Reconfigurable antenna structure for a wideband cognitive radio

In this paper the design of a single feed antenna that can be tuned to a frequency in the range 450 MHz to 2.2 GHz is discussed. A reconfigurable patch antenna structure is proposed and the frequency tuning is performed by switching in and out coplanar patches, switching in and out shorting posts and varying the voltage across a varactor diode. The quantity of interest in terms of tuning to a particular frequency is the input impedance or input reflection coefficient. The advantages and shortcomings associated with this structure as well as the possibility of implementing this structure with current and emerging enabling technologies is discussed.