1008 IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 3, MARCH 2010
[17] S. K. Khamas, “Moment method analysis of an Archimedean spiral printed on a layered dielectric sphere,” IEEE Trans. Antennas Propag., vol. 56, pp. 345–352, Feb. 2008.
[18] S. K. Khamas, P. L. Starke, and G. G. Cook, “Design of a printed spiral antenna with a dielectric superstrate using an efficient curved segments moment method with optimization using marginal distribu-tions,” in Proc. Inst. Elect. Eng. Microw, Antennas Propag., Aug. 2004, vol. 151, pp. 315–320.
[19] M. Abramowitz and I. A. Stegun, “Handbook of mathematical func-tions with formulas,” in Graphs, and Mathematical Tables. Wash-ington, DC: Government Printing Office, 1964.
Miniature Internal Penta-Band Monopole Antenna for Mobile Phones
Chia-Ling Liu, Yi-Fang Lin, Chia-Ming Liang, Shan-Cheng Pan, and Hua-Ming Chen
Abstract—A compact T-slit monopole antenna with slotted ground plane
in the mobile phone for penta-band operation is proposed. In this config-uration, the antenna comprises a T-slit monopole printed on the top un-grounded portion of an FR4 substrate of small size of47 5 4 mm and a slotted ground plane etched on the back side of the substrate of size of
47 10 mm . In addition, an inverted-L copper strip is soldered to the
end edge of the monopole for extending the electrical length of the antenna for GSM band; that is, the proposed antenna occupies a small volume of
47 10 5 mm inside the mobile phone and is suitable to operate as
an internal antenna. By controlling the related parameters, the proposed antenna can resonates at different operating bands to cover GSM850/900 and DCS/PCS/UMTS operations independently.
Index Terms—Mobile phone, penta-band, T-slit monopole antenna.
I. INTRODUCTION
Recently with the rapid development of cellular communication, various types of antennas for mobile phones have been extensively presented and the trend of the mobile phones is getting smaller and slimmer because of the consumer’s needs and the multiplicity of functions. Conventional internal antennas for the mobile phones applications are generally in forms of monopole antennas because it can provides a wide impedance bandwidth [1]–[6]. These monopole antennas generally use two separate resonant paths of different lengths operated at their quarter-wavelength modes to cover the mobile phone’s operating bands.
In this communication, we present a promising compact penta-band monopole antenna with an occupied volume of10 2 47 2 5 mm3 in the mobile phone to operate GSM (824–894/890–960 MHz),
Manuscript received March 11, 2009; revised August 30, 2009. First pub-lished December 28, 2009; current version pubpub-lished March 03, 2010. This work was supported by the National Science Council of Taiwan under Contract NSC 97-2221-E-151-010.
C.-L. Liu, Y.-F. Lin, C.-M. Liang, and H.-M. Chen are with the Institute of Photonics and Communications, National Kaohsiung University of Applied Sciences, Kaohsiung 807, Taiwan (e-mail: linyf@cc.kuas.edu.tw; hmchen@cc. kuas.edu.tw).
S.-C. Pan is with the Department of Computer and Communication, Shu-Te University, Yen Chau, Kaohsiung 824, Taiwan.
Color versions of one or more of the figures in this communication are avail-able online at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TAP.2009.2039309
Fig. 1. Configuration of the T-shaped slit monopole antenna with slotted ground plane for mobile phone application.
DCS (1710–1880 MHz), PCS (1850–1990 MHz), and UMTS (1920–2170 MHz) bands. The proposed antenna is easily printed on a thin substrate at low cost and fabricated by a bending metal plate shown a very low profile of 5 mm. The low profile of the antenna allows it very promising to be embedded inside the mobile phone as an internal antenna. In order to determine the performance of varying design parameters on bandwidth and resonance frequency, parametric study is carried out using simulation software HFSS and experimental results. Detailed design considerations of the proposed antenna are described in this article.
II. ANTENNACONFIGURATION
Fig. 1 shows the configuration of the T-slit monopole antenna with slotted ground plane for mobile phone application. A 0.8-mm thick FR4 substrate of relative permittivity 4.4 and of size110 2 50 mm2is used as the system circuit board with a ground plane of the same size. The dimensions of the system circuit board and ground plane considered here are practical for general mobile phones. In Fig. 1(a), the antenna comprises a T-slit monopole printed on the top ungrounded portion of an FR4 substrate of small size47 2 5:4 mm2 and a slotted ground plane etched on the back side of the substrate of size47 2 10 mm2. In this study, an inverted-L copper strip is soldered to the end edge of the monopole for extending the electrical length of the antenna for GSM band. For the inverted-L copper strip, it comprises a horizontal section of size37 2 2 mm2and a vertical section of size5 2 2 mm2. In addition, a T-slit is etched on the monopole radiator to realize two major current paths and achieving an additional resonant mode. A 50-microstrip feed line printed on the top side of the system circuit board has a length of 35 mm and a width of 1.5 mm. Fig. 1(b) shows the dimensions of the pattern of the ground plane on the back side of the substrate. The pattern comprises a narrow straight slot and a narrow slit. By varying the length of the slit, the various coupling energy between the feed line and the pattern in the ground plane can results in another excited resonant mode. Detailed dimensions of the antenna are given in Fig. 1.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 58, NO. 3, MARCH 2010 1011
Fig. 9. Measured and simulated antenna gain and radiation efficiency of the proposed antenna. (a) The lower band for GSM operation. (b) The upper band for DCS/PCS/UMTS operation.
slots. The different coupling effects of the slotted structure make it con-trollable for the excitation of a quarter-wavelength resonant modes at about 1795, 1920, and 2045 MHz, respectively. The two excited res-onant bands cover GSM and DCS/PCS/UMTS operations for the pro-posed antenna in this study.
REFERENCES
[1] K. L. Wong, G. Y. Lee, and T. W. Chiou, “A low-profile planar monopole antenna for multiband operation of mobile handsets,” IEEE Trans. Antennas Propag., vol. 51, pp. 121–125, 2003.
[2] Y. F. Lin, H. M. Chen, and K. L. Wong, “Parametric study of dual-band operation in a microstrip-fed uniplanar monopole antenna,” Proc. Inst. Elect. Eng. Microw. Antennas Propag., vol. 150, no. 6, pp. 411–414, 2003.
[3] Z. N. Chen, M. Y. W. Chia, and M. J. Ammann, “Optimization and comparison of broadband monopoles,” Proc. Inst. Elect. Eng. Microw. Antennas Propag., vol. 150, no. 6, pp. 429–435, 2003.
[4] C. H. Wu and K. L. Wong, “Printed compact S-shaped monopole an-tenna with a perpendicular feed for penta-band mobile phone applica-tion,” Microw. Opt. Technol. Lett., vol. 49, pp. 3172–3177, 2007. [5] K. L. Wong and P. Y. Lai, “Wideband integrated monopole slot
an-tenna for WLAN/WiMAX operation in the mobile phone,” Microw. Opt. Technol. Lett., vol. 50, no. 8, pp. 2000–2005, 2008.
[6] R. A. Bhatti and S. O. Park, “Octa-band internal monopole antenna for mobile phone applications,” Electron. Lett., vol. 44, no. 25, pp. 1447–1448, 2008.
[7] S. I. Latif, L. Shafai, and S. K. Sharma, “Bandwidth enhancement and size reduction of microstrip slot antennas,” IEEE Trans. Antennas and Propag., vol. 53, pp. 994–1003, 2005.
Printed Single-Strip Monopole Using a Chip Inductor for Penta-Band WWAN Operation in the Mobile Phone
Kin-Lu Wong and Shu-Chuan Chen
Abstract—A single-strip monopole capable of generating two wide
oper-ating bands at about 900 and 1900 MHz covering GSM850/900/1800/1900/ UMTS penta-band WWAN operation in the mobile phone is presented. The monopole has a simple structure of an inverted-L shape to be printed on the no-ground region of the system circuit board of the mobile phone. By simply embedding a chip inductor at the proper position in the strip monopole, the first two resonant modes of the monopole can have a frequency ratio of about 1 to 2 (instead of 1 to 3 for the traditional monopole) to respec-tively cover the desired wide 900 and 1900 MHz bands. In addition, the total strip length can be less than the required 0.25 wavelength (about 0.17 wave-length in this design) for the fundamental resonant mode excitation of the proposed monopole; this behavior is owing to the embedded chip inductor compensating for the increased capacitance seen at the feeding point with the decreasing strip’s resonant length. The SAR of the proposed monopole placed at the bottom position of the mobile phone is found to meet the SAR limit for practical applications.
Index Terms—Handset antennas, internal mobile phone antennas,
mo-bile antennas, multiband antennas, WWAN antennas.
I. INTRODUCTION
It has been known that, by embedding a chip inductor, the monopole can have decreased resonant length for achieving its fundamental or lowest resonant mode excitation [1]–[3]. This behavior is owing to the additional inductance contributed by the embedded chip inductor to compensate for the increased capacitance resulting from the decreased resonant length of the antenna. Related works on the shortened dipole and monopole with this kind of inductive loading have also been avail-able in the open literature. They include the shortened dipole with the inductive element placed in series with each radiating arm of the dipole [4] and the multi-branch monopole with one of its branches end-loaded with a dense meandered section as the inductive end section [5]. It has also been shown that the chip inductor should be embedded near the feeding point of the monopole [1] where the excited surface currents are strong for the fundamental resonant mode. In this case, the required resonant length is usually less than 0.2 wavelength for generating the fundamental resonant mode of the monopole. Also, it is found that the required resonant length of the second resonant mode of the monopole will be decreased as well such that the frequency ratio of the first two resonant modes maintains about 1 to 3, similar to that of the traditional monopole or dipole [6]–[8]. Hence, in order to obtain two wide bands at about 900 and 1900 MHz to cover GSM850/900/1800/1900/UMTS wireless wide area network (WWAN) operation, two separate radiating strips are usually required for the internal WWAN antenna for mobile phone applications [1], [9].
In this communication, we propose a printed single-strip monopole using a chip inductor for penta-band WWAN operation in the mobile phone. The embedded chip inductor can result in a decreased resonant length for the fundamental resonant mode excitation of the monopole. It can also generate an additional resonant mode such that the first two
Manuscript received April 14, 2009; revised May 28, 2009. First published December 31, 2009; current version published March 03, 2010.
The authors are with the Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung 80424, Taiwan (e-mail: wongkl@ema.ee.nsysu. edu.tw; wongkl@mail.nsysu.edu.tw)
Color versions of one or more of the figures in this communication are avail-able online at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/TAP.2009.2039324
