Compact Stepped Monopole ACS-Fed Antenna for Tri-Band Applications

A compact planar triple-band stepped monopole antenna is presented. This asymmetric coplanar strip (ACS)-fed structure with single lateral ground plane is used to reduce the oversize of antenna, a single stepped monopole is designed to realize dual band frequencies operating, a Γ-shaped trip connecting the signal trip with the ground plane offers a more flexible and stronger coupling, an I-shaped stub inverted to the ground is employed to turn the impedance matching effectively, then a snake-shaped slot inserting on the ground plane is applied to launch a new frequency. The proposed antenna, with a very compact size of 21.65×12 mm², generates three desired resonant frequencies at about 2.4 (2.38-2.51), 3.5 (3.31- 3.58), 5.4 (5.14-5.65) GHz for WLAN and WiMAX applications. This antenna presents high bands isolation and good pass-band performance.