The printed monopole antennas are good candidates for the most radio-frequency systems, because of low cost, low profile and easy to integrate to MMIC. Recently, the dual-band and multi-band antennas have inspired high interest for communication systems. Wireless local area network (WLAN) technology is a wireless communication standard, which is operating range in the lower band of 2.4 to 2.484 GHz (IEEE 802.11b/g) and higher band of 5.15 to 5.825 GHz (IEEE 802.11a). In order to satisfy the WLAN standard, many monopole antennas have been proposed in the literature [1-9]. Such as CPW-fed tapered bent folded monopole antenna . Dual-band Hybrid Antenna is proposed for WLAN application . In [3-5], the microstrip-fed printed monopole antenna. In [6-9], dual-band antenna is proposed using a parasitic plate for WLAN applications. In this paper, we consider the lower-complexity and small antenna size for mobile devices. Compared to [6-9], our antenna can produce satisfactory results of antenna size, impedance bandwidth and simply geometric structure. And further, the dual-band characteristic of the monopole antenna is forming by using a parasitic plate under a rectangular patch. Details of the proposed antenna configuration and experimental results are discussed.