Cognitive radio is a network technology that automatically identifies available channels within a wireless spectrum.
Here, a circular reconfigurable antenna is designed to address problems that occur when using a microstrip antenna in cognitiv
e radio systems. The reconfigurability is accomplished by repeated frequency, pattern and polarisation shifts. We are reconfiguri
ng this jobby adjusting the resonant frequency of the antenna.Use two parasitic metallic elements that are coplanners each other
. For reconfiguring the antenna within the UWB frequency band, three idle switches are used between the metallic strips. The re
configurability is observed in the frequency band of 3 GHz to 9 GHz. Results acquired along with radiation pattern and gain in t
erms of reflection coefficient
