A Passive 3-D Beam-Steering Gravitational Liquid Dielectric Resonator Antenna With Polarization Diversity

This article presents a passive 3-D beam-steering gravitational liquid dielectric resonator antenna (DRA) with polarization diversity. By utilizing the fluidity of the liquid induced by gravity and the symmetric configuration with specific feeding methods, the movable liquid part effectively functions as a 3-D director for both the slot and dielectric HEM113 modes. This enables wideband 3-D passive beam steering, even under conditions of random or unpredictable 3-D rotation of the antenna system. The theory and operation mechanism of 3-D beam steering is investigated from different perspectives, including the modal field analysis and the viewpoint of a short dielectric waveguide model. The antenna evolution from basic DRA to the proposed antenna is also introduced. Simultaneous 3-D beam steering and polarization diversity are achieved, which can greatly reduce the polarization mismatch due to the multipath effect for indoor applications and improve communication link stability. The proposed antenna exhibits a wide bandwidth, high stability, environmental shielding, and ease of installation without predetermining the installation angles. Its true passivity, without external drives or active components, ensures flexibility, compact size, and low cost. This work is useful for applications such as wall- or ceiling-mounted base stations.