A novel ferrofluids-based high-tuning high-Q variable solenoid inductor for frequency-reconfigurable circuits applications

In this paper, a high tuning-range variable solenoid inductor using ferrofluids-based core is proposed. The proposed micro fluidic-based wire-wounded inductor was fabricated and measured to prove the concept. The simulation results in HFSS and measurement results showed a successful inductance variation of the proposed inductor while its quality factor maintains sufficiently high for radio frequency applications. This novel technique allows any desired inductance variations to tune the radio-frequency circuits depending on the magnetic permeability of the applied ferrofluids. In addition to the magnetic permeability of the injected liquid which determines the inductance value and tuning range, its magnetic saturation value is a significant parameter for determining the corresponding quality factor and resonating frequency. The tuning range is measured for this work is 65% and 8.5 % respectively for EMG 901 and EMG 911.