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

Abstract

This paper presents a compact wide-slot ultrawide-band (UWB) antenna with reconfigurable and sharpdual-band notches compatible with the underlay cognitive radio systems. The antenna slot and tuning stub are reshapedin such a way that the proposed antenna operating bandwidth extends along the frequency band specified for UWBapplications (3.1–10.6 GHz). In spite of their sharpness, the generated band notches perfectly cancel the interferencewith the entire 5 GHz wireless local area 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 notch is presented by attaching a pair ofquarter wavelength parasitic elements to the antenna ground plane, while the other band notch is produced by engravinganother pair of half wavelength parasitic elements within the antenna wide slot along the circumference of the antennatuning stub. The reconfiguration of the band notches is achieved by inserting a pair of PIN diodes for each pair ofparasitic elements. The simulated and measured results accentuate the UWB coverage of the proposed antenna, andalso verify the reconfigurability and the sharpness of the antenna band notches. Moreover, the antenna has a noticeablystable radiation pattern over the entire band of operation with omnidirectional pattern convenient for portable UWBgadgets.