Design and performance analysis of broadband rectenna for an efficient RF energy harvesting application

This article proposes the design of coplanar waveguide (CPW) fed broadband rectenna for radio frequency (RF) energy harvesting application. The rectenna is designed to operate in the industrial, scientific, and medical (ISM) frequency band of 5.8 GHz. For designing the proposed rectenna, polytetrafluoroethylene (PTFE) dielectric material was used to design, fabricate the CPW fed slot antenna. It was observed that the proposed antenna exhibits the |S₁₁| of ?23.43 dB and achieves the peak antenna gain of 8.56 dBi at 5.8 GHz. Secondly, the CPW fed rectifier circuit which comprises of the matching circuit, rectifying unit, and filter was designed. The measured results showed that the |S₁₁| of ?19 dB and it was perfectly matched with 50 Ω impedance. Finally, the rectenna was designed by integration of antenna with rectifier circuit. The simulated results showed the maximum RF to direct current (DC) conversion efficiency and the output DC voltage of 88% and 445 mV at the load resistance of 1 kΩ. The measured results show the maximum RF to DC conversion efficiency of 73.4% with the output DC voltage of 540 mV at the load resistance of 1 kΩ.     

Design of perfect electrical conductor wall‐loaded 2.45 GHz high‐efficiency rectenna

A 2.45 GHz industrial, scientific and medical band rectenna with a two‐layered structure for various applications involving microwave wireless power transmission (WPT) has been designed and measured in this article. A microstrip antenna with two perfect electrical conductor walls loaded for gain enhancement is designed. In addition, a typical single‐diode compact radio frequency (RF) rectifier with a series bandpass structure is presented. The simulated RF to dc conversion efficiency of the rectifier is above 50% when the input power ranges from 0 to 28 dBm. The fabricated rectenna is compact with a dimension of 0.5λ × 0.5λ. A RF to dc conversion efficiency of about 73% is achieved under received power density of 38.5 W/m² with a 500 Ω dc load. Due to the integration design of antenna and rectifier, the proposed rectenna is suitable to be well applied in miniaturization of rectenna array.     

Dual‐band aperture‐coupled rectenna for radio frequency energy harvesting

The article presents a dual‐band aperture‐coupled rectenna for radio frequency (RF) energy harvesting at 2.45 and 5 GHz application. The rectenna consists of a dual‐band π‐shaped slot‐etched aperture‐coupled antenna, designed at the lower substrate of two FR4 substrate layers and a dual‐band rectifier. The proposed antenna design also introduces the harmonic suppression of third‐ and higher order harmonics, ranging from 6 up to 10 GHz from the asymmetrical stubs design at the transmission feedline. The dual‐band rectifier is designed to operate at 2.45 and 5 GHz frequency, successfully achieving high conversion efficiency at 68.83% and 49.90% with the optimum load resistor of value 700 Ω and 1.1 kΩ. The minimum DC voltage of 0.167 and 0.236 V with 0 dBm RF input power can be increased when greater RF power is being applied to it, increasing its flexibility to cater various low‐power applications.     

An efficient dual‐band rectenna using symmetrical rectifying circuit and slotted monopole antenna array

In this article, an efficient dual‐band rectenna making use of the newly proposed symmetrical rectifying circuit working at the frequency of 1.8 and 2.45 GHz, is proposed. The proposed dual‐band rectifying circuit is combined with an array of compact wideband planar monopole modified circular slot antenna in order to facilitate the efficient rectenna design. The rectifying circuit employs symmetrical matching network in addition to the symmetrical rectifier thereby facilitating the suppression of the odd order harmonics. This eventually results into the higher output voltage as compared to the conventional rectifier circuits. Moreover, the dual‐band topology of the proposed rectenna increases the overall voltage by harvesting energy from two independent RF sources. The measured results of the fabricated structure show that the maximum RF to dc conversion efficiency of the proposed rectifier circuit reaches up to 70% at 9 dBm input RF power. From application point of view, the proposed rectenna circuit is tested to extract the RF energy from 1.8 GHz cellular and 2.45 GHz Wi‐Fi bands to energize a low‐power LED. The overall rectenna structure is reasonably compact providing good performance, which can potentially be employed for efficient wireless power transmission system.     

Compact circularly polarized beam‐switching wireless power transfer system for ambient energy harvesting applications

In this work, we propose a circularly polarized (CP) beam‐switching wireless power transfer system for ambient energy harvesting applications operating at 2.4 GHz. Beam‐switching is achieved using a low profile, electrically small CP antenna array with four elements and a novel miniaturized 4× 4 butler matrix. The CP antenna is designed with an e‐shaped slot and four antennas. The CP antenna measures 0.32 λ₀× 0.32 λ₀× 0.006 λ₀ at 2.4 GHz. The antenna has a gain of 3 dBic and an axial ratio less than 3‐dB at 2.4 GHz. A linear antenna array consisting of four elements is designed with the CP antenna element with an inter‐element distance of 0.29 λ₀ . A 4× 4 butler matrix with miniaturized couplers and crossovers are used to feed the four antenna array elements. Based on the input port of excitation, the main beam of the antenna array is demonstrated to be switched to four directions: ?5°, 65°, ?55°, and 20°. A CP rectenna is used to demonstrate the wireless power transfer capability of the combination of the butler matrix and the CP‐antenna array. The rectenna consists of a Teo‐shaped CP antenna and a rectifier. The open circuit voltage at the output of the rectenna is found to peak value of 30 mV at ?3°, 61°, ?53°, and 17°. Thus a complete system for CP wireless power transfer including the power transmission system as well as the RF energy harvesting sensor is designed and experimentally verified.     

A modified Hilbert fractal resonator based rectenna design for GSM900 band RF energy harvesting applications

This article proposes a novel rectenna design based on modified Hilbert fractal shaped microstrip antenna and Villard voltage doubler rectifying circuit for RF energy harvesting applications operating at Global System for Mobile Communications (GSM) 900 MHz band. The energy harvesting antenna is numerically optimized and fabricated on a Rogers RO4003 substrate of thickness 1.52 mm with a compact overall physical sizes of 80 mm × 82 mm (λ₀/4.16 × λ₀/4.06). Various geometric parameters and circuit component values of the proposed energy harvesting system are optimized in order to achieve a matched input impedance with good radiation performance of high gain for the input power level less than ?20 dBm. The numerical and experimental results point out the technical potential of the proposed rectenna design to be utilized in DC power supply modules of low voltage, low power electronic devices.     

Design and realization of an ultra‐low power sensing RF energy harvesting module with its RF and DC sub‐components

Herein, design, development, and analysis of ultra‐low power sensing energy harvesting modules and their subcomponents for ISM band applications have been studied with a holistic approach in an effort to achieve a feasible and high efficient RF energy harvesting performance. The complete harvester system designed and developed here consists of a zero‐bias RF energy rectifying antenna (rectenna), DC boost converters and energy storage super‐capacitors. Compared with the counterpart energy sources, the surrounding or transmitted wireless energy has low intensity which requires designs with high efficiency. To achieve a successful harvester performance, rectifier circuits with high sensitivity Schottky diodes and proper impedance matching circuits are designed. Dedicated RF signals at various levels from nanowatts to miliwatts are applied at the input of the rectenna and the measured input power versus the scavenged DC output voltage are tabulated. Furthermore, by connecting the rectifier to a high gain antenna and using a RF signal transmitter, the wireless RF power harvesting performance at 2.4 GHz was tested up to 5 m. The performance of the rectenna is analyzed for both low‐power detection and efficiencies. Impedance matching network is implemented to reduce the reflected input RF power, DC to DC converters are evaluated for their compatibility to the rectifiers, and super‐capacitor behaviors are investigated for their charging and storage capabilities. The measured results indicate that a wide operating power range with an ultra‐low power sensing and conversion performance have been achieved by optimizing the efficiency of the Schottky rectifier as low as ?50 dBm. The system can be used for battery free applications or expanding battery life for ultra‐low power electronics, such as; RFID, LoRa, Bluetooth, ZigBee, and low power remote sensor systems.     

An ultra‐wideband rectenna using optically transparent Vivaldi antenna for radio frequency energy harvesting

This paper presents a novel ultra‐wideband rectenna which consists of a transparent Vivaldi antenna and a wideband rectifying circuit for radio frequency energy harvesting. The antenna is realized on a 2.2‐mm‐thick soda‐lime glass substrate coated with fluorine‐doped tin oxide of thickness 650 nm. It provides an optical transmittance greater than 80% in the visible region. The rectifying circuit with a cascaded matching network and the Greinacher doubler circuit are fabricated on an FR4 substrate with a thickness of 0.8 mm. The antenna provides the best matching characteristics and the realized peak gain is 3.2 dBi. The designed matching network enables maximum power transfer from the antenna to the rectifier. The rectenna provides a peak power conversion efficiency of 69% for ?10 dBm input power. The proposed antenna can be realized on the windscreen of automobiles and glass windows without causing any obstruction to normal view.     

A compact omnidirectional dual‐circinal rectenna for 2.45 GHz wireless power transfer

A compact dual‐circinal rectenna with omnidirectional characteristic is designed for microwave wireless power transmission at 2.45 GHz. A novel dual‐circinal receiving antenna with the reflection coefficient of ?32.5 dB is proposed which is formed by expanding folded curves. By designing an impedance matching network with a 60 ° radial stub and a single stub, a rectifier is presented with the maximum efficiency of 55.6 % and the output dc voltage of 1.19 V under the input power of 0 dBm. Simulation and measurements have been carried out for the antenna and the rectifier. The measured results agree well with the simulated value. The results of rectenna experiment show that the maximum conversion efficiency is 51% at 2.45 GHz when the input power is 0 dBm. The proposed rectenna has the characteristics of compact size and omnidirectional harvesting which are advantageous in RF energy harvesting applications.     

GaN管芯射频功率放大器的研究

给出了一种基于GaN管芯的C波段射频功率放大器的设计方法。该方法采用CREE公司的CGH60120D芯片,并利用ADS软件对管芯模型进行负载牵引,以得到管芯的最佳阻抗值,然后设计管芯的负载匹配电路和直流偏置电路。最后对整个电路系统进行仿真,使其达到预期的功率值。     

基于无线传感器网络的高效整流天线设计

能够进行无线能量传输的整流天线技术是解决无线传感器网络能量供应问题的最佳技术手段。由此设计一种新型高效整流天线,采用将接收天线与整流二极管直接匹配的方法,在减小天线尺寸的同时提高了整流效率,在5.8 GHz下达到82.4%的转换效率,增加了整流天线的可串联性,能够更好地满足无线传感器网络的技术要求。     

A compact hollowed‐out loop rectenna without matching network for wireless sensor applications

In this article, a compact and high‐efficiency loop rectenna with matching network elimination for wireless sensor applications at 2.45 GHz is presented. The proposed hollowed‐out square loop antenna is designed and directly provides a conjugate matching to a compact voltage‐doubler rectifier. The loop rectenna can harvest microwave power without increasing the total size or affecting the performance of a wireless sensor. The experiment results show that the peak microwave‐to‐dc conversion efficiency of 74% is obtained at 2.45 GHz when the input power is 18 dBm. The dimension of rectenna is 30 × 30 × 1 mm³ and only with a weight of 0.58 g, which successfully realizes a high power‐weight‐ratio (PWR). Hence, the proposed rectenna can provide a convenient and practical charging solution for wireless sensors in various applications.     

A wideband rectifier array on dual‐polarized differential‐feed fractal slotted ground antenna for RF energy harvesting

This article reports a novel wideband rectenna for RF energy harvesting applications. A wideband fractal slotted ground antenna (SGA) is adopted. The operating frequency bands of the antenna are GSM, UMTS, Wi‐Fi, and LTE2600/4G bands. The antenna is fed by a dual‐polarized and differential‐feed (DP‐DF) microstrip lines disposed with an angle of 90° each relative to the other. The feed lines are etched on the bottom side of the substrate and connected to an array of four wideband RF‐to‐DC rectifiers. A nonuniform transmission lines filter ensures wideband behavior for each rectifier. The rectenna performances are simulated and measured. The experiments show an output DC voltage of 1 V at a power density of 26.6 μW/cm² over the frequency band of operation with a peak efficiency of 50%. The proposed rectenna is suitable for energy harvesting applications in urban environments.     

The design of radio frequency energy harvesting and radio frequency‐based wireless power transfer system for battery‐less self‐sustaining applications

In this paper, the RF energy harvesting system and RF‐based wireless power transfer system are proposed and designed for battery‐less self‐sustaining application. For energy harvesting, the designed antenna array improves the received RF power effectively and also can harvest RF energy in multi‐frequency bands. For wireless power transfer, the proposed helical antenna realizes the system design in miniaturization. Subsequently, the T shape LC matching network are designed between the antenna and the rectifying circuit to obtain more power transmission. The measured results show that the proposed Wi‐Fi rectifier and 433 MHz rectifier offer a maximum conversion efficiency of 66.8% and 76% in case of the input power is ?3 dBm and 0 dBm, respectively. Finally, the performance of the RF‐based wireless power transfer system and RF energy harvesting system are attested by experimentally measurement, the measured results indicate that these systems can be used to power electronic.     

基于BC5的蓝牙通信模块设计

采用CSR公司单芯片蓝牙IC—BlueCore5-Multimedia External(BC5)作为核心器件,以SST公司的Flash芯片SST39WF1601A-90-4C-B3K作为外围存储器件,用来存储系统固件、系统密钥和系统设置等,并设计了电源电路、晶振电路、天线接入电路和复位电路等外围电路,从而搭建出一个具有低成本、低功耗、小体积等特点的BC5蓝牙通信模块。     

A 2.4‐GHz dual polarized suspended square plate rectenna with inserted annular rectangular ring slot

This research has proposed a dual polarized suspended square plate rectenna for RF‐to‐DC conversion at the 2.40–2.50 GHz frequency band. The proposed dual polarized antenna yields improved isolation with an annular rectangular ring slot etched in the square radiating plate. The proposed antenna could achieve >40.00 dB isolation and >8.00 dBi gain with unidirectional radiation. The proposed SMS7630‐based rectifying circuits were measured and could realize the maximum conversion efficiency of 25.98% (1.57 V) with a 3.00 kΩ resistor and 2.00 mW input RF power of a signal generator. On integration, the experimental vertical polarization rectenna was capable of achieving the maximum conversion efficiency of 21.86% (14.20 mV) at the 0.5 m distance and 0.00015.00 mW/cm² input power density. The proposed dual polarized rectenna can receive the input RF power density of arbitrary polarization with obtained average conversion efficiency of 14.97% (10.50 mV) at the 0.5 m distance of wireless local area network (WLAN) system. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:164–173, 2016.     

RF–DC power conversion of Schottky diode fabricated on AlGaAs/GaAs heterostructure for on-chip rectenna device application in nanosystems

The Schottky diodes enjoined with coplanar waveguides are investigated for applications in on-chip rectenna device applications without insertion of a matching circuit. The design, fabrication, DC characteristics and RF-to-DC conversion of the AlGaAs/GaAs HEMT Schottky diode is presented. The RF signals are well converted by the fabricated Schottky diodes with cut-off frequency up to 25 GHz estimated in direct injection experiments. The outcomes of these results provide conduit for breakthrough designs for ultra-low power on-chip rectenna device technology to be integrated in nanosystems.     

低压电力线信道优化装置改进电路的设计

针对低压电力线信道噪声强、线路与负载阻抗失配严重的缺点，本文改进了现有低压电力线信道优化装置，设计了一种由6个分立元件组成的信道优化电路，结构简单，成本较低。在信号频率f≥2MHz的范围内，对其电路结构及性能进行了计算与仿真分析，证明该电路装置不仅能有效滤除来自家电的高频噪声，而且可以实现线路与终端负载的阻抗匹配功能，从而改善信道性能,提高信道容量。     

新型锯齿结构微带天线在整流天线中的应用

提出了一种新型带有V形锯齿结构的圆形微带天线,相比于传统的圆形微带天线,该结构微带天线在2GHz的S11值能够达到-26.9dB,二次谐波S11值能够达到-0.2 dB,三次谐波S11值能够达到-3 dB。由于这种良好的抑制高次谐波的作用,在组成整流天线时,可以省掉结构复杂、体积较大的滤波器。并且采用这种结构的天线,具有采用分形技术设计微带天线所获得的缩小天线尺寸的效果。对由该结构组成的整流天线进行仿真和实验测试,获得了超过2.7 V的DC电压,证明了其应用到整流天线中的可行性。     

A novel RF energy harvesting cube based on air dielectric antenna arrays

In this article, a new 2 × 2 circular microstrip antenna array with air dielectric layer for ambient RF energy harvesting has been proposed. Two pairs of arc‐shaped slots located close to the boundary of the circular microstrip patch have been designed for achieving dual‐band response and extending the frequency bandwidth. The antenna has a frequency bandwidth from 1.85 to 1.93 GHz and from 2.0 to 2.1 GHz which can cover GSM‐1800 and UMTS‐2100 bands. At the frequency of 1.89 and 2.05 GHz, the measured gain is 5.3 and 6.6 dBi, respectively, and high gain of 3.8‐9.3 dBi has been achieved over the whole band. Also, a broadband rectifier that can cover all the bandwidths of the antenna array is designed for the rectenna, which has the maximum rectifying efficiency of 53.6%. Finally, a cube device formed of four antenna and four rectifiers is designed to harvest RF energy, whose maximum output DC voltage is 2.3 V and the maximum output power is 4 mW that can drive four LEDs and an electronic watch.