Zhen Yue

This letter proposes a simple ultrawideband rectifier operable up to the Ku band for wireless power transfer (WPT). A feedback line is introduced in the traditional voltage-doubling structure, which enhances second-harmonic recycling and high-frequency (HF) impedance matching, leading to a significant expansion of rectifier bandwidth. In addition, the combination of filtering capacitors and radial stubs forms an efficient dc filtering network, further extending the operating bandwidth. To validate the design, an ultrawideband rectifier is fabricated and measured. Measurement results show that the power conversion efficiency (PCE) exceeds 50% from 0.03 to 16.5 GHz. The peak PCE reaches 70.71% at an input frequency of 5.8 GHz, an input power of 24 dBm, and a $200~\Omega $ dc load. Compared to existing ultrawideband rectifiers, the proposed design demonstrates superior bandwidth performance and great potential for WPT applications.

This letter proposes a self-diplexing shared-aperture (SA) omnidirectional rectenna for simultaneous wireless information and power transfer (SWIPT). Unlike the traditional frequency splitting (FS) methods, this approach reuses the same antenna aperture to achieve omnidirectional reception and separation of power and communication signals at different frequencies, thereby enhancing system integration and environmental adaptability. The antenna is designed using characteristic mode analysis (CMA), with a monopole mode at low-frequency (LF) and a quasi-monopole mode excited by an equal-amplitude in-phase feeding network at high-frequency (HF), achieving omnidirectional radiation with vertical polarization (VP) at both bands. Additionally, a low-power rectifier is designed and verified, and a practical SWIPT system is constructed for testing, where the HF signal is used for communication and the LF signal for RF energy harvesting (REH). The results demonstrate that the designed rectenna and architecture are suitable for SWIPT applications.

This paper proposes an efficient and wide dynamic range rectifier based on power reflection structure. The rectifier consists of a branch-line coupler and two sub-rectifiers operating at different input power levels. The branch-line coupler is used as power reflection structure. Due to the electromagnetic symmetry of the branch-line coupler and the non-linear characteristics of the rectifier, the power reflection structure can reflect mismatched energy caused by load variations or input power fluctuations back into the sub-rectifier, which can improve the reflection coefficient of the rectifier. For validation in different application scenarios, two rectifiers operating at 5.8 GHz were designed, fabricated, and characterized. For the proposed rectifier I (with load resistances RL1 = 750Ω and RL2 = 300Ω), the measured PCE maintains exceeding 50% when the input power ranges from 8 to 29.2 dBm, and the peak PCE is 68.01% at 18 dBm input power. While for rectifier II (with load resistances RL3 = 800Ω and RL4 = 300Ω), the measured PCE remains over 50% with input power from −1.2 to 28.8 dBm, and the peak PCE is 68.51% at 15 dBm input power. Theoretical analysis and performance comparison are carried out that excellent performance of proposed rectifiers in extending the input power range, which can widely apply in WPT system.

This article introduces a nonharmonic dual-band receiver architecture based on signal reflection for simultaneous wireless information and power transfer (SWIPT) systems. The architecture includes a dual-band 3 dB hybrid coupler (operating at $\omega _{1}$ , $\omega _{2}$ ), rectifiers ( $\omega _{1}$ ), and information processing devices ( $\omega _{2}$ ). Leveraging the property that radio frequency (RF) signals are transmitted in the passband and reflected in the stopband, along with the coupler’s port reciprocity, RF power and information signals at different frequencies can be output between the through/coupled and isolation ports with high isolation. This arrangement can effectively reduce the interference of high-power RF energy on information signals while maximizing the utilization of RF energy improving the overall system efficiency. To validate the proposed architecture, a dual-frequency SWIPT receiver operating at 2.45 and 5.8 GHz was designed and fabricated. The simulations and experimental validations confirm that the proposed receiver can achieve 80.4% power conversion efficiency (PCE) with 25 dBm input power, and the isolation between the power and information signals reaches up to 55 dB. The receiver can achieve efficient energy conversion with minimal interference to the information signal. Additionally, we further discuss the feasibility of the signal reflection-based SWIPT receiver architecture for broadband information signal processing, expanding the practical application value of the receiver in SWIPT systems.

The quantity and variety of small electronic devices in the Internet of Things (IoT) are steadily increasing, leading to an urgent demand for wireless power supply methods for moving and multiple targets. This article proposes a novel tracking wireless power transfer (WPT) system for moving and multiple targets based on retrodirective array. The system includes a retrodirective power supply subsystem and power receiving targets. The principle of retrodirective system with different frequencies and its performance for multiple targets are analyzed and simulated. Real-time adaptive tracking of moving and multiple targets is achieved by beamforming according to beacon signals. Utilizing different frequencies and polarization enhances isolation between transmitting and receiving, enabling high-power and far-field WPT. A prototype of the proposed system is fabricated and measured. A single power-receiving target can receive a maximum of 24 dBm of 5.8 GHz microwave power at a distance of 5 m. After rectification, it can drive a temperature and humidity sensor and a communication module, allowing for environmental sensing and information feedback. The system can maintain continuous operation of the target while it moves within a wide 3D range of ±60∘. Additionally, continuous power supply with independent tracking for two targets is also achieved, verifying the tracking functionality for multiple targets.

This paper presents a high-efficiency and integrated millimeter-wave rectenna, which aims to provide stable wireless power supply for small wireless sensor networks in Internet of Things (IoT) environments. The antenna adopts slot-coupled feeding, with the feed line and the radiating patch located on opposite sides of the ground plane, it can effectively reduce the interference between the antenna and circuitry and increase the effective radiating area. Two Schottky diode are symmetric parallel mounted in rectifier, which can reduce the power losses caused by the junction resistance, and improve the power conversion efficiency (PCE). The measurement results show that the rectenna has achieved a maximum gain of 19.2 dBi, and PCE of 66.1% with 188 Ω load at 21 dBm input power. Additionally, by using the tiled stacking technique, a DC-DC power management module, a Bluetooth transmitting module and temperature, humidity, and light sensors were integrated with the rectenna to construct a highly integrated millimeter-wave power receiver with dimensions of only 32×32×10 mm ³ . This receiver can stably receive RF power from external wireless power source and drive the sensors and information transmitter module to return data in real-time, achieving simultaneous wireless power and information transfer (SWIPT), which demonstrate significant application potential in IoT scenarios.

With the emergence of the Internet of Things (IoT), the demand on the wireless power supply to consumer electronics simultaneously requires much more location freedom, ease of use, and performance with wireless communications. In this paper, an unenclosed quasi-static cavity resonator (QSCR) constructed with metallic strips and the design method are proposed and theoretically analyzed. This unenclosed QSCR has a simple structure, which benefits the wireless charging for portable/wearable electronics and smart appliances in the office and home environment. Meanwhile, it can achieve simultaneous ubiquitous 3-dimensional (3-D) wireless power transfer (WPT) inside the cavity and through-wall wireless communications with external electronic devices. Simulation and experimentation are performed to verify the theoretical analysis of the proposed cavity resonator and the WPT system based on it. As demonstrated, at a powering frequency of 6.78 MHz, the unenclosed QSCR can wirelessly transfer power to the receivers with a maximum power transfer efficiency of 90.5%, and an efficiency exceeding 51.5% is obtained at almost any position within the cavity space. The measured through-wall wireless communication channel attenuation introduced by the unenclosed QSCR is below 2.87 dB. By adjusting the inserted lumped capacitor value, the system can work at any desired frequency.

This letter proposes an integrated rectifying-mixer (IRM) circuit designed for simultaneous wireless information and power transfer (SWIPT) receiver architecture. The advantage of IRM is that it combines the functions of rectifier and mixer. When used in the SWIPT receiver, it can process information and power simultaneously, greatly improving the integration of SWIPT receiver and communication anti-interference capabilities. To validate the design, the IRM is subject to both 5.8-GHz high-power RF signal and 5.68-GHz low-power local oscillator (LO) signal. The measurements show that the maximum power conversion efficiency (PCE) is 51.25% for quadrature phase shift keying (QPSK) (17-dBm RF input) signal, 47.99% for binary phase shift keying (BPSK) (17-dBm RF input) signal, 61.7% for continuous wave (CW) signal (21-dBm RF input), and the conversion loss (CL) is 18.2 dB. In addition, the communication function of IRM is validated by measuring the error vector magnitude (EVM), proving that the IRM circuit is suitable for SWIPT systems.

This letter describes efficient high-power rectifiers, using a cost-effective AlGaN/GaN Schottky barrier diode (SBD) with accurate extraction of large-signal parameters as the rectifying device. The thin-barrier (TB) recess-free GaN SBD exhibits a low turn-on voltage of 0.5 V, a low on-resistance of 6.2 $~\Omega $ , a low junction capacitance of 0.28 pF, and a high breakdown voltage of 66 V. A precise large-signal equivalent-circuit model is derived by elaborating the measured $I$ – $V$ , $C$ – $V$ data, and $S$ -parameters under different dc bias conditions. For model verification, two separate rectifiers working at 5.8 and 10 GHz are fabricated. The measured results indicate that, with 31-dBm input power, the maximum efficiencies of the two rectifiers are 78.9% and 76.6% at 5.8 and 10 GHz, respectively. The maximum power handling capability of each single SBD reaches 36 dBm. Owing to the low-cost high-performance GaN SBD with an accurate model, the high-power rectifiers exhibit the merits of compact size and high efficiency, indicating great potential for large-scale microwave power transfer (MPT) applications, such as space solar power systems (SSPS).

This letter presents an efficient and compact ultrawideband (UWB) rectifier for wireless power transfer (WPT) and energy harvesting (EH) systems. The rectifier utilizes the voltage-doubling topology, which can effectively compress load impedance and facilitate broadband impedance matching. The input impedance matching network (IMN) is achieved using an L-type microstrip branch cascaded with a lumped inductor, which can counteract the capacitive of the diodes and reduce the circuit size. The proposed rectifier was designed and fabricated for verification with a 14.3 $\times$ 7.4 mm dimension. The measured results show that the rectifier can provide 197.6% (0.04–6.74 GHz) fractional bandwidth (FBW) with the power conversion efficiency (PCE) exceeding 50% and 196.8% (0.05–6.2 GHz) bandwidth with the PCE exceeding 60% at 22 dBm input power. The peak PCE reaches 74.8% at 1.9 GHz. Compared with traditional UWB rectifiers, the proposed one exhibits the merits of small size, high efficiency, and wider bandwidth.