Frequency-Tunable Microstrip Antenna With Liquid Actuator Using Gradually Widened Transmission Line

This letter reports on a mechanically reconfigurable frequency-tunable microstrip antenna that uses a liquid actuator as the dielectric layer to reduce the antenna size compared to the wavelength. By using direct polymer vacuum deposition on a liquid, the dielectric liquid can be encapsulated inside the polymer to form an actuator, which can change the liquid thickness. When the actuator is situated within the antenna, its resonant frequency can be changed by changing the liquid thickness. The liquid, which has higher permittivity than air, can decrease the antenna size. The resonant frequency of the fabricated antenna can be changed from 23.53 to 23.28 GHz via 37.6 μm of deformation.