Microwave Power Transmission Research Articles

A Novel 10-Watt-Level High-Power Microwave Rectifier with an Inverse Class-F Harmonic Network for Microwave Power Transmission

A novel 10-Watt-Level high-power microwave rectifier with an inverse Class-F harmonic network for microwave power transmission (MPT) is presented in this paper. The high-power microwave rectifier circuit comprises four sub-rectifier circuits, a 1 × 4 power divider, and a parallel-series dc synthesis network. The simple inverse Class-F harmonic control network serves dual roles: harmonic control and impedance matching. The 1 × 4 power divider increases the RF input power fourfold, reaching 40 dBm (10 W). The parallel-series dc synthesis network enhances the resistance to load variation. The high-power rectifier circuit is simulated, fabricated, and measured. The measurement results demonstrate that the rectifier circuit can reach a maximum RF input power of 10 W at 2.45 GHz, with a maximum rectifier efficiency of 61.1% and an output dc voltage of 23.9 V, which has a large application potential in MPT.

Metasurface Antenna Designed for Quasi-Nondiffraction Beam Size Adjustment and Microwave Power Transmission

Metasurface Antenna Designed for Quasi-Nondiffraction Beam Size Adjustment and Microwave Power Transmission

Design of high‐efficiency rectenna for microwave power wireless transmission systems

Design of high‐efficiency rectenna for microwave power wireless transmission systems

Design of Series-Fed Circularly Polarized Beam-Tilted Antenna for Microwave Power Transmission in UAV Application

In response to the increasing deployment of unmanned aerial vehicles (UAVs) across various sectors, the demand for efficient microwave power transmission (MPT) systems for UAVs has become paramount. This study introduces series-fed circularly polarized (CP) and passively beam-tilted patch array antennas designed to enhance MPT in UAV applications, with the intention of addressing the needs related to extending flight times and improving operational efficiency. The radiating element of the proposed antennas employs the conventional model of the patch with truncated corners for CP operation, with transmission line lengths optimized for beam tilt to ensure precise energy transfer. Additionally, an open stub is integrated into the broadside series-fed antenna to improve impedance matching, which is crucial for maintaining signal integrity. The proposed design achieves right-hand circular polarization (RHCP) with an axial ratio (AR) below 3 dB across the operating band, indicative of its effectiveness in diverse UAV operational contexts. Prototypes of each proposed antenna were fabricated and measured according to the beam tilting angle. The measured RHCP realized gains of the proposed antennas are 14.59, 13.09, 13.07, and 10.71 dBic at the tilted angles of 0°, 15°, 30°, and 45°, respectively, at 5.84 GHz.

Robust and Optimal Feed Excitation Design of Transmitting Arrays for Microwave Power Transmission

Robust and Optimal Feed Excitation Design of Transmitting Arrays for Microwave Power Transmission

Microwave Power Transmission Using a Signal-to-Leakage-and-Noise Ratio to Protect Wireless Communication Devices

Microwave Power Transmission Using a Signal-to-Leakage-and-Noise Ratio to Protect Wireless Communication Devices

Multi-feed high-gain Huygens’ metasurface for microwave power transmission

We propose a multi-feed Huygens’ metasurface (HMS) transmitarray designed for microwave power transmission applications. A near-field distributed optimization mechanism is employed to determine the optimal focal lengths of subarrays. We aim to balance between illumination efficiency and interference from incident waves, leveraging the conjugate field matching method for precise phase compensation. This approach ensures robust radiation performance, notably reducing the focus-to-diameter ratio for large-aperture antenna arrays. Consequently, it mitigates spatial dispersion effects and upholds the operational bandwidth of mega antennas. As a proof of concept, we have designed a single-layer HMS transmitarray measuring 1.14 × 1.14 m2 (22 λ at 5.8 GHz). Through simulation, we have attained a peak gain of 35.47 dB and an aperture efficiency of 57.73%. Our design exhibits outstanding radiation performance, combined with advantages, such as a low profile, cost-effectiveness, and scalability.

A Novel Subarray Partitioning Algorithm for Small Sparse Transmitting Arrays in Microwave Power Transmission

A Novel Subarray Partitioning Algorithm for Small Sparse Transmitting Arrays in Microwave Power Transmission

Multi-Posture Microwave Power Transmission with Dual Alignment of Transmitting and Receiving Beams by Forward and Backward Time Reversal

Multi-Posture Microwave Power Transmission with Dual Alignment of Transmitting and Receiving Beams by Forward and Backward Time Reversal

Flat-top metasurface broadband mushroom antenna for microwave power transmission

Flat-top metasurface broadband mushroom antenna for microwave power transmission

Design and implementation of a near-field focused metasurface for microwave power transmission

In this paper, a near-field focused (NFF) metasurface composed of sub-wavelength structures for microwave power transmission is designed and implemented. Through full-wave simulations, a phase-shifting unit is proposed, which covers a transmission phase range of 360°, maintains a transmission amplitude better than −1.5 dB in most regions. Accurate design of the units at different positions in the array is achieved using phase compensation theory, forming the near-field focusing metasurface. By adjusting the transmission phase of the central unit in the metasurface to 30°, higher transmission efficiency can be achieved. Simulation results indicate that the designed near-field focused metasurface has the properties of high transmission efficiency, polarization insensitivity and distance insensitivity. To verify the transmission performance of the near-field focusing metasurface, a near-field focusing experimental platform is built and the microwave power transmission efficiency is calculated. Experimental results demonstrate that the proposed metasurface enhances the power received at the receiver, increasing the transmission efficiency by 433 %. The proposed near-field focusing metasurface holds potential for applications in high-power wireless power transfer and microwave intracavity focusing.

Non-Diffraction Self-Acceleration Beams With Customized Transverse Intensity Profiles Based on 3-D-Printed Meta-Structure

In this article, two 3-D-printed all-dielectric meta-structures that can produce diffraction-free self-acceleration beams with different transverse intensity profiles are proposed in the microwave frequency band. The first single-layer meta-structure, combining the Fourier lens phase and cubic phase distributions, is engineered to generate Airy beams with highly asymmetric transverse intensity profiles. In order to flexibly customize the propagation trajectory and transverse spot shape, Bessel-like beams with symmetric transverse profiles along arbitrary trajectories are realized by the second compact meta-structure based on phase synthesis. Calculating the phase mask of the metasurface is the most critical part. In this work, phase-modulated meta-structures can map the phase information to height distribution of the cube elements that can be precisely controlled. To verify the validity, two prototypes are printed and measured. From the beam intensities at different cross sections along the propagation trajectory, the oscillating multilobe intensity pattern of the 2-D Airy beam and the symmetric non-spreading central main lobe of the Bessel-like beam can be observed in simulation and measurement. Besides that, two kinds of beams have transverse acceleration behavior and self-reconstruction property. Therefore, the proposed meta-structures have great potential in numerous challenging fields, like microwave power transmission, secure communication, imaging, and detection.

Curved-Retrodirective Beamforming System to Improve Microwave Power Transmission Efficiency in the Fresnel Region

This paper presents a curved-retrodirective beamforming system for improving microwave power transmission efficiency in the Fresnel region. Since microwave power transmission in the far-field region has very low efficiency, studies on the Fresnel region are being actively conducted. In these studies, a retrodirective beamforming (RDB) technique is popular. The RDB system with a sub-array structure was a realistic structure that reduced system complexity. However, the transmission efficiency is lowered because the beamwidth of the transmitter antenna element is narrow. To solve this problem, this paper proposes a curved-retrodirective beamforming system that can focus the microwave power on the receiver. The proposed system uses the peak gain of the transmitter antenna element by using tilted beams to improve transmission efficiency. The system design method that can maximize the transmission efficiency is also presented depending on the given conditions such as transmission distance, characteristics of the transmitter and receiver antenna. The simulation showed a reduction in power leakage compared to the conventional system. The fabrication and measurement validated the efficiency improvement of the proposed system for IoT devices in the Fresnel region.

First Demonstration of Watt-Level C-Band MMIC Rectifier With GaN Schottky Diode

In this letter, a watt-level C-band monolithic microwave integrated circuits (MMICs) rectifier with lateral gallium nitride (GaN) Schottky barrier diode (SBD) is demonstrated for the first time. The proposed MMIC is fabricated on SiC-based AlGaN/GaN heterojunction material with a circuit dimension of only 2.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 2.1 mm. Benefited from the high-performance GaN device and the well-designed circuit, high conversion efficiency of 51.4% is achieved at an input power of 30.3 dBm, a frequency of 5.5 GHz, and a load resistance of 120 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $</tex-math> </inline-formula> , significantly outperforming previously reported MMIC rectifier and showing its great potential for high-power and high-efficiency microwave power transmission (MPT).

Compact high‐efficiency c‐band rectifier with high input power for microwave power transmission

AbstractThis letter presents a novel C‐band rectifier that is capable of handling high input power. The rectifier consists of a Schottky diode, an impedance matching circuit with a compensation microstrip structure, and an output filter with harmonic suppression and ripple smoothing. The experimental results indicate that the rectifier yields a conversion efficiency exceeding 70% and a peak efficiency of 74.1% over a wide input power range of 20 to 26 dBm (6 dB) at 5.8 GHz, utilizing a single Si‐based Schottky diode. Furthermore, the rectifier has a compact size of 28 mm × 15 mm. Given its cost‐effectiveness and outstanding performance, this rectifier presents an attractive option for large‐scale microwave power applications.

Dependence of the Inverse Spin Hall Voltage in Py/Ta Microstrip Array on the Microstrip Width

Since inverse spin Hall effect (ISHE) can transform microwave energy into direct current (DC) energy in ferromagnetic (FM)/nonmagnetic (NM) bilayer metal materials, the ISHE-based FM/NM microstrip arrays have clear potential to be used for microwave power transmission and harvesting. Driven by the need for the miniaturization of electronic devices, it is essential to study the dependence of the characteristics of FM/NM microstrip arrays on their geometries. In this work, we have experimentally demonstrated that the Py/Ta microstrip array’s ISHE signal increases linearly with an increase in the Py/Ta microstrip width and that the effective saturation magnetization of the Py film shows the same change tendency. Moreover, the anisotropy field of the Py film increases linearly as the width decreases. Our work provides a valuable reference for the future miniaturization of ISHE-based rectifier devices.

Near-field focused planar transmitarray with low profile design for microwave power transmission

This paper proposes a near-field focused (NFF) planar transmitarray with low profile operating in the C-band. A frequency selective surface (FSS) unit cell with a profile of only 0.15λ is designed by combining generalised scattering theory with full-wave simulations. To achieve better focusing, the transmission phase of the central unit cell of the transmitarray is adjusted to 90°. The focusing relative bandwidth is 13.7% at a centre frequency of 5.8GHz, which enables a good focusing effect to be achieved. Meanwhile, this paper evaluates the microwave power received at the receiver when the proposed transmitarray used in MPT system. The measured results show that loading the proposed transmitarray can improve the received power up to 510%. Futhermore, in the range of 220-660mm from the transmitarray, the received power can be increased to more than 300%.

Analysis and Measurement of Large Circular Transmitting Arrays for Microwave Power Transmission

Phased arrays have been widely used in microwave power transmission. The efficiency of rectenna is closely related to the received power density. Therefore, it is necessary to accurately analyze the radiation performance of the transmitting array in order to achieve the high-efficiency power transmission. And in order to meet the long-distance and high-efficiency power transmission requirements, the transmitting array needs to have the characteristics of large electricity sizes. The direct numerical analysis method of entire array will bring huge cost in computing time and storage space. Subarray extrapolation is a method to reasonably account for the edge effects of arrays, but only for rectangular arrays. Aiming at the geometric characteristics of the array contour, this communication proposes an irregular contour recognition method. This method can expand the application of subarray extrapolation method and realizes the purpose of accurately evaluating the radiation performance of large array antennas at small calculation cost. Finally, using a large transmitting array as an example, the proposed method is verified by comparing the results of subarray extrapolation, commercial software of entire array, and the experimental measurement to validate the correctness and advancement.

A Single-Layer Circularly Polarized Reflectarray Antenna with High Aperture Efficiency for Microwave Power Transmission

In this article, a single-layer circularly polarized reflectarray antenna (RA) with a linearly polarized feed is proposed for microwave power transmission. The unit cell of the reflectarray is composed of a rectangular patch surrounded by four groups of E-shaped structures, which feature a very low level of cross-polarization. Simulation results demonstrate that the phase of its reflection coefficient can be tuned continuously in a range of 500° by adjusting the lengths of the E-shaped structures. In response to a normally incident plane wave, the phase values of the reflection coefficient associated with two orthogonal linear polarization directions of the reflected wave can be tuned independently, which makes it possible to convert a linearly polarized incident wave to a circularly polarized beam. A reflectarray with 15 × 15 unit cells is fabricated and tested. The measurement results demonstrate a 3-dB axial ratio bandwidth of more than 2 GHz around the center frequency of 5.8 GHz. The measured gain value of the fabricated reflectarray is 25.4 dBi, corresponding to an aperture efficiency of 52.5%.

A Novel Synthesis Method of a Sparse Rectangular Planar Receiving Array for Microwave Power Transmission

A Novel Synthesis Method of a Sparse Rectangular Planar Receiving Array for Microwave Power Transmission