5. Design approaches

Multi-coil [31, 32, 39–42] and single-coil [34, 43, 44] are two predominant strategies in designing dual-band near-field coupled resonators for WET links. Each


#### Table 3.

Comparisons of design approaches for dual-band near-field WET resonator.

Figure 3.

Summary of rectification techniques for dual-band near-field WET resonator.

#### Dual-Band Resonator Designs for Near-Field Wireless Energy Transfer Applications DOI: http://dx.doi.org/10.5772/intechopen.89218

design approach comes with their respective strengths and weaknesses which deserved appropriate assessment as tabulated in Table 3. Single-coil approach is preferred owing to minimum cross-coupling as compared to multi-coil [34]. Even though designing two separate coils in multi-coil approach necessitate more geometrical area, there is a greater potential in exploiting on highest possible transfer efficiency at two different frequencies in a single transmitter as it allows independent selection of inductance and quality factor [31].

Apart from deciding on the type of design approach to engage with, dual-band support configuration ought to be determined as well. Applicable configurations [28] involve designing either identical support mode as in dual-band transmitter (TX) and dual-band receiver (RX) or nonidentical support mode as in dual-band transmitter and single-band receivers. Bearing in mind that there is no superior design approach, rectification techniques employed address the respective shortcomings. Referring to Figure 3, rectification techniques for dual-band resonator designs which will be discussed in the following subsections encompass aspects relating to resonator design, resonator configuration, and impedance transformation network.
