This study deals with the inductive-based wireless power transfer (WPT) technology applied to power a deep implant with no fixed position. The usage of a large primary coil is here proposed in order to obtain a nearly uniform magnetic field inside the human body at intermediate frequencies (IFs). A simple configuration of the primary coil, derived by the Helmholtz theory, is proposed. Then, a detailed analysis is carried out to assess the compliance with electromagnetic field (EMF) safety standards. General guidelines on the design of primary and secondary coils are provided for powering or charging a deep implant of cylindrical shape with or without metal housing. Finally, three different WPT coil demonstrators have been fabricated and tested. The obtained results have demonstrated the validity of the proposed technology.