Fig. 3From: High-permittivity ceramics enabled highly homogeneous zero-index metamaterials for high-directivity antennas and beyondSimulated optical properties of ZIM. a Photonic band structure of the ZIM for TM modes. b The effective refractive index and relative impedance of ZIM. c Electric field distribution over the cross section of the ZIM. d The radiation rate of the ZIM, featuring a maximum radiation rate of approximately 6.1 GHzBack to article page