Reconfigured slot-ring antenna for 2.4/5.2 GHz dual-band WLAN operations

A reconfigured slot-ring antenna fed by a coplanar waveguide (CPW) is proposed for the wireless local area network dual-band applications at 2.4 and 5.2 GHz bands. The slot-ring antenna together with its feeding structure has preserved a uniplanar configuration. The slot-ring is directly connected to a feeding CPW. The slot-ring's first and third resonant modes provide antenna's passband. The antenna's spurious modes are suppressed by adding to the slot-ring four metal strips at proper positions. An additional short-circuited CPW is stretched out from the end of the CPW feed, entering into the central circular patch of slot-ring to improve the impedance matching at 5.2 GHz frequency band. A pair of shunt slot tuning stubs, which are placed at the inner edge of the slot-ring, are used to tune the antenna's third resonant frequency to 5.2 GHz. This antenna has achieved fractional bandwidths of 7.5 and 10.4% at 2.4 and 5.2 GHz frequency bands, respectively. The return losses obtained are −30.56 dB at 2.4 GHz and −41.71 dB at 5.2 GHz. Details of the antenna designs and experimental results are presented and discussed.