Double Dipole Antenna for Dual-band Wlan Applications

A double dipole antenna design is proposed for wireless local area network (WLAN) applications. Two parallel dipoles are used to facilitate operation in both the standard WLAN frequency bands (IEEE 802.11b and IEEE 802.11a) simultaneously. The lower band dipole is rhombus shaped and radiates above a planar ground plane, while radiation from the rectangular higher band dipole is directed through the use of a passive director. The antenna is characterized in terms of impedance bandwidth, gain and radiation patterns through simulations and measurements. The design addresses the need for dualband operation, while delivering directional radiation patterns with adequate gain, low cross-polarization and a good front-to-back ratio. The 2.4/5 GHz WLAN bands are covered with an impedance bandwidth of 17.8% and 26.4% respectively, for a VSWR better than 2:1.