Integrated wide-narrow band antenna for switched operation

Cognitive radio (CR) is a new paradigm which promises to yield an improved quality of service for the user whilst also enabling more intensive use of the available radio frequency spectrum. CR will require integrated wide-narrowband antennas for performing the search and communications functions. This paper helps to address this need by providing a new antenna which can be reconfigured between a narrow and ultra-wide impedance bandwidth. The final section of the paper demonstrates an ultra-wideband antenna having a variable lower cut-off frequency.