A dual band back coupled meanderline antenna for wireless LAN applications

We present a novel dual band printed meander line antenna with a shaped ground plane and a back coupled rectangular patch. The aim was to achieve 2 GHz and 5 GHz covering the two main frequency bands of commercially available WLANs. To obtain a dual band with wide bandwidth operation, a meander line microstrip printed antenna with a matched feed and a shaped ground plane was first designed at 2.45 GHz. Then, a rectangular patch was added at the back of the meandered antenna substrate, with a small gap between the rectangular patch and the shaped ground plane. Changing the length of the rectangular patch allows the resonance frequency to be tuned, for instance 5.25 GHz. In fact, the resonance frequency can be continuously adjusted between 5.2 GHz and 7 GHz by changing the rectangular patch length. Furthermore, the tuning of the second resonance frequency has very little effect on the first one. The obtained bandwidth is 11% at 2.45 GHz and 6% at the second frequency for a return loss less than -10 dB. Consequently, this antenna offers sufficient flexibility for all types of wireless local area networks in the available frequency bands. This small antenna structure (31×8×1.6 mm³) and its achievable low price with an SMA type connector, make it appropriate for Notebook, PC, PDA and other commercial WLAN communications applications.