Gravity-Controlled Liquid Metal Antenna for 6G Flying Base Stations: A 3-D-Printed Solution to Address Tilting

The upper mid-band, or Frequency Range 3 (FR3) from 7 GHz to 24 GHz, is critical for new 6G cellular services. Autonomous aerial vehicles (AAVs), such as flying base stations, are essential to maintain connectivity in congested areas. However, these flying base stations face several challenges that range from hardware limitations to security concerns. This study presents a novel 3-D-printed, planar, aerodynamic, and lightweight liquid metal-based antenna designed to address the tilting and rotation of AAV base stations, which is crucial for urban air mobility connectivity. The liquid metal inside a spherical chamber, guided by 45° curved reflectors, flows freely due to gravity, maintaining a stable shape that ensures optimal radiation directed toward the ground. The proposed antenna is designed to operate at a center frequency of 14.8 GHz with an operating band ranging from 14.2 GHz to 15.8 GHz, covering the newly allocated 6G FR3 band (14.3 GHz to 15.35 GHz) and achieving a peak gain of 8.02 dBi. Its performance is simulated across various tilt angles and effectively addresses the requirement for robust connectivity in dynamic AAV scenarios.