S. Sales, Tunable all- optical negative multitap microwave filters basedon uniform fiber Bragg gratings, Opt Lett 28 (2003), 1308–1310.

7. D. Liu, N.Q. Ngo, and S.C. Tjin, Microwave photonic bandpass filterusing a multiwavelength semiconductor-optical-amplifier ring laser,Opt Eng 46 (2007).

8. X. Liu, C. Lu, et al., Self-stabilizing effect of four-wave mixing and itsapplications on multiwavelength erbium-doped fiber lasers, IEEE Pho-ton Tech Lett 17 (2005), 2541–2543.

© 2009 Wiley Periodicals, Inc.

THE COMPACT QUAD-BAND PCBEMBEDDED ANTENNA FOR MOBILEHANDSET APPLICATIONS

Gyubok Park, Soonho Hwang, Sungkoo Park, Joonho Byun,and Austin S. KimTelecommunication R&D Center, Samsung Electronics Co., Ltd.,Yeongtong-gu, Suwon, Korea; Corresponding author:gyubok.park@samsung.com

Received 27 August 2008

ABSTRACT: A novel compact PCB printed quad-band antenna using acomposite loop and PIFA structure for mobile phones is presented. Theproposed antenna is composed of a meandered loop antenna and PIFAhaving the merits of the loop antenna and PIFA. The antenna element isprinted on the top ungrounded portion (34.5 mm (W) � 17 mm (L)) of a0.8-mm thick FR4 substrate of a mobile phone PCB. Despite the lowvolume and low profile of the antenna structure, it can fulfill the band-width requirements of the GSM900, DCS1800, PCS1900, andUMTS2100 systems with sufficiently high efficiency, thus making it apromising antenna candidate for future mobile terminals. The antennadesign was carried out using a high-frequency structure simulator(HFSS) by Ansoft, and the modeling structure of the mobile handsetswas obtained with the aid of the commercially available simulation soft-ware SEMCAD. The overall radiation pattern is suitable for mobile ap-plications. To demonstrate the proposed design, simulated and measuredresults are presented and discussed. © 2009 Wiley Periodicals, Inc.Microwave Opt Technol Lett 51: 1332–1336, 2009; Published online inWiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24309

Key words: printed antenna; mobile phone antenna; quad-band opera-tion; electrical coupling

1. INTRODUCTION

Modern portable communication systems have experienced highmarket demand in recent years, and the mobile handsets tend to besmaller and slimmer because of consumers’ needs and the multi-plicity of functions such as imaging, messaging, wireless computerlinks, wireless Internet, and digital mobile broadcasting.

Therefore, the space for the internal antenna is not bigenough to accommodate those functions in a mobile handset. Tofulfill the demand for this broad range of applications, modern

mobile handsets require antennas having multi-band resonance(more than triple band) and wide bandwidth characteristics evenin the insufficient antenna space. However, the aims of havingthe multi-band resonance and improving the bandwidth arecontradictory in the limited antenna area. Several techniqueshave been developed to have multi-band resonance and widebandwidth shrinking the antenna size, such as meandering,bending, and stagger tuning. In this article, we used a compositeloop and PIFA structure [1– 6]. The characteristic of the loopantenna is the wide bandwidth. However, it is hard to havemulti-band resonance using the loop antenna. In the case of thePIFA, it is possible to have multi-band resonance easily, but thebandwidth of the PIFA is very narrow. So, we use a compositeloop and PIFA structure to fulfill the multi-band resonanceand wide bandwidth. In this article, we present a novel com-pact PCB printed antenna for GSM900/DCS1800/PCS1900/UMTS2100 band operations. It occupies a compact area, 30 �15 mm2, only and does not need any thickness. To reduce theeffective antenna length for the resonance of the GSM900 bandin the insufficient antenna area (in other words, to increase theelectrical length of the antenna for GSM900 band), the electri-cal coupling between the ground of PCB and antenna elementswas used, and we used the electrical coupling between theantenna elements to enlarge the bandwidth in the high fre-quency band.

2. ANTENNA DESIGN

Figure 1 shows the combination structure of the proposed antenna.The antenna consists of a main resonator (loop antenna) and anadditional branch (PIFA). Figure 2 shows a detail dimension of thecircuit board and the proposed antenna. Antenna design was car-ried out using a high-frequency structure simulator (HFSS) byAnsoft. The PCB size is 45 mm (W) � 100 mm (L), and thedielectric material used for the PCB is 0.8-mm thick FR4 substrateof relative permittivity 4.4 F/m, and its conductivity is 0.0055 S/mat 900 MHz and 0.0105 S/m at 2000 MHz. The antenna element isprinted on the top ungrounded portion (34.5 mm (W) � 17 mm(L)) of a 0.8-mm thick FR4 substrate. The main resonator is amulti-band loop antenna tuned to operate at the DCS (1710–1880MHz), PCS (1850–1990 MHz), and UMTS2100 (1920–2170MHz) bands. To obtain the triple resonant frequencies, the lengthsand positions of the meander line were adjusted. In addition, tomake the resonance for GSM900 band and widen the bandwidthfor high bands, PIFA was used. The modeling structure shown inFigure 3 was obtained with the aid of the commercially availablesimulation software SEMCAD. SEMCAD is very useful for uswhen we consider complex housing structure.

3. SIMULATION AND MEASUREMENT RESULTS

Figure 4 shows the measured and simulated return loss of theproposed antenna. The difference between the measured and sim-ulated data is caused by inaccurate modeling data of LCD, speaker,vibrator, microphone, plastic case, FPCB (flexible PCB), and so

Figure 1 Combination structure of the proposed antenna. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com]

1332 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 5, May 2009 DOI 10.1002/mop

on. For return loss less than �10 dB (VSWR < 2), the achievedbandwidth is 875–970 MHz for the GSM900 band, which satisfiesthe operating bandwidth of the GSM900 band (880–960 MHz). Inthe high band (DCS1800, PCS1900 and UMTS2100), the achievedbandwidth is 1750–2200 MHz for return loss less than �10 dB(VSWR � 2) [1710–1750 MHz for return loss less than �7.5 dB(VSWR � 2.5)]. It is satisfies the operating bandwidth of theDCS1800, PCS1900, and UMTS2100 band (1710 –2170 MHz).We increased the electrical length for GSM900 band using theelectrical coupling between the elements of the antenna ((i) theleft part, (ii) lower part) and the ground of the PCB. The uppertwo branches are used to tune the resonance point of GSM900band and to generate the electrical coupling using the mainresonator (loop antenna) for enhancing the bandwidth of thehigh frequency band (DCS1800, PCS1900, and UMTS2100).Figure 5 and Figure 6 show the effect of the electrical couplingbetween the elements of the antenna and the ground of the PCBwith the corresponding S11. By adjusting the width a and b inthe Figure 2, we can make the electrical coupling between theground of PCB and the antenna element. It expands the elec-trical length of the antenna for GSM900 band. Figure 7 showsthe effect of the electrical coupling between the branch of theloop antenna and the branch of the PIFA with the corresponding

Figure 2 Detail dimension of the circuit board and the proposed antenna:(a) 3D view of the circuit board;(b) Geometry of the proposed antenna.[Color figure can be viewed in the online issue, which is available atwww.interscience.wiley.com]

Figure 3 Geometry of the mobile handset applied for the proposed antenna: (a) Bottom view without rear case; (b) Bottom view with rear case; (c) Sideview; (d) Real mobile handset. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com]

Figure 4 Measured and simulated return loss for the proposed antenna.[Color figure can be viewed in the online issue, which is available atwww.interscience.wiley.com]

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 5, May 2009 1333

Figure 5 Effect of the electrical coupling between the antenna element and the left ground of the PCB: (a) Simulation model and current distribution (gap:2.5 mm); (b) Simulation model and current distribution (gap: 0.5 mm); (c) Simulated return loss. [Color figure can be viewed in the online issue, which isavailable at www.interscience.wiley.com]

Figure 6 Effect of the electrical coupling between the antenna element and the lower ground of the PCB: (a) Simulation model and current distribution(gap: 3.5 mm); (b) Simulation model and current distribution (gap: 1.5 mm); (c) Simulated return loss. [Color figure can be viewed in the online issue, whichis available at www.interscience.wiley.com]

1334 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 5, May 2009 DOI 10.1002/mop

S11. By reducing the width c to 1 mm in the Figure 2, we canobtain the wider bandwidth at the high frequency band. Table 1also shows the enhanced bandwidth according to the change ofthe width c. We can obtain the enlarged bandwidth 60 MHz atthe DCS1800/PCS1900 band and 40 MHz at the UMTS2100band. By tuning the width c and d in the Figure 2, we caneffectively lower the antenna’s third resonant mode to be closeto the second resonant mode to form a wide bandwidth at about1800 MHz to cover the DCS1800/PCS1900 operation. The peakand average gains were measured in the anechoic 3D chamberand the corresponding radiation patterns in 3D plane are shownin Figure 8. Good radiation characteristics of the antenna over

the operating bands have also been observed. Table 2 shows theefficiency data of the whole frequency bands.

4. CONCLUSIONS

A new type of a compact printed antenna using a compositeloop and PIFA structure for a quad-band operation has beenproposed, and the antenna element is printed on the top un-grounded portion of a 0.8-mm thick FR4 substrate. The pro-posed antenna has the merits of the loop (wide bandwidth) andPIFA (multiple resonance and low profile) structure. In thelimited antenna area, we used the electrical coupling betweenantenna elements and the ground of the PCB to fulfill theelectrical length for GSM900 band and enhanced bandwidth ofthe DCS1800, PCS1900, and UMTS2100 band. The measuredresults are presented to show the validity of the proposedantenna. The obtained bandwidths meet the bandwidth require-ment of the GSM900, DCS1800, PCS1900, and UMTS2100mobile handsets application. In the future, the more accuratemodeling data of the LCD, speaker, vibrator, microphone, plas-tic case, and FPCB (flexible PCB) will lead to closer matchbetween simulations and measurement.

Figure 7 Effect of the electrical coupling between the elements of the antenna: (a) Simulation model and current distribution (gap: 2 mm); (b) Simulationmodel and current distribution (gap: 1 mm); (c) Simulated return loss. [Color figure can be viewed in the online issue, which is available at www.inter-science.wiley.com]

TABLE 1 Effect of the Electrical Coupling Between theBranch of the Loop Antenna and the Branch of the PIFA (forReturn Loss Less than �5 dB [VSWR ≤ 3])

OperatingFrequency Gap of Antenna

2 mm 1 mmEnhancedBandwidth

DCS1800/PCS1900 1753-1813 MHz 1755-1883 MHz About 60 MHzUMTS2100 2013-2078 MHz 2047-2150 MHz About 40 MHz

DOI 10.1002/mop MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 5, May 2009 1335

REFERENCES

1. K.L. Wong and K.P. Yang, Modified planar inverted F antenna,Electron Lett 34 (1998), 6–7.

2. W.P. Dou and Y.W.M. Chia, Novel meandered planar inverted-Fantenna for triple-frequency operation, Microwave Opt Technol Lett27 (2000), 58–60.

3. Y-X. Guo, M.Y.W. Chia, and Z.N. Chen, Miniature built-in multibandantennas for mobile handsets, IEEE Trans Antenna Propag 52 (2004),1936–1944.

4. P. Ciais, R. Staraj, G. Kossiavas, and C. Luxey, Design of an internalquad-band antenna for mobile phones, IEEE Microwave WirelessCompon Lett 14 (2004), 148–150.

5. B.K. Yu, B. Jung, H.J. Lee, F.J. Harackiewicz, and B. Lee, A folded andbent internal loop antenna for GSM/ DCS/ PCS operation of mobilehandset applications, Microwave Opt Technol Lett 48 (2006), 463–467.

6. S.H. Hwang, J.I. Moon, W.I. Kwak, and S.O. Park, Printed compactdual band antenna for 2.4 and 5 GHz ISM band applications, ElectronLett 40 (2004), 1568–1569.

© 2009 Wiley Periodicals, Inc.

MACRO PZT MEMS BASED WIDE-TUNABLE COUPLED LINE RESONATOR

Mahmoud Al Ahmad,1 S. Soulimane,1 R. Plana,1

K. van der Linden,2 and M. Riedel21 LAAS, CNRS, 7 avenue du Colonel Roche, 31077 Toulouse, Cedex4, France; Corresponding author: al-ahmad.mahmoud@ieee.org2 Argillon GmbH, Bahnhofstrasse 43, 96257 Redwitz, Germany

Received 28 August 2008

ABSTRACT: Resonators are core components in building advanced radiofrequency circuits and systems. Tunable resonators are highly needed foradaptive/tunable microwave components including filters and low-noisepower amplifiers, which are of great potential for the use in future multi-band multi-carrier systems. This letter reports a wide tunable two-coupledmicrostrip resonator. One of the lines is replaced by a macro MEMS piezo-electric actuator. When bias is applied, the coupling between the two linesis tuned; as a consequence, the center frequency is shifted. This work alsotakes a close look of the actuator’s mechanical resonance. © 2009 WileyPeriodicals, Inc. Microwave Opt Technol Lett 51: 1336–1338, 2009;Published online in Wiley InterScience (www.interscience.wiley.com).DOI 10.1002/mop.24308

Key words: bulk film; coupling; macro MEMS; piezoelectric materials;tunable circuit

1. INTRODUCTION

Tuning of microwave components/circuits is neither trivial nor aconventional task as often RF designers and developers used to do.For example, to design a filter for UMTS band, a redesign of anexisting filter could be performed when its center frequency andbandwidth are scaled by simply changing set of capacitancesand/or inductances values; or spacing and lengths of its stubs anddistributed lines [1].

Figure 8 Measured radiation patterns and gains for the proposed antenna in 3D plane: (a) GSM900 (Peak gain: 1.076 dBi, Avg. gain: �3.43 dBi); (b)DCS1800 (Peak gain 0.331 dBi, Avg. gain: �3.74 dBi); (c) PCS1900 (Peak gain: 0.957 dBi, Avg. gain: �3.51 dBi); (d) WCDMA2100 (Peak gain: �0.84dBi, Avg. gain: �3.16 dBi). [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com]

TABLE 2 Measured Average Efficiency in the Anechoic 3DChamber

Frequency (MHz) Efficiency (%) Directivity (dBi)

880 41 5.73925 46 5.15960 38 4.691750 37 5.261805 43 3.571850 39 3.211920 36 4.211990 41 4.242100 48 2.322130 45 3.42

1336 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 51, No. 5, May 2009 DOI 10.1002/mop