A Varactor-Based Reconfigurable Filtenna

This letter details a new reconfiguration technique for implementing frequency-tunable bandpass filters. This is achieved by changing the filter total capacitance via an integrated varactor within its structure. The reconfigurable bandpass filter is then incorporated within the feeding line of a printed antenna to form one structure. This combination allows the tuning of the antenna operating frequency without incorporating active components and biasing lines on the antenna radiating surface. The integrated antenna-filter combination, with filtering ability while preserving the radiation performance, is referred to as a filtering antenna or a filtenna. A prototype for the reconfigurable filter and the reconfigurable filtenna are fabricated and tested. A good agreement is found between the simulated and the measured data.