Design of Tri-band Printed Monopole Antenna for Wlan and Wimax Applications

A novel printed monopole antenna with a pair of parasitic patches for wideband operation is proposed and studied. With the use of parasitic patches along the microstrip feed line, a good performance of bandwidth enhancement is obtained. The measured impedance bandwidth, defined by voltage standing wave ratio (VSWR) ≤ 2, can operate from 2.3 to 6.2GHz. A tri-band printed monopole antenna is created by introducing two notched bands in the wideband antenna. Etching an n-shaped slot on the radiating element and embedding a U-shaped parasitic strip on the bottom, two notched bands from 2.78 to 3.34GHz and from 3.78 to 5.1 GHz are achieved. The measured impedance bandwidths of the tri-band antenna are 410 MHz (2.37–2.78GHz), 440MHz (3.34– 3.78GHz) and 1000MHz (5.1–6.1 GHz), which can meet the bandwidth requirements of 2.4/5.2/5.8 GHz wireless local area network (WLAN) and 2.5/3.5/5.5 GHz worldwide interoperability for microwave access (WiMAX) standards. In addition, the proposed antennas have good omnidirectional radiation characteristics and stable gains over the whole operating bands.