Subsurface Electromagnetic Telecommunication - A Review

We present a review of the telecommunication possibilities for terminals that are buried in the earth or submerged in the sea. The important role of the operating frequency is stressed. Without being comprehensive, we discuss the relevance of the large number of theoretical papers on electromagnetic waves in conducting media. Our most important recommendation is that the highfrequency band be given more attention for telecommunication between terminals buried just beneath the air-ground interface. Also, we suggest that future research be directed towards the investigation of the frequency dependence of the conductivity and permittivity of geological materials.