A frequency re-configurable hexagonal shaped slot antenna for cognitive radio

An Antenna is proposed with its ground plane having a hexagonal shaped slot which is capable of switching the frequency to eight different bands, one at a time, between the frequency range of 2.3GHz and 3.8GHz. To achieve frequency re-configurability, the length of stub placed on top end of hexagonal slot is varied by use of four PIN diodes. Frequency tuning ratio of about 1.65:1 can be achieved using this design. Results such as return losses, gain, bandwidth and radiation patterns are presented in this paper. The advantage of the design is that it requires simple biasing circuit and no DC blocking capacitors are required.