to nonresonant structures with lower loss and wider bandwidth. In particular, MTM with RH and H properties known as CRH MTM have led to the development of several novel microwave devices. As illustrated in fiurev1 the composite riht/lefthanded (CRH) transmission line (T) (Caloz and Itoh, 2003) is a T composed of the periodic repetition of a unit cell comprisin a series inductance and a shunt capacitance as well as a series capacitance and a shunt inductance. The series capacitance and shunt inductance provide left-handedness (anti-parallel phase and roup velocities) (Caloz and Itoh, 2003; Smith et al., 2000) at lower frequencies, whereas the series inductance and shunt capacitance provide the riht-handedness (parallel phase and roup velocities) at hiher frequencies. The CRH-T is intrinsically non-resonant and thereby presents the advantaes of lower loss and broader bandwidth than resonant-type left-handed (H) materials (Smith rt al., 2000). In addition, the CRH T appropriately represents real distributed H structures (Caloz and Itoh, 2003), which have inevitable distributed parasitic series inductance and shunt capacitance, in contrast to the idealized H T which represents only a series capacitance and shunt inductance in the unit cell. The CRH-T can be implementin in the two cases, balance and unbalance cases, and there is the unique phenomenon of vanishement of the bandap

3 Kenari 003 (a) (b) Fiure 3. Confiuration of the presented squeeze broad-band patch antenna composed of the four unit cells based on CRH MTM-T. a) Top view, b) Isometric view. between the H and RH modes in the balanced CRH T. In the particular balanced case when the inductance and capacitance ratios of the H and RH components of the unit cell are identical, that is, = R, is satisfied, and the bandap vanishes. It C CR should be noted that at β = 0 the wavelenth is infinite ( λ = ) and the structure is perfectly homoeneous. In the balanced CRH T, we can have a seamless transition between the H and RH ranes with infinite-wavelenth wave with enery R transmission ( v 0 ).In contrast, when ( = ) C CR is not satisfied (unbalanced case), the roup velocities become zero, and there is therefore no propaation ( v = 0 ). Proposed antenna desin procedure In this paper, we employin printed planar technique for our antenna desin, since printed planar structures are ood nominee for antenna desin because of their advantaes which include foot print area reduction, loss less and non-discrete values (Mohammad et al., 2012; Mohammad et al., 2012). A squeeze broad-band patch antenna with improvement ain based on CRH-T presented in here, which consists of four unit cells while each unit cell will be desined by two rectanular radiation patches with printed I-shaped aps into patches, and the spiral inductor accompanyin metallic via connected to the round plane. Fiure 2 display equivalent circuit model of each cell as CRH unit cell. The antenna structure is based on a composite riht-left handed (CRH) transmission line (T) model used as a periodic structure. Because the lowest mode of operation is a H mode, the propaation constant approaches neative infinity at the cut off frequency, and reduce its manitude as frequency is increased. Makin use of this phenomenon, an electrically lare but physically small antenna can be developed. Fiure 3 shows confiuration of the proposed antenna, in this structure, port 1 is excited with input sinal and port 2 is matched with 20Ω load impedance. In this article, we usin of MTM technoloy and the printed planar patches approach that results to foot print area reduction of the proposed antenna. Fiure 3 shows confiuration of the recommended antenna constructed of the four unit cells based on CRH-T structure that

4 004 Merit Res. J. En. Pure Appl. Sci. Fiure 4. Simulated reflection coefficient S 11. (a) (b) (c) Fiure 5. The Radiation ains of the proposed antenna in elevation ( Φ = 0 deree). a) 2.2, b) 2.5, and c) 3.05 GHz. was desined on a FR_4 substrate, with a dielectric constant of 4.6, a thickness of 0.8mm and Tan D= By means of the I-shaped aps and spiral inductors with shortin via-hole connectin to round plane, the series capacitance (C ) and shunt inductance ( ) can be easily implemented in a squeeze fashion. In each unit cell, the series capacitance (C ) is developed by two the printed I- shaped aps into radiation patches, and the shunt inductance ( ) is resulted from the spiral inductor shorted to the round plane throuh the metallic via. The

5 Kenari 005 structure possesses the riht-handed parasitic effects that can be seen as shunt capacitance (C R ) and series inductance ( R ). The shunt capacitance is mostly come from the ap capacitance between the patch and the round plane, and the unavoidable currents that flow on the patch establish series inductance, which indicates that these capacitance and inductance cannot be inored. The proposed desin procedure keeps the overall size of the unit cell compact while aims at reducin the ohmic loss to improve ain and radiation efficiency. Overall size of this antenna is 0.16λ λ λ 0 at the operatin frequency f=2.2ghz where λ 0 is the free space wavelenth. With choosin smaller distance between printed I-shaped aps edes, will be obtained wide bandwidth from 2.2 GHz to 3.05 GHz which correspondin to 850 MHz bandwidth. Furthermore, with appropriate selectin of the number unit cells (N) constructin antenna structure and structural parameters, will be achieved ood radiation performances. The ain and the efficiency of the proposed antenna are chaned from 0.54dBi-4.1dBi and from 9.6%-68.86%, respectively, into frequency band GHz, that shown ood radiation characteristics. This antenna can support all cellular frequency bands from 2.2 GHz to 3.05 GHz, usin sinle or multiple feed desins, which eliminates the need for antenna switches. These entire attributes make the proposed antenna based on CRH-T is well suitable for the wireless communication applications and mobile handsets. SIMUATION RESUTS AND DISCUSSION The proposed MTM antenna is desined as a CRH antenna where the substrate has dielectric constant ε = 4.6, thickness h=0.8mm and Tan D= Squeeze broad-band recommended antenna is simulated by usin ADS full-wave simulator. The simulated S11 parameter displayed in Fiure 4 and simulated radiation ain patterns in 2.2, 2.5 and 3.05 GHz are plotted in Fiure 5. The radiation patterns are unidirectional characteristics. The simulated ains at 2.2, 2.5, 3.05 GHz are 0.54, 2.63, and 4.1dBi, respectively. The simulated radiation efficiency is 9.6% at 2.2GHz, 43.18% at 2.5GHz, and 68.86% at 3.05 GHz. The four unit cells squeeze broad-band antenna is desined from 2.2 GHz to 3.05 GHz and this antenna exhibit ood matchin between this frequency bands for 20Ω impedance port. The physical lenth, width and heiht of the suested antenna are 22mm, 7mm and 0.8 mm (0.16λ0 0.05λ λ0), respectively. The ain and the radiation efficiency of this antenna are varies from 0.54dBi to 4.1dBi and from 9.6% to 68.86%, respectively, into the frequency rane 2.2 GHz-3.05 GHz. r CONCUSION In this paper, we introduced a new concept of antenna size reduction with wide bandwidth accompanyin enhancement ain based on a MTM desin methodoloy. A practical squeeze, broad-band and hih ain antenna with a simple feed structure and planar circuit interation possibilities has been demonstrated. Overall size of the recommended antenna is 22mm 7 mm 0.8 mm or 0.16λ0 0.05λ λ0 at the operatin frequency f=2.2 GHz where λ 0 is free space wavelenth. A return loss below -10dB from 2.2 GHz 3.05 GHz was obtained which correspondin to 32% bandwidth. The peak ain and the maximum efficiency of the proposed antenna which occurs at f=3.05 GHz, are 4.1dBi and 68.86%, respectively. This antenna has the advantaes of wideband, compact size, hih ain, unidirectional radiation patterns and simple implementation. The recommended antenna can be used for portable units such as mobile handsets and wireless communication applications. ACKNOWEDGEMENT The author would like to express his sincere thanks to Iran Telecommunication Research Center, i.e.; ITRC (Contract number 6987/500/T), the microwave and millimeter wave laboratory of the Amirkabir University of Technoloy (Tehran Polytechnic) and the antenna laboratory of the K. N. Toosi University of Technoloy. REFERENCES Caloz C, T Itoh (2003). Novel microwave devices and structures based on the transmission line approach of meta-materials, in IEEE-MTT Int. Symp. Di., June, pp Herraiz-Martínez FJ, V González-Posadas, E Garcia-Munoz, D Seovia-Varas (2008). Multifrequency and dual-mode patch antennas partially filled with left-handed structures, IEEE Trans. Antennas Propa., vol. 56, no. 8, pp , Au. ai CC, T Itoh (2004). Composite riht/left-handed transmission line metamaterials, IEEE Microw. Ma., vol. 5, no. 3, pp , Sep. Mao SG, S Chen, CW Huan (2005). Effective electromanetic parameters of novel distributed left-handed microstrip lines, IEEETrans. Microw. Theory Tech., vol. 53, no. 4, pp , Apr. V. Mohammad A, Masoud M, Ahmad H (2012). Compact and Ultra Wide Band Planar Antenna Based on the Composite Riht/eft-Handed Transmission ine Accompanyin Improvement First Iranian Conference on Electromanetic Enineerin (ICEME 2012), Tehran, Iran, December. Mohammad A, Masoud M, Hadi N (2012). A New Miniature Ultra Wide Band Planar Microstrip Antenna Based on the Metamaterial Transmission ine 2012 IEEE Asia-Pacific Conference on Applied Electromanetics (APACE 2012), December 11-13, Melaka, Malaysia. Smith DR, WJ Padilla, DC Vier, SC Nemat-Nasser, S Schultz (2000). Composite medium with simultaneously neative permeability and permittivity, Phys. Rev. ett., vol. 84, no. 18, pp , May Veselao V (1968). The electrodynamics of substances with simultaneously neative values of ε and µ, Soviet Physics Uspekhi, vol. 10, no. 4, pp