Dual-band WLAN dipole antenna using an internal matching circuit

A dual-band dipole antenna for wireless local area network (WLAN) is designed and experimentally tested at both the 2.4 and 5 GHz (IEEE 802.11b/g and 802.11a) WLAN bands. The design procedure involves obtaining a full resonance frequency in the 2.4 GHz band and then using a matching network to achieve a secondary resonance at the 5 GHz band. It is shown that by correctly designing the dipole, the matching network can be simplified to only one series inductor. The design was experimentally verified by constructing a dipole on a FR4 board (12 mm * 45 mm * 0.45 mm) and measuring its input impedance and the radiation characteristics at both bands. The measured VSWR 2:1 bandwidth in the 2.4 GHz band is 710 MHz, and the bandwidth in 5 GHz band is wider than I GHz. The VSWR 3:1 bandwidth is more than 3.6 GHz and it covers from 2.32 GHz to above 6 GHz. It is significant that the designed dual-band dipole maintained good radiation efficiency values at both bands. Specifically, and based on the measured radiation patterns, an efficiency value of 85% similar to 87% is obtained at 2.4 GHz and a value in the range of 55 similar to 64 % is obtained in 5 GHz band.