A frequency reconfigurable circularly polarized microstrip patch antenna using liquid metal microswitches

Abstract

Reconfigurable antennas with adaptable frequency, pattern, and polarization offer flexibility and size reduction for wireless systems that must increasingly execute multiple missions with less volume. These antennas will also complement anticipated cognitive radio systems, which promise more efficient use of the electromagnetic spectrum. Microscale liquid metal switches are proposed to overcome the series loss, mechanical fatigue, and limited power handling reliability of common methods of antenna reconfiguration such as semiconductor diodes and microelectromechanical switches. The proposed microswitches consist of mercury droplets that selectively connect solid metal traces. Both fluidic and electrostatic switch actuation mechanisms are investigated, and an electrostatic switch is demonstrated. Electrostatically actuated switches are designed into a compact single-feed patch antenna configurable between two communication frequency bands and a GPS band with different circular polarizations. The antenna topology is based on a corner truncated square patch with switched sets of extensions to achieve resonant frequency and axial ratio control. Measurements of reconfigurable prototypes demonstrate frequency and polarization configurability in good agreement with full-wave simulations. The proposed reconfiguration mechanism is compared to other methods, and future directions for the integration of microfluidics in reconfigurable radio frequency systems are proposed.