An Integrated Ultra Wideband/Narrow Band Antenna in Uniplanar Configuration for Cognitive Radio Systems

A unique combination of wide and narrow band antenna, utilizing uniplanar nature of coplanar wave guide, for category-A cognitive radio systems is presented. It is demonstrated that, the space between two tapered slots, which forms an ultra-wideband configuration, (where the surface current concentration is relatively low) can be efficiently utilized to integrate a narrow-band antenna. The ultrawideband (UWB) and narrow band (NB) antenna provides a 2:1 VSWR bandwidth from 2.6 GHz to 11 GHz and 4.9 GHz to 6.2 GHz, respectively, with a reasonable isolation between them. The measured radiation pattern and gain are suitable for cognitive radio applications, where a wideband antenna is required for spectrum sensing and a narrow band antenna for operation. Moreover, the measured time domain characteristics demonstrate that, the antenna is also a potential candidate for medical imaging and weapon detection systems which are connected to the host through high speed WLAN.