A reconfigurable narrowband antenna integrated with wideband monopole for cognitive radio applications

A reconfigurable narrowband antenna integrated with a wideband monopole, suitable for cognitive radio applications, is proposed in this study. A set of matching circuits are designed to demonstrate that the structure can be tuned to wide range of frequencies in the narrowband mode of operation. The integrated structures have been manufactured and measured. The measured results agree well with the simulation results. Investigations show that the simulated total efficiency and realized gain is lower for lower frequency matching circuits, which agrees with the Chu-Harrington curve for electrically small antennas.