Combined wideband and narrowband antennas for Cognitive Radio applications

Cognitive radio (CR) is a new paradigm which aims to make more efficient use of the frequency spectrum whilst guarding against interference and generally providing a better quality of service for the user. In order to work alongside existing (so called legacy) users the CR must monitor the available frequency spectrum, and reconfigure to transmit on a different frequency when necessary. There are good technical arguments for using an ultra-wideband (UWB) antenna to perform the sensing function, whilst communicating via a narrowband antenna. This paper presents two different antennas which have been developed to address the specific demands of portable CR handsets. Each antenna combines UWB and narrowband functionality within a small space.