A compact wide-slot UWB antenna with reconfigurable and sharp dual-band notches for underlay cognitive radio applications

Abstract

This paper presents acompact wide-slot ultrawide-band (UWB) antenna with reconfigurable and sharpdual-band notches compatible with the underlay cognitive radio systems. Theantenna slot and tuning stub are reshaped in such a way that the proposed antennaoperating bandwidth extends along the frequency band specified for UWBapplications (3.1-10.6 GHz). In spite of their sharpness, the generated bandnotches perfectly cancel the interference with the entire 5 GHz wireless localarea network (WLAN) frequency band (5.15-5.725 GHz) and that of the militaryX-band satellite communications downlink (7.25-7.745 GHz). The WLAN band notchis presented by attaching a pair of quarter wavelength parasitic elements to theantenna ground plane, while the other band notch is produced by engraving anotherpair of half wavelength parasitic elements within the antenna wide slot along thecircumference of the antenna tuning stub. The reconfiguration of the band notchesis achieved by inserting a pair of PIN diodes for each pair of parasiticelements. The simulated and measured results accentuate the UWB coverage of theproposed antenna, and also verify the reconfigurability and the sharpness of theantenna band notches. Moreover, the antenna has a noticeably stable radiationpattern over the entire band of operation with omnidirectional pattern convenientfor portable UWB gadgets.