ANALYSIS OF CPW-FED UWB ANTENNA FOR WIMAX AND WLAN BAND REJECTION

A compact ultra wide band (UWB) antenna with dual band notch characteristics is proposed. The antenna consists of a coplanar waveguide (CPW) fed bevelled rectangular patch and a modifled rectangular ground plane. A Z-shaped meander line parasitic element and a pair of symmetrical L-shaped quarter-wavelength stubs are employed to realise band-notched functions at WiMAX and WLAN bands respectively. By optimizing the dimensions and positions of these notch structures, the desired notch-bands of WLAN and WiMAX are achieved. Unlike other dual band-notched antennas reported in literature this antenna has a merit of regulating the centre frequency as well as the bandwidth of both the notched bands easily and independently. The measured i10dB S11 covers the bandwidth from 2.5 to 11.5GHz, with two notched bands from 3.3 to 3.6GHz and 5.2 to 5.75GHz. The proposed antenna exhibits nearly omni-directional radiation patterns with moderate gain and small group delay variations less than 0.5ns over the entire operating bandwidth except at the notched bands. Moreover, by using antenna transfer function, the time domain characteristic of the antenna is also studied to conflrm its suitability for UWB pulse communication.