The propagation path loss of magnetic induction signals through soils and reinforced concrete for underground communication

This paper investigates path loss of magnetic induction (MI) signals for underground communication to quantify environmental impacts on signal attenuation. A COMSOL finite element model is built to simulate MI propagation in uniform soil and complex underground scenarios, verified by analytical solutions and field tests. Parametric simulations systematically explore how reinforced concrete rebar mesh (diameter and spacing) affects MI transmission: steel meshes raise path loss, which intensifies with larger rebar diameter and smaller spacing. We also analyze coil placement effects and confirm mesh-induced extra loss is decoupled from coil attitude loss. Finally, an empirical formula for mesh-attributed additional path loss is proposed, consistent with simulations. The results support the design of underground MI communication systems for disaster rescue positioning and structural health monitoring.