EGaIn-Based Liquid Antennas: Beam Steering and Frequency Reconfiguration Using Microfluidic Control

This paper presents a dual-mode reconfigurable antenna platform based on liquid metal (EGaIn) microfluidic structures, targeting dynamic electromagnetic adaptation for future wireless systems. Two antenna configurations are explored: a $1 \times 3$ patch array for beam steering and a $1 \times 3$ dipole array for frequency agility. Beam steering is achieved by embedding phase-shifting segments within each feedline, where vertical EGaIn-filled pillars introduce discrete electrical delays. Radiation pattern redirection up to 30° is demonstrated while maintaining excellent impedance matching. In the second configuration, frequency reconfigurability is realized by tuning the effective dipole length through selective filling of liquid metal segments. Simulated results confirm smooth resonance shifts across a $2.4-3.8 \mathrm{GHz}$ range with negligible impact on radiation shape or matching performance. All models were designed and simulated using CST Microwave Studio with a fully automated Pythonbased workflow, enabling fast reconfiguration and repeatability. The results confirm that liquid antennas offer a low-complexity, low-cost solution for both spatial and spectral adaptability. This work paves the way for future compact fluidic architectures that unify beamforming and frequency tuning within a single design, offering strong potential for integration into reconfigurable intelligent surfaces (RIS), IoT platforms, and adaptive 6 G networks.