Published in IET Microwaves, Antennas & Propagation Received on 17th October 2007 Revised on 4th November 2008 doi: 10.1049/iet-map.2008.0204 ISSN 1751-8725 Triple-frequency meandered monopole antenna with shorted parasitic strips for wireless application W.-C. Liu 1 M. Ghavami 2 W.-C. Chung 1 1 Department of Aeronautical Engineering, National Formosa University, 64 Wenhua Road, Huwei, Yunlin 632, Taiwan, Republic of China 2 Department of Electronic Engineering, King’s College London, Strand, London WC2R 2LS, UK E-mail: wencliu@nfu.edu.tw Abstract: The performance of a triple-frequency meandered-strip monopole antenna for wireless application is presented. The proposed antenna comprises of a microstrip-fed monopole with an additional meandered strip and a ground plane with three protrudent strips on the opposite side of the substrate. By adding these shorted parasitic strips to this monopole, good impedance matching for multi-band application is obtained. Tuning effects of the additional shorted strips to the different resonant modes were examined and prototype of the proposed antenna had been constructed and experimentally studied. The measured results explore a broadband triple-frequency operation covering the required bandwidths of the PCS-1900/UMTS-2100 and the 2.4/5.2/5.8 GHz WLAN standards, a near-directive radiation pattern and a good antenna gain for this design. 1 Introduction Portable wireless communications have evolved at an astonishing rate during the last decade. There is much present interest in developing a system with the ability to integrate more than one communication standards in a single compact module. To meet the demands, the future communication terminal antennas must not only be with a multi-band operation, but also have a simple structure, compact size and easy integration with the circuit. Such an antenna can therefore be used simultaneously in different frequency bands for different mobile services. However, the difficulty of antenna design challenges engineers when the number of operating frequency bands increases. So far, with the usage of multi-band characteristics in wireless communication system, many promising techniques such as the planar monopole antennas [1–4], planar patch antennas [5–7], planar inverted-F antennas [8–10] and coplanar waveguide-fed antennas [11–14] have been proposed. However, in these designs most efforts were focused on etching the patch shape for producing a multi-resonant mode and a large plane is usually used for the ground. Thus, this mostly results in the requirements of either greater complexity in antenna shapes or larger antenna size for practical applications. In this paper, referring to reported works [15–17], that have shown that a microstrip-fed monopole antenna with a shorted parasitic strip can excite dual- and broadband operation, a simple triple-frequency design of the microstrip-fed monopole antenna consisting of a meandered-strip element and a ground plane with three shorted parasitic strips is presented. By properly adding strips to the ground and carefully selecting the positions and lengths of these strips, good triple-broad impedance bandwidths as well as radiation characteristics suitable for multi-band wireless communication systems such as the personal communication system (PCS)-1900, universal mobile telecommunication system (UMTS)-2100 and 2.4/5.2/5.8 GHz IEEE 802.11 wireless local area network (WLAN) operations can be achieved. 2 Antenna design and simulation Fig. 1 illustrates the geometry of the proposed meandered monopole antenna with shorted parasitic strips for 1110 IET Microw. Antennas Propag., 2009, Vol. 3, Iss. 7, pp. 1110–1117 & The Institution of Engineering and Technology 2009 doi: 10.1049/iet-map.2008.0204 www.ietdl.org