Frequency-polarization hybrid reconfigurable water patch antenna based on characteristic mode analysis

This paper presents a frequency-polarization hybrid reconfigurable water patch antenna using characteristic mode theory. Pure water serves as the radiator, with the electric-wall-like effect confining fields between the water and ground plane. Polarization reconfigurability (LP, LHCP, RHCP) is achieved by switching liquid filling to alter the perturbation structure, while frequency tuning is realized by adjusting the liquid area. Measured results show a 61.3% frequency tuning range (2.00–3.77 GHz). In the LP2 state, the 10-dB bandwidth is 7.5%, gain 3.0–4.7 dB, and efficiency 63.1%. In the LHCP state, the 3-dB AR bandwidth is 4.3%, minimum AR 0.9 dB, and efficiency 56.2%.