**Figure 12.**

*(a) Conformal split-ring loop self-resonator, (b) equivalent circuit [16].*

receiver. Under a perfect alignment, WPT offers a maximum measured transfer efficiency of 71.84%. This research uses the integration between the interdigital capacitor and the spiral coil to get a magnetic resonant resonator with high immunity for the misalignment instances. Wang *et al.* [16] proposed a conformal split-ring loop self-resonator which has a self-resonant frequency and its equivalent circuit is a series resonant circuit composed of an inductor-capacitor series connection as displayed in **Figure 12**. This resonator introduces a high transfer efficiency of 87.9% at a transfer distance of 22 mm. A resonant inductive link for

**Figure 13.** *Spiral coil integrated with lumped capacitor design (a) Transmitter's resonator, (b) Reciever's resonator [17].*

**131**

**Figure 14.**

**Figure 15.**

*Capacitive compensated plates design [18].*

*Planar view of the transmitter/Reciever [19].*

75% at a transmission distance of 38 mm.

**4. Strongly coupled magnetic resonance WPT**

*WPT, Recent Techniques for Improving System Efficiency DOI: http://dx.doi.org/10.5772/intechopen.96003*

powering pacemakers was presented in [17]. The transmitting resonator consists of two spirals printed on the top and bottom face of the Arlon substrate as illustrated in **Figure 13**. A surface-mounted capacitor is inserted in a shunt with the printed spiral to tune the resonance frequency at the desired value. On the other hand, the receiving resonator is a square split-ring resonator. Series–parallel capacitive plates are employed with a printed spiral resonator [18] to get satisfactory tolerance toward angular and lateral displacement. **Figure 14** shows capacitive compensated plates, C-shaped and mirrored L-shaped capacitive plates are formed on the top and bottom layer of the substrate. **Figure 15** presents an asymmetric resonant inductive coupled WPT system [19]. This system has a measured power transfer efficiency of

Strongly coupled magnetic resonance refers to inserting intermediate resonators with a high-quality factor (Q) in the transmission path between transmitter and receiver as revealed in **Figure 16**, these intermediate resonators are used to emphasize the transferred magnetic power. This technology is categorized as mid-range WPT. In 2007, a group of researchers at the Massachusetts Institute of Technology proposed

an experiment using a strongly coupled magnetic resonance technique [20].

*WPT, Recent Techniques for Improving System Efficiency DOI: http://dx.doi.org/10.5772/intechopen.96003*

*Wireless Power Transfer – Recent Development, Applications and New Perspectives*

receiver. Under a perfect alignment, WPT offers a maximum measured transfer efficiency of 71.84%. This research uses the integration between the interdigital capacitor and the spiral coil to get a magnetic resonant resonator with high immunity for the misalignment instances. Wang *et al.* [16] proposed a conformal split-ring loop self-resonator which has a self-resonant frequency and its equivalent circuit is a series resonant circuit composed of an inductor-capacitor series connection as displayed in **Figure 12**. This resonator introduces a high transfer efficiency of 87.9% at a transfer distance of 22 mm. A resonant inductive link for

*Spiral coil integrated with lumped capacitor design (a) Transmitter's resonator, (b) Reciever's resonator [17].*

*(a) Conformal split-ring loop self-resonator, (b) equivalent circuit [16].*

**130**

**Figure 13.**

**Figure 12.**

**Figure 14.** *Capacitive compensated plates design [18].*

**Figure 15.** *Planar view of the transmitter/Reciever [19].*

powering pacemakers was presented in [17]. The transmitting resonator consists of two spirals printed on the top and bottom face of the Arlon substrate as illustrated in **Figure 13**. A surface-mounted capacitor is inserted in a shunt with the printed spiral to tune the resonance frequency at the desired value. On the other hand, the receiving resonator is a square split-ring resonator. Series–parallel capacitive plates are employed with a printed spiral resonator [18] to get satisfactory tolerance toward angular and lateral displacement. **Figure 14** shows capacitive compensated plates, C-shaped and mirrored L-shaped capacitive plates are formed on the top and bottom layer of the substrate. **Figure 15** presents an asymmetric resonant inductive coupled WPT system [19]. This system has a measured power transfer efficiency of 75% at a transmission distance of 38 mm.
