A Polarization-Reconfigurable Water-Loaded Microstrip Antenna

A novel single-feed microstrip antenna with polarization agility is proposed. Loading the distilled water cylinder(s) at the four corners of the square patch with different heights, the effective permittivity of resonant mode is changed. By perturbing the heights of the four water cylinders, the circular polarization radiation with a wide 3-dB axial-ratio beamwidth can be obtained. In addition, the polarization reconfigurability with right-hand circular polarization, left-hand circular polarization, and linear polarization can be achieved by controlling the height of the water. To demonstrate the design concept, a prototype antenna was fabricated and measured. The simulated and measured results are in good agreement.