Mie Resonances in Water Spheres for Microwave Metamaterials and Antennas

All-dielectric metamaterials rely on high-permittivity inclusions, which support Mie resonances. At microwave frequencies, distilled water exhibits a relatively high permittivity with tunable dynamic properties that are interesting for microwave devices, although absorption in water reduces their efficiency. In this paper, we investigate the scattering and absorption of single water spheres of various sizes and temperatures. The study is based on analytical calculations of Mie resonances. We also investigate the balanced electric/magnetic dipole excitation for more directive scattering in the forward direction. Finally, we discuss the major differences and similarities between water spheres and water cylinders. The results can be used as guidelines for metamaterial-based components as well as for dielectric resonator antenna designs.