A Novel Low-Profile Broadband Dual-FrequencyPlanar Antenna for Wireless Handsets.pdf

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 56, NO. 4, APRIL 2008 1155 A Novel Low-Profile Broadband Dual-Frequency Planar Antenna for Wireless Handsets RongLin Li, Senior Member, IEEE, Bo Pan, Student Member, IEEE, Joy Laskar, Fellow, IEEE, and Manos M. Tentzeris, Senior Member, IEEE Abstract—A new low-profile broadband dual-frequency planar antenna is developed for wireless handsets. The dual-frequency an- tenna consists of a two-strip monopole for the 2-GHz band and a planar monopole for the 5-GHz band. The developed antenna features a low profile due to the introduction of an S-strip and a T-strip which are separately printed on the two sides of a thin sub- strate (no via process is involved in the fabrication), forming the two-strip monopole. The bandwidth of the dual-frequency planar antenna is enhanced by taking advantage of the two-strip config- uration and the mutual coupling between the planar monopole and the two-strip monopole. The dual-frequency planar antenna achieves a bandwidth of 35% at the 2-GHz band (1.6–2.3 GHz) and 15% at the 5-GHz band (5.0–5.9 GHz) with an antenna height of 7–8 mm, which may find applications in mobile/wireless communication devices. A theoretical analysis and verifying exper- imental results are presented. Index Terms—Broadband antenna, dual-frequency antenna, low-profile antenna, monopole, two-strip, wireless applications. I. INTRODUCTION FOR applications concerning portable wireless communica-tion devices, such as mobile phone handsets or notebook computers, antennas with low-profile planar structures are es- sential for low-cost manufacturing and high integrability with printed circuit boards (PCB). On the other hand, the requirement for a dual-frequency operation has become a common sense for accommodating multifunctional services, such as voice, video, and data transmissions [e.g., for voice-over IP (VoIP) cellular phones]. To cover the DCS-1800 (DCS 1710–1880 MHz), PHS- 1900 (1895–1918 MHz), PCS-1900 (1850–1990