Search

This article introduces design of two frequency reconfigurable rectenna arrays, which are in direct current (DC) combining and in radio frequency (RF) combining configurations, respectively, with the mutual coupling analysis. We compare the performances in the conversion efficiency of the two arrays. For the mutual coupling analysis, the coupling coefficient matrix and the active DC patterns of the two rectenna arrays are calculated. By analyzing the mutual coupling, we find that the rectenna array in RF combining can achieve higher and more stable output DC power than that in DC combining. When the receiving antenna element spaces about 0.46λ0 and the rectifying circuit element spaces 0.17λ0, the proposed two‐element reconfigurable rectenna array in RF combining configuration achieves measured conversion efficiencies of 69.1% and 64.2% at two operation frequency modes, while simulated efficiency in DC configuration achieves 70.3% and 53.2% when the rectenna element spaces 0.38λ0. [ABSTRACT FROM AUTHOR]

Abstract: In this article, a compact broadband rectifying antenna (rectenna) is proposed to harvest RF energy. A novel Vivaldi antenna is presented and an efficient rectifier with a single stub matching network is designed. Simulation and experiment have been performed and a good convergence is observed between the simulated and measured results. The experimental results show that the antenna features a broad bandwidth from 2.3 GHz to 2.85 GHz and the maximum conversion efficiency of the rectifier is up to 68% at 0 dBm. The maximum conversion efficiency and output voltage of the proposed rectenna are 58% and 1.6 V at 2.45 GHz under the input power of 0 dBm. [ABSTRACT FROM AUTHOR]

Abstract: In this article, a high gain rectifying antenna using a pair of pentagonal loops has been developed for wireless power transfer at 5.8 GHz. For a long range wireless power transfer, the rectenna system requires high gain and high conversion efficiency. The proposed rectenna system consists of a pair of pentagonal loop antennas to achieve high gain characteristics, an impedance transformer, and a rectifying circuit which are designed on a CPS (Coplanar stripline) structure. A metal reflector is also placed for achieving higher gain characteristics in a broadside direction. A CPS to microstrip line balun is designed to verify performance of the pentagonal loop antennas based on CPS structure. The fabricated pentagonal antenna demonstrates high gain of 10.1 dBi, and it results in receiving more RF energy from a designated source. An impedance transformer is designed to change the antenna's input impedance to diode's input impedance and block higher order signals coming back from the rectifying diode. To obtain high conversion efficiency, several load resistors are used. The proposed rectenna system based on CPS pentagonal loops shows measured conversion efficiency of 75% at 5.8 GHz, and its performance has been verified through simulation and measurement. [ABSTRACT FROM AUTHOR]

Abstract: A frequency reconfigurable miniaturized circular microstrip patch antenna operating in WiMAX (2.5–2.8 GHz) and ISM (2.4–2.48 GHz) frequency bands for the rectenna applications is proposed here. The theory of reconfigurability is employed to switch the operating frequency of the proposed antenna from 2.53 to 2.45 GHz. The electrical length of the radiated circular patch is increased while keeping the overall physical dimension of the antenna constant to provide different current distributions on the radiating patch for the phenomenon of frequency shift. The high permittivity substrate and microstrip transmission‐line feeding mechanism is used to reduce the size of antenna. To demonstrate the reduction in antenna size, a comparison of the proposed antenna with the latest antennas for rectenna applications in literature is presented. [ABSTRACT FROM AUTHOR]

A wireless power collection (WPC) system is proposed to harvest excess electromagnetic energies in space that are reflected and not received by target antennas. The radio frequency identification (RFID) system was utilized to demonstrate WPC. The power was transmitted between the reader and tags, and the rectenna (rectified antenna) was used to collect energy in our WPC system. The rectenna includes ultra-high frequency RFID tags. When the distance between the rectenna and the reader was 10 cm, the maximum voltages of a single rectenna and four rectennas in series were measured to be nearly 1.5 and 5.7 V, respectively. This WPC system can be used to supply power to charge batteries or other electronic products. A WPC tree consisted of four sets of rectenna arrays provided a charging current of ∼0.203 mA to a set of four AAA NiMH batteries. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article a novel 2.45-GHz ISM rectenna is presented. The linearly polarized rectenna uses two square patch antennas matched using a frequency selective surface before a dual diode rectification in series with the load resistance. Measurements showed a broad angle of energy reception and 79% RF-to-DC conversion efficiency. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2508-2512, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a compact design of shorted patch rectenna with the harmonic rejection properties for the applications of wireless power transmission. To improve the power conversion efficiency (PCE), the harmonic rejection filter widely used in the conventional design is removed from the circuit to reduce the insertion loss. Instead, the rejection of higher order harmonic noise that was generated from the rectifying diodes is achieved by etching a U-shape slot resonator on the shorted patch antenna. As a result, this method may improve the PCE without sacrificing the capability of higher order harmonic noise rejection. The design procedure and performance of the proposed shorted patch rectenna will be presented in detail in this article. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2250-2257, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT Microwave wireless power transmission (MWPT) is a new-style transmission mode, which has wide application on Space Solar Power Station (SSPS), Payload Spacecraft Module, high power weapon, and so on. Based on the requirement of space application, one MWPT system has been presented. The solid source provides microwave power. The diameter of transmitting paraboloid antenna is 2.4 m. The receiving antenna is an array rectenna, with the scale of 2.4 m*2.4 m. The transmission distance is 11 m. And the DC-to-DC transmission efficiency is better than 16.5%, which is admirably agreed with the estimation results. The experimental results could promote the theory study-engineering application conversion of MWPT technique. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1704-1707, 2016 [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a broadband circularly polarized (CP) rectifying antenna (rectenna) for microwave power transmission at 4.2-7.6 GHz, comprising a broadband CP antenna, and a rectifier circuit. The antenna consists of a standard Schiffman phase shifter and a pair of orthogonally positioned linearly polarized slot antennas with equal radiation strength. The rectifier circuit is composed of a microwave Si Schottky detector diode (HSMS-2862), a low-pass filter, a load resistor, and a ripple capacitor. Output dc voltage of 1.98 V over a 680 Ω load resistance and the maximum microwave-to-dc conversion efficiency of 81.6 % were measured when 34 dBm microwave power was transmitted at 5.6 GHz over a distance of 50 cm. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:702-706, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT A simple design for solar powered frequency sensors is presented. The design is based on a rectenna composed of a frequency reconfigurable microstrip antenna, a rectifying circuit, and a low pass filter. The operating frequency of the antenna can be tuned in the range between 2 and 2.8 GHz, and, in this frequency range, the rectifier can effectively perform the conversion from RF to DC. By the measured results of the rectenna, the average conversion efficiency within the operating bandwidth of 33% is 73% over a resistive load of 1 kΩ at a power density of about 0.8 mW/cm2. A frequency sensor is successfully implemented by integrating the frequency reconfigurable rectenna with a preprogrammed microprocessor powered by solar cells. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1739-1742, 2014 [ABSTRACT FROM AUTHOR]