Frequency reconfigurable antenna using active capacitors

The development in wireless communication requires the use of tunable antenna adapted to the RF environment and providing optimal connectivity. In this paper, the design of frequency reconfigurable antenna is discussed. The reference square patch structure was optimized to operate at 2.45GHz. The frequency agility was achieved by integrating a varactor diode, a tuning range of 0.5-2.03GHz was realized. Then to improve the antenna performances, the varactor diode was replaced by a digital capacitor. A tuning range of 0.876 to 1.15 GHz was achieved with better radiation properties (impedance matching, gain...) due to the capacitor's ability to dynamically command the antenna using a binary code. Prototypes were realized for both cases. Simulated and measured results are presented and discussed.