A Frequency-Reconfigurable Antenna Architecture Using Dielectric Fluids

A new frequency-reconfigurable antenna architecture is presented, in which a dielectric fluid is pumped into a cavity behind the antenna to change its resonant frequency. The continuous tuning provided by the changing fluid volume allows the resonant frequency to be adjusted to any value within the tunable range. This tuning method does not affect the power handling capability of the antenna and does not consume power while the resonant frequency is kept constant. This method of tuning also stands out in its class by offering a wide tuning range, high efficiency, and very good electrical isolation between the antenna and the control circuitry. The antenna was designed and optimized using Ansys HFSS software and several prototypes were built and tested. Measured results of the input response, radiation pattern, and efficiency are presented. Castor oil (ε_r = 2.7) and ethyl acetate (ε_r = 6) were used in physical tests as the tuning fluids to verify the simulated results. Good agreement between simulated and measured results was observed which is also in line with the behavior suggested by theory and earlier investigations.