Electrically Small VHF MIMO Antenna For Underground Coal Mine Application

This work presents the implementation of an electrically small MIMO antenna configuration for underground coal mine applications. The proposed MIMO antenna configuration works at VHF band. The MIMO antenna configured using two electrically small antenna elements placed orthogonally relative to each other to achieve diversity performance. A study on MIMO input impedance and mutual coupling w.r.to inter-element spacing is performed. The proposed MIMO antenna exhibits good impedance matching less than −15
$\mathbf{dB}$
and inter-element isolation of more than 30
$\mathbf{dB}$
at the operating frequency. The diversity performance of the proposed MIMO investigated for realistic non-uniform (Gaussian/Uniform) indoor and outdoor propagation environments. The electromagnetic radiation safety limit for the human body from the proposed MIMO antenna is also verified using the human voxel model.