  Wireless communications in complex environments are constrained by lossy
media and complicated structures. Magnetic Induction (MI) has been proved to be
an efficient solution to extend the communication range. Due to the small coil
antenna's physical limitation, however, MI's communication range is still very
limited. To this end, Metamaterial-enhanced Magnetic Induction (M$^2$I)
communication has been proposed and the theoretical results suggest that it can
significantly increase the communication performance, namely, data rate and
communication range. Nevertheless, currently, the real implementation of M$^2$I
is still a challenge and there is no guideline on design and fabrication of
spherical metamaterial. In this paper, we propose a practical design by using a
spherical coil array to realize M$^2$I and we prove that it can achieve
negative permeability and there exists a resonance condition where the radiated
magnetic field can be significantly amplified. The radiation and communication
performance are evaluated and full-wave simulation in COMSOL Multiphysics is
conducted to validate the design objectives. By using the spherical coil
array-based M$^2$I, the communication range can be significantly extended,
exactly as we predicted in the theoretical model.
