Low-Frequency Wave Propagation in the Cave

Wireless communication within caves or tunnels has been researched for a long time. The major problem in cave communication is the limitation of wave propagation within the conductive cave wall, which makes it like the waves traveling in the waveguide. In addition, cave environments with curved and non-uniform paths that cause high attenuation differ from propagation in free space. However, the nature of the low frequencies, with their diffraction abilities and skin effects, allows them to communicate within caves. Therefore, this paper presents a study of low-frequency wave propagation in the cave by investigating the mechanism of low-frequency propagation within the cave. The method used was an experimental study by transmitting low-frequency waves through the cave cavity, which revealed the attenuation that occurred as the wave propagated in the cave. In conclusion, the significant factor is the skin depth generated by the electrical conductivity of the cave wall, which made it possible to explain the low-frequency propagation behavior in the cave and will use to develop a low-frequency propagation model.