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VLF Near-field of Radio Wave Penetrating Into A Ground Medium

In previous studies, the Sommerfeld Integrals (SIs) have been re-examined under the assumption of propagation parameter in air being approximated by γ0 ≈ iλ, in order to derive a few analytical formulas for near-field propagation at specific frequencies (typically below 100 kHz). Here, the resulting formulas are adopted over a plane conducting ground when a vertical magnetic dipole has been chosen as the exciting source for near-field propagation. Computations and discussions are carried out for field components and Poynting energy flow, respectively. Through the analysis, a simple and efficient solution is provided for one to investigate the wave propagation for application of deep underground explorations.