A Reconfigurable Filtering Antenna With Integrated Bandpass Filters for UWB/WLAN Applications

This communication presents a new reconfigurable filtering monopole antenna design with three switchable states for UWB/WLAN applications. The antenna has three independent ports for ultra-wideband state, 2.4 GHz WLAN narrowband state, and 5.8 GHz WLAN narrowband state, respectively. The narrowband state at 2.4 GHz is produced by a first-order microstrip filter using an open-loop resonator, and the narrowband state around 5.8 GHz is obtained by involving a third-order hairpin bandpass filter in the RF path. Frequency reconfiguration is achieved by RF path selection using dc controlled p-i-n diodes. As a result, narrowband filtering responses at desired frequency bands can be achieved. One antenna prototype is simulated, fabricated, and measured. Measured reflection coefficients and radiation patterns demonstrate that the proposed reconfigurable filtering antenna is an eligible candidate for future multifunctional systems incorporating both UWB and WLAN systems.