Ultra-compact CPW-fed Monopole Antenna with Double Inverted-L Strips for Dual-Band WLAN Applications

Wireless local area network (WLAN) is one of the rapidly growing applications in wireless communications. Antennas for portable WLAN devices require wideband, low profile, and compact design [1]. Dual-band antennas are also attractive because they eliminate the need of separate antennas by allowing operations at multiple frequency bands specified in IEEE standards 802.11b/g (2.400~2.484 GHz) and 802.11a (5.150~5.850 GHz) [2]. Coplanar waveguide (CPW)-fed antennas have been investigated for WLAN applications because of their advantages such as wide band characteristics, dualor multi-band operation, simple structures with only one metal layer, and easy integration on the circuit board along with integrated circuit components. However, CPW-fed antennas reported in the literatures so far exhibited insufficient bandwidth at 5 GHz band [3-4] or suffered from large size although they satisfied bandwidth requirements of WLAN [5-6]. In this paper, CPW-fed monopole antenna with double inverted-L strips was designed for dual-band WLAN applications. The fabricated antenna has an ultra-compact size (15 mm × 14 mm) that includes the size of ground planes. The measured characteristics exhibited wide bandwidths in both 2 and 5 GHz bands. Especially in 5 GHz band, the antenna demonstrated ultra-wide bandwidth covering from 4.76 to 6.48 GHz. Details of antenna design are described, and the simulated and measured antenna characteristics are compared and discussed.