Design of a broadband reconfigurable antenna for cognitive radio

In this paper, a broadband frequency/radiation patterns reconfigurable antenna is proposed for cognitive radio. The antenna consists of two branches, of which a transmission line and a dipole are integrated. Switches are used to connect branches to a feeding microstrip, and to tune the resonant frequencies of the antenna. Measurement and simulation results show that the proposed antenna offers multiple broadband, covering a frequency range from 2.41 GHz to about 6.88 GHz. Furthermore, by controlling the switches, current distribution on the transmission lines can be changed. This results in changing antenna radiation patterns. Thus, reconfigurability in radiation pattern can be also achieved.