This article presented a dual‐band monopole antenna fed by a coplanar waveguide (CPW) for wireless device applications in the 802.11b/a wireless local area network (WLAN) standards. The antenna consists of a rectangular radiator, two rectangular slots cut on both sides of the radiator, a semiring slot on the radiator, and a CPW feed for easy integration with other components on the printed circuit board. Parametric studies are carried out on the semiring slot and rectangular slots. The rectangular radiator generates two resonant bands at about 2.4 GHz for the 802.11b standard and 5.5 GHz for the upper band of the 802.11a. The semiring slot forms a resonator/bandstop filter to separate the radiator into two parts, hence generating another resonant band at around 5 GHz to cover the lower band of the 802.11a standard. The two rectangular slots improve impedance matching for the 802.11a standard. Simulation and measurement results of the proposed antenna show good agreements. Results show that the proposed dual‐band antenna has good performances in terms of radiation pattern, peak gain, and radiation efficiency. The bandwidth for the 802.11a standard can be easily adjusted using dimensions of the semiring and rectangular slot, giving an easy way for engineers to design antennas for wireless device applications for the WLAN standards. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1391–1396, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26859