Xin Duan

Bio: Xin Duan is an academic researcher from Sichuan University. The author has contributed to research in topics: Antenna (radio) & Metamaterial. The author has an hindex of 7, co-authored 14 publications receiving 121 citations.

A metamaterial electromagnetic energy rectifying surface with high harvesting efficiency

Abstract: A novel metamaterial rectifying surface (MRS) for electromagnetic energy capture and rectification with high harvesting efficiency is presented. It is fabricated on a three-layer printed circuit board, which comprises an array of periodic metamaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes. Perfect impedance matching is engineered at two interfaces, i.e. one between free space and the surface, and the other between the metamaterial particles and the rectifiers, which are connected through optimally positioned vias. Therefore, the incident electromagnetic power is captured with almost no reflection by the metamaterial particles, then channeled maximally to the rectifiers, and finally converted to direct current efficiently. Moreover, the rectifiers are behind the metal ground, avoiding the disturbance of high power incident electromagnetic waves. Such a MRS working at 2.45 GHz is designed, manufactured and measured, achieving a ha...

Wideband Metamaterial Electromagnetic Energy Harvester With High Capture Efficiency and Wide Incident Angle

Abstract: This letter presents a wideband metamaterial electromagnetic (EM) energy harvester with high capture efficiency and wide incident angle. It is an array of novel resonators comprising metallic mirrored split rings and hollow cylinders. The impedance of the harvester is engineered to match with free space, so that the incident EM energy is captured with minimum reflection, and then channeled maximally to the ports through optimally positioned vias. The hollow cylinder works equivalently as a shunt capacitance in series with an inductance to lower the resonator's quality factor, which significantly enhances the bandwidth. The power harvesting mechanism is analyzed using both the transmission line model and full-wave simulation. A metamaterial harvester of 10 × 10 unit cells is designed, manufactured, and measured, achieving a capture efficiency of up to 97.3% at 2.45 GHz. A wide relative bandwidth of 16% with efficiencies above 90% is observed from 2.3 to 2.7 GHz. Within a wide incident angle range (92° on E -plane and 44° on H -plane), the harvester manages to capture more than half of the incident energy.

A Microwave Power Transmission Experiment Based on the Near-Field Focused Transmitter

Abstract: For most microwave power transmission (MPT) applications, the microwave power is received within the near field of a large-scale transmitting antenna from a limited distance. This letter explores the design of a near-field focused transmitting antenna to concentrate the microwave power on the receiving antenna's aperture, and thereby to enhance the transmission efficiency of the MPT. A near-field planar array with a size of 1 m × 1 m working at 5.8 GHz is manufactured. To focus the microwave power at a distance of 10 m, its 8 × 8 radiation elements are fed with an equal amplitude but different phase using coaxial cables of different lengths. An MPT experiment is conducted. The measurement shows that, compared with a traditional equal-phase array, the near-field focused array obtains a much more concentrated microwave beam. The transmission efficiency is significantly increased from 32.98% to 41.85%.

Fabry–Pérot Resonator Antenna With High Aperture Efficiency Using a Double-Layer Nonuniform Superstrate

Abstract: Due to the nonuniform electromagnetic (EM) field amplitude distribution over its aperture, the Fabry–Perot resonator antenna (FPRA) suffers from relatively low aperture efficiency. In this communication, an FPRA with high aperture efficiency is proposed based on a double-layer nonuniform superstrate (DNS). The DNS is designed to have a constant reflection phase but a varying reflection magnitude, thereby obtaining a uniform EM field amplitude distribution over the FPRA’s aperture and, hence improving the directivity and the corresponding aperture efficiency. As an example, a cylindrical FPRA with an aperture diameter of $3.5~\lambda $ (where $\lambda $ is the wavelength in free space) is presented. In comparison with a uniform superstrate, the proposed DNS enhances the FPRA’s directivity from 19.6 to 20.4 dBi and correspondingly improves the aperture efficiency from 76.3% to 91.7%.

High Directivity Fabry–Perot Antenna With a Nonuniform Partially Reflective Surface and a Phase Correcting Structure

Abstract: In this communication, a superstrate for the high radiation performance of a Fabry–Perot antenna (FPA) is proposed that consists of a nonuniform partially reflective surface (NPRS) and a phase correcting structure (PCS). The NPRS and the PCS function to uniformize the amplitude and phase distributions, successively, of the FPA’s aperture field, thereby achieving a high directivity and a high aperture efficiency. Due to the independent amplitude and phase manipulations, the antenna design procedure is relatively rapid and effective. As a proof of concept, an FPA sample at an operating frequency of 5.8 GHz with a diameter of 200 mm is designed. The NPRS, comprising metallic square rings with dissimilar dimensions printed on a printed circuit board (PCB), is designed according to the leaky-wave method. A two-layer PCB structure is adopted as the PCS, which is designed by the transmission line model integrated with full-wave simulations. The FPA with the NPRS and the PCS is fabricated and measured for verification. The simulated and measured results are in good agreement. The directivity of the FPA with the proposed superstrate is 21.49 dB and the corresponding aperture efficiency is as high as 95.49% at 5.8 GHz.

Gain enhancement methods for printed circuit antennas

Abstract: Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.

Apparatus for transmitting electrical energy

Abstract: With a consumer and / or energy storage device, from the or the mobile moving body 3 moving on or roadway or rail is stopped, apparatus for inducing transmitting electrical energy, the roadway 1 comprising a floor derivative 5 which is attached, this floor derivative with a number of first induction coil 4 connected to the arranged and power along the roadway 1 or rail, the first induction coil towards the mobile 3 It has a magnetic conductive iron core 6 to generate a magnetic field oriented in. Inductive wheel 8 attached to the movable body 3 is magnetically conductive core 10 and the second induction coil 9 fixed with a magnetically conductive wheel disc 11 facing towards the linked roadway 1 or rails on both sides of the core , and a 12. To ensure low reluctance loss between and induction coil 4, 9 for contacting the road 1, the magnetic conductivity of the tire 13 is attached to the wheel disc by an elastic which is rotated by the movement of the object 3, the tire flat in the pressed state, to reliably bridge the gap remaining between the roadway and wheel disc. This device is advantageously used in conjunction with an electric vehicle in order to comfortably and quickly recharge the battery during or in parked cars.

Renewable energy harvesting and absorbing via multi-scale metamaterial systems for Internet of things

Abstract: Natural and human environments are abundant of unused renewable energy such as mechanical energy, acoustic energy, electromagnetic energy, thermal energy, etc. The idea of designing multi-scale metamaterials with super-normal functions on energy manipulation is utilized in multi-field renewable energy harvesting and absorbing. The metamaterials are able to enhance the local energy density by confining and focusing the energy before it to be harvested, leading to remarkable improvement of the output power and conversion efficiency. Leveraging the multi-scale metamaterials for renewable energy harvesting is an emerging direction to exploit the excess energy in the natural and man-made environments. This paper provides a brief overview of the studies published over the past decade on mechanical, acoustic, electromagnetic and thermal energy harvesting using the relevant metamaterials. The goal is to spark the interest of new investigators to this unconventional but fast-evolving branch of energy harvesting that will impact the Internet of things, smart cities and sustainable developments.

Low-Cost Nonuniform Metallic Lattice for Rectifying Aperture Near-Field of Electromagnetic Bandgap Resonator Antennas

Abstract: This article addresses a critical issue, which has been overlooked, in relation to the design of phase-correcting structures (PCSs) for electromagnetic bandgap (EBG) resonator antennas (ERAs). All the previously proposed PCSs for ERAs are made using either several expensive radio frequency (RF) dielectric laminates or thick and heavy dielectric materials, contributing to very high fabrication cost, posing an industrial impediment to the application of ERAs. This article presents a new industrial-friendly generation of PCS, in which dielectrics, known as the main cause of high manufacturing cost, are removed from the PCS configuration, introducing an all-metallic PCS (AMPCS). Unlike existing PCSs, a hybrid topology of fully metallic spatial phase shifters are developed for the AMPCS, resulting in an extremely lower prototyping cost as that of other state-of-the-art substrate-based PCSs. The APMCS was fabricated using laser technology and tested with an ERA to verify its predicted performance. The results show that the phase uniformity of the ERA aperture has been remarkably improved, resulting in 8.4 dB improvement in the peak gain of the antenna and improved sidelobe levels (SLLs). The antenna system including APMCS has a peak gain of 19.42 dB with a 1 dB gain bandwidth of around 6%.

Wideband Near-Field Correction of a Fabry–Perot Resonator Antenna

Abstract: A systematic approach to correcting electric near-field phase and magnitude over a wideband for Fabry–Perot resonator antennas (FPRAs) is presented. Unlike all other unit-cell-based near-field correction techniques for FPRAs, which merely focus on phase correction at a single frequency, this method delivers a compact near-field correcting structure (NFCS) with a wide operational bandwidth of 40%. In this novel approach, a time-average Poynting vector in conjunction with a phase gradient analysis is utilized to suggest the initial configuration of the NFCS for wideband performance. A simulation-driven optimization algorithm is then implemented to find the thickness of each correcting region, defined by the gradient analysis, to complete the NFCS design. According to the predicted and measured results, the phase and magnitude distributions of the electric near field have been greatly improved, resulting in a high aperture efficiency of 70%. The antenna under NFCS loading has a peak measured directivity of 21.6 dB, a 3 dB directivity bandwidth of 41% and a 10 dB return loss bandwidth of 46%, which covers the directivity bandwidth. The diameter of the proposed NFCS is $3.8\lambda _{0c}$ , which is around half that of all the other unit-cell-based phase-correcting structures, where $\lambda _{0c}$ is the free-space wavelength at the central frequency of the NFCS (13.09 GHz).