Banwidth Reconfigurable Filtering Antenna

A microstrip bandwidth reconfigurable filtering antenna is implemented by simply tuning the transmission zeroes. The proposed filtering antenna is developed by integrating the filter characteristics into the 50 Ω microstrip feed line of the antenna through two independent coupled resonators. The energy coupling between the transmission line and the planar loop resonator and dual F shaped resonator generates the transmission zeroes. These transmission zeroes at specified lower frequencies are generated in order to provide better selectivity over the edges of the pass band to promote high suppression of interferences. The varactor diodes are explicitly loaded at distinct locations in the resonators to achieve bandwidth reconfiguration. The two transmission zeros are tuned between 1.6–1.9 GHz and 2.1–2.42 GHz respectively by varying the capacitance of the two varactor diodes with percentage bandwidth of 17.1% and 14.1% respectively to support mobile and wireless short range applications. The proposed filtenna provides insertion loss less than 3 dB with good impedance matching below 15 dB.