A Three-Dimensional Linear-to-Circular Polarization Converter Tailored by the Gravity Field

Abstract

In this paper, a three-dimensional (3D) linear-to-circular polarization converter (LCPC), innovatively tailored by the gravity field through the fluidity of liquid metal mercury (Hg), is designed and studied. The proposed LCPC is composed of a 3D glass cavity filled with Hg, a copper reflector, a trenched dielectric layer, and a copper patch. Due to the specially designed 3D glass cavity, Hg will flow in different parts of the glass cavity to form different resonant structures by means of rotation under the action of the gravity field. When the proposed LCPC is not rotated (is placed parallel to the xoy plane), the axial ratio band which is less than 3 dB (3-dB AR band) is obtained in the band of 32.42–42.82 GHz (the relative bandwidth is 27.64%). And when such a LCPC is rotated (is placed perpendicular to the xoy plane), the 3-dB AR band shifts to 18.88–32.86 GHz (the relative bandwidth is 54.04%). Besides, the surface current diagrams are investigated to explain the physics mechanism of the proposed LCPC, and relevant parameters are also discussed. In our design, the proposed LCPC has the advantages of wideband, tunable characteristics, and easy adjustment. In addition, it provides an innovative design idea of LCPC to promote potential applications of tunable devices.