Wideband directive emission based on hyperbolic metamaterialsMina Ren, Yanhong Liu, Shengwang Yu, Lijuan Dong, Lixiang Liu, Fusheng Deng and Yunlong ShiEur. Phys. J. Plus, 134 6 (2019) 301DOI: https://doi.org/10.1140/epjp/i2019-12745-4