We propose a dual-band wireless power transfer (WPT) system employing a dual-mode inductor. The dual-mode inductor is possible through enforcing a self-resonance condition by loading an inductor in series by a tank circuit. In return, two distinct resonances are achieved, simultaneously, utilizing a single compensation capacitor as the inductance of the dual-mode inductor appears with a smaller value after its self-resonance. Also, by maintaining the same mutual coupling, the coupling coefficient becomes larger at the higher resonance, which allows for the employment of the same source/load admittance inversion network to achieve maximum power transfer at both of the operating frequency bands, concurrently. We verify the operation by fabricating a dual-band WPT system, which shows measured efficiencies of 70% and 69% at 90.3 MHz and 138.8 MHz, correspondingly. The size of the WPT system is $\boldsymbol {50} \boldsymbol {\times } \boldsymbol {50}$ mm $^{\boldsymbol {2}}$ and has a transfer distance of 40 mm.

Design and Implementation of Dual-Mode Inductors for Dual-Band Wireless Power Transfer Systems

This paper proposes a new dual band coupled resonators band pass filter that employs two C-shaped defected ground structures (DGSs) loaded with lumped capacitors for dual band wireless power transfer (DB-WPT) applications. The proposed resonators produce two independent frequency bands for dual band operations of the WPT system. When the two C-shaped DGS are coupled back-to-back, it transfers to a dual band pass filter leading to compact and efficient WPT system working at 0.3 GHz and 0.9 GHz. The system has been analyzed using the J-inverter method for verification. A compact prototype with a size of 20 mm × 20 mm is fabricated, tested, and measured. The fabricated prototype achieves coupling efficiencies of 99% and 91% at a transmission distance of 10 mm for both operating bands at 0.3 and 0.91 GHz, respectively. Good agreements between the equivalent circuit model (ECM) and the measurements have been achieved.

Novel and Compact Design of Capacitively Loaded C-shaped DGS Resonators for Dual Band Wireless Power Transfer (DB-WPT) Systems

Compact multi‐frequency system design for SWIPT applications

Dual E-shape Defected Ground Structure (DGS) resonator coupled back to back for medium range non-radiative Wireless Power Transfer (WPT) is presented in this paper. The proposed design is based around the concept of resonant inductive coupling for power transfer and consists of E-shaped defect etched in the ground plane of the substrate. The design incorporates capacitive loading for miniaturization and is supported by analytical design procedure. An equivalent parallel RLC resonant circuit in conjunction with coupled mode theory (CMT) and S-parameters aids in the understanding of the proposed WPT system. A prototype, on Rogers RO4350B substrate, has been developed to operate at 0.27 GHz frequency and takes a board size of $20 \times 20\text{mm}^{2}$. A very good agreement between the simulated and measured results demonstrate the effectiveness of the proposed technique. The achieved performance significantly improves the efficiency of the DGS based WPT systems reported so far.

A High Q Dual E-Shaped Defected Ground Structure for Wireless Power Transfer Applications

In this paper, a new miniaturized compact dual-band microstrip slot antenna is presented. To achieve the dual-band characteristics, two adjunct partial arc-shaped small slots are joined to two main circular slots embedded in the ground of the antenna structure. With a reduced size of 30 × 28.5 × 0.8 mm3, the proposed antenna presents a dual-band characteristic. The design is optimized using a High Frequency Structure Simulator (HFSS) followed by experimental verifications. An impedance bandwidth, for S11 ≤ 10 dB, that covers the 1.8 GHz and 2.4 GHz bands is accomplished, which makes the proposed antenna basically suitable for hand-held devices and medical applications. More applications such as digital communication system (DCS) 1.71–1.88 GHz, personal communication services (PCS) 1.85–1.99 GHz, Universal and mobile telecommunications system UMTS 1.92–2.17 GHz, Bluetooth 2.4–2.5 GHz, and Wi-Fi 2.4–2.454 GHz, Industrial Scientific and Medical radio frequency (RF) band ISM-2.4 GHz, Wireless Local Area Network (WLAN-2.4) are possible by simply changing one of the geometrical antenna dimensions. The antenna is characterized by stable radiation patterns as well.

https://www.mdpi.com/2079-9292/8/10/1123/pdf

A Compact Semi-Circular and Arc-Shaped Slot Antenna for Heterogeneous RF Front-Ends

This brief proposes a design methodology based on the admittance ( ${J}$ -) inverters for a dual-band wireless power transfer (WPT) system that employs two cascaded circulars defected ground structure (DGS) resonators with different capacitive loading to guarantee distinct resonances. A single microstrip line excites the two DGSs, and when two DGS resonators are coupled back to back, it transforms to a dual band pass filter leading to WPT at both bands. Each of the DGS resonators has independent coupling. Thus, the realized ${J}$ -Inverters are designed independently. Also, we employ a single stub for the matching. This stub appears with a different length according to the operating frequency; hence, an independent external coupling is achieved at both frequencies. A compact size of 30 mm ${\times } \,\, 15$ mm is fabricated achieving a WPT efficiency of more than 71% at a power transfer distance of 16 mm for both bands (0.3 and 0.7 GHz).

Redzuan Saad

Papers

Dual-Band Defected Ground Structures Wireless Power Transfer System With Independent External and Inter-Resonator Coupling