Dual Band Rejected Low Profile Planar Monopole Antenna for UWB Application

In this paper, a new design of ultra-wideband band (UWB) antenna with dual band rejection characteristics and sizeminiaturization approach has been presented. The proposed antenna consists of unique patch of trapezoidal shape, 50 Ω impedance triple down step microstrip feed line (on top plane) and partial ground plane (on bottom plane). The patch tapering results to bandwidth (BW) improvement. It works efficiently over the impedance bandwidth of 3-13 GHz and gives Fractional Bandwidth (FBW) of 125% that covers the entire UWB band. It provides nearly omnidirectional radiation pattern, has good realized gain and impedance matching. A triple step feed increases electrical length of patch, which leads to antenna size miniaturization. Therefore, the proposed antenna has been designed with dimensions of 22 mm × 28 mm × 1.6 mm, dielectric constant (εr) of 4.4 and tangent loss of 0.02. For wireless applications, some specific UWB systems suffer from strong narrowband interference of unlicensed (ISM band) wireless communication devices. To avoid this unwanted interference, band rejection characteristics should be inserted into the antenna patch structure. The proposed antenna has designed with dualband rejection capability that efficiently avoids Wi-MAX and WLAN interference. The V-slot is etched on patch radiator to reject Wi-Max (3.15-4 GHz) and single C-strip pair besides feed line is used to reject WLAN (5.18-5.95 GHz) band. The output performance has measured in terms of simulated reflection coefficient and VSWR.