ABSTRACT
This chapter discusses the field of inductive coupling for wireless power transfer. Although the principles of inductive power transfer are not new, the task of achieving a reliable yet efficient inductive link requires a detailed knowledge of the specific requirements for the application field and a deep understanding of the underlying physics. In order to illustrate the difference between the three field regions, as described above, the magnetic field of a small loop antenna is discussed. The radiation resistance of loop antennas with uniform current and dimensions small compared to the wavelength can be easily evaluated using the following expression. In general, for the electrically small loop antennas being investigated in this work, the loss resistance is generally much larger than the radiation resistance. The principles of inductive power transfer were presented both from a circuital and from an electromagnetic perspective.
