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+=====Overview of wireless power transfer=====
+====Overview====
+Wireless Power Transfer (WPT) can be implemented in many ways. The most well-known technologies in the sector today are depicted in Figure 1 and can be divided into WPT by acoustic or by electromagnetic means
+| {{:overview_wpt-technologies.png?600|}} |
+| Figure 1 overview of WPT |
+====Near-field versus far-field electromagnetic WPT====
+Near-field WPT is realised by a magnetic or electric field (IPT/CPT), whereas far-field WPT uses electromagnetic waves in the form of a radio frequency signal to transfer energy. Both techniques differ primarily in the distance between transmitter and receiver over which energy is transmitted. The range of near-field applications is typically limited to a few millimetres to a few centimetres, while far-field WPT extends from several metres to kilometres. Another key distinction is the alignment requirement between the transmitter and receiver. Near-field technology requires precise alignment, whereas far-field WPT does not. However, the most significant difference between the two methods lies in their efficiency.
+====Efficiency for Near-field applications====
+The efficiency of the WPT system depends on the type of technique. As seen in Figure 2, the implementation methods vary strongly in efficiency. Near-field electromagnetic WPT typically achieves a higher efficiency than far-field WPT. According to the distance, the energy transfer efficiency declines exponentially with all methods. This is due to the air gap and its poor conductive properties.
+The inductive coupling technology attains the highest energy transfer efficiency, varying from 70% up to 90%. In the same figure can be seen that the efficiency for magnetic resonant coupling strongly declines to a range of 40-60%. In the near-field technology this WPT method is used for greater distances, going from a few centimetres up to a maximum of 5m. A summary of these near-field methods is given in Figure 3.
+| {{:comparison_of_efficiency_for_different_wpt_techniques.png?500|}} |
+| Figure 2 efficiency of WPT (Jawad et al., 2017, p. 8) |
+| {{:near-field_technology_specifications.png?600|}} |
+| Figure 3 Near-field technology specifications (Jawad et al., 2017, p. 10) |
+----
+<color #808080>**References**</color>
+  * <color #808080>Detka, K., & Górecki, K. (2022). Wireless Power Transfer—A Review. Energies, 15(19). https://doi.org/10.3390/en15197236</color>
+  * <color #808080>Jawad, A. M., Nordin, R., Gharghan, S. K., Jawad, H. M., & Ismail, M. (2017). Opportunities and challenges for near-field wireless power transfer: A review. In Energies (Vol. 10, Issue 7). MDPI AG. https://doi.org/10.3390/en10071022</color>
+  * <color #808080>Minnaert, B. (2018). Near-Field Wireless Power Transfer for Non-Static Applications.</color>