Study of electromagnetic wave excitation and propagation in underground continuous coal mining environments

It is important to be aware of the geological structures surrounding a coal mine tunnel, especially behind the cutting wall. Electromagnetic (EM) sensors such as ground penetrating radars have been used for this purpose. However, so far, most GPR systems used for this are on the ad-hoc basis and there is a lack of understanding of wave propagation phenomena in active continuous coal mining tunnels that are often very complex environments involving mining machinery, moving water and coals, ceiling stabilization structures, and different geological compositions in surrounding media. This paper presents findings of EM wave propagation properties in typical underground continuous coal mining tunnel scenarios based on simulation conducted using commercial HFSS software. Several concepts for launching EM waves in tunnel environments were explored and are discussed here. These concepts include water rod antenna, ceiling-bolt monopole and dipoles, and end-fired array.