A Frequency- and Polarization-Reconfigurable Water Patch Antenna

In this letter, a frequency and polarization reconfigurable water patch antenna is presented. Frequency tuning is enabled by adjusting the size and height of the water-filled region in the radiating patch, as well as modifying the dimensions of the water-filled channels in the middle layer. Polarization reconfiguration is achieved by selectively injecting water into orthogonally arranged rectangular channels: injecting water into either the x-axis or y-axis channels enables circular polarization (CP), while simultaneous injection into both sets of channels results in linear polarization (LP). A reconfigurable prototype was fabricated and measured to evaluate the concept, demonstrating a tuning range of 1.51–2.69 GHz (56.2%) in the LP state and 1.73–2.55 GHz (38.3%) in the CP state, respectively. The measured peak gain reaches 7.2 dB for both LP and CP, with total efficiency exceeding 63% in both polarization states.