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

Abstract

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.