1W微波无线输电系统的发射端设计

介绍了一种小功率(1 W)、2.45 GHz微波无线输电系统的发射端设计。直流电平经过锁相频率合成芯片ADF4360-0转换为S波段的2.45 GHz微波信号,ADF4360-0的寄存器配置由MSP430控制;2.45 GHz微波信号经过由功放芯片ERA-5SM及ADL5606组成的驱动级功率放大器将功率放大到1 W,加上喇叭天线即组成了小功率微波输电系统的发射端。利用矩形微带整流天线接收并整流微波信号,整流后的直流电平供给负载,便形成了完整的微波无线输电系统。详细分析了设计参数与方法,并进行了仿真及验证试验。     

X波段超轻薄整流天线设计

为解决无人机等移动目标领域的微波无线传能问题,文章设计了一种适用于微波无线能量传输系统中的10 GHz轻薄微波整流天线。该天线为线极化微带天线,天线印刷制作于厚度为0.254 mm(约0.008λ₀,其中λ₀为天线工作波长)的介质基板上,整流电路采用MA4E1317肖特基二极管作为整流器件,并且通过导电过孔与天线金属地相连接。该天线尺寸为117 mm×117 mm×0.254 mm。加工测试了整流天线样品,测试结果表明,该整流天线在天线接收功率为16 dBm时,整流效率达到62%。     

面向微小型机器人的5.8GHz微波能量传输系统

提出了面向微小型机器人的5.8 GHz 微波能量传输系统,采用Ritz-Galerkin（RG）方法建立了微波能 量传输系统射频整流电路模型,分析了整流二极管的整流性能,得到了输入功率与输出电压、整流效率与负载比之 间的关系．设计了八木振子天线,提高了能量接收的定向性．最后搭建了微小型机器人微波能量传输实验系统,开 展了利用微波传输能量驱动微机器人的实验,验证了利用微波能量传输系统为微小型机器人供能的可行性．     

利用电化学效应的微波剂量测定法

本文介绍一种测量能量密度的机内仪表,其外形尺寸为3厘米×3.5厘米×5厘米,重17.7克,利用一个0.12λ(1.5厘米)的偶极天线接受2450兆赫的微波电流。微波电流是通过肖特基(Schottky)势垒二极管整流,在此时间内用一个电解槽将微波功率转换成电化学效应剂量之。研究了电子元件的选择,讨论了仪表对5～50毫瓦/厘米_2微波辐射的响应,并提出了几个进一步研究的建议。     

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。     

一种超宽带能量收集整流天线设计

为了更好地利用空间无线电波RF能量,设计了一款覆盖谐振频率为1～14 GHz宽带天线,并针对2.4 GHz进行整流天线设计.天线主体为一个圆形贴片,在地面通过开圆形槽的方式,改变辐射单元表面电流强度,实现宽带谐振和增强辐射的作用.天线在2.4 GHz处为最佳谐振点,此频段对应的最大增益为6.26 dBi.为了使整流天线...     

共面波导馈电平面小型化超宽带天线设计

超宽带(UWB)系统的工作频段与现有的全球微波互联网接入(Wi MAX)、无线局域网络(WLAN)系统等窄带系统的频段相互重叠,会导致系统相互干扰。为了有效抑制现有窄带系统对超宽带通信系统的干扰,在单极子天线的基础上,通过在带有L型分支结构的矩形辐射贴片上开槽的方法,设计了一款具有双陷波的超宽带天线。当电压驻波比小于2时,天线工作频率范围是2.5~16 GHz,其阻抗带宽为13.5 GHz。该天线最大的特点是在Wi MAX(3.4~3.69 GHz)以及WLAN(5.15~5.825 GHz)的频率范围具有双陷波特性,能够降低Wi MAX和WLAN对系统的干扰。同时,天线采用共面波导馈电,具有良好的共面特性。仿真和测试结果表明:该天线在超宽带频率范围内具有良好的陷波特性,能有效抑制现有其他窄带系统的干扰。与传统的超宽带天线相比,该天线在尺寸和带宽上具有很明显的优势。     

矩形件排样优化的一种近似算法

本文对理论上属于ＮＰ－完备问题的二维矩形件优化排样问题，构造了一个效率高、速度快、可令人满意的一种近似算法，该算法的主要思想是在排样过程中根据一种局部最优原则不断地动态产生一些较小的矩形，然后对这些小矩形区域排样，同时也消去一些已排过的矩形区域，直至所有的矩形件被排完，根据本文算法我们开发了一个矩形件排样系统。     

基于三维空间均匀矩形阵列的MIMO系统研究

主要研究MIMO天线阵列系统性能,包括MIMO空间时间相关性和天线阵列配置。推导了三维多径信道中均匀矩形阵列在多种角能量分布下空间衰落相关性公式。采用多重信号分类算法对MIMO系统波达信号方向进行空间谱估计,推导了多种天线阵列空间谱通用公式。通过计算机模拟仿真验证分析结果,仿真结果表明方位角扩展是天线间空间衰落相关性的主要决定因素,在低方位角扩展时,俯仰角扩展对性能影响也是明显的。结果表明在同样的参数情况下估计MIMO系统空间谱时,采用三维均匀矩形阵列是有优势的。     

单层超宽带微带贴片天线的设计与分析

该文提出了一种新颖超宽带微带天线。该天线由微带宽槽天线的基本结构变形而来,其结构由矩形馈电微带贴片与矩形宽槽孔贴片组成。矩形宽槽孔开在金属GND板上,而矩形馈电贴片在介质板的另一面并在矩形宽槽孔框内偏下方。贴片与馈电线对接处采用渐变结构来达到阻抗匹配。以矩形宽槽尺寸为主构成了低频段的等效谐振电长度,而馈电贴片尺寸构成了高频段的等效谐振电长度。在各自的谐振频区上,矩形宽槽与馈电微带贴片两者相互耦合,构成两谐振电长度的天线叠合组成为一共面天线,从而拓展了天线的带宽。该文运用HFSS仿真软件,根据设定尺寸进行了仿真设计,制备了两只不同频段的样品天线。仿真结果和实验结果基本一致,表明该原理设计出的天线可实现超宽带特性。     

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.     

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.     

A radio frequency and vibration energy harvesting antenna based on piezoelectric material

This article proposes a novel hybrid energy harvesting antenna that can be used to harvest radio frequency (RF) and vibration energy in ambience. A microstrip antenna is designed on the piezoelectric film with the material of polyvinylidene fluoride (PVDF). Due to the high dielectric constant of PVDF, the antenna size can be reduced efficiently. The shape of designed microstrip antenna is trapezoidal, the final antenna size is reduced to 50 mm × 30 mm × 0.2 mm. To improve the efficiency, the rectifier with matching network is optimized and the modes of the piezoelectric film are analyzed. The experimental results show that the frequency bandwidth of the antenna is 2.1 to 2.5 GHz. For a RF source at distance of 1 m away, with a 0.25 W EIRP 2.4 GHz transmitter, the output power of the antenna can reach 17.2 μW. While under 17 Hz vibration excitation, the output voltage and power can reach 1.44 V and 15.3 μW, respectively.     

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.     

可调谐矩形环DGS的滤波特性研究

提出了一种新颖的可调谐矩形环缺陷接地结构（DGS）,可以用来实现微波滤波器。对矩形环DGS进行了精确的时域有限差分法（FDTD）数值分析,研究了其几何尺寸变化对阻带特性的影响。将FDTD计算结果与有关文献的测量结果进行了比较,一致性很好,从而验证了FDTD程序的有效性和计算的正确性。在微带平面添加短截线,研究了短截线的尺寸变化对阻带特性的影响。通过研究可知,可以通过改变矩形环DGS的几何尺寸去调节该结构的截止频率,也可以通过调节短截线的尺寸来改变该结构的阻带特性。这种关系能为可调谐矩形环DGS的分析和设计提供有力的指导。     

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.     

A study of spin rectification effect enhancement of microwave field by a PIFA

The progress of spin rectification effect, which has the potential in powering the nanoscopic devices wirelessly, has been impeded by its low conversion efficiency. To solve this problem, a 5.8 GHz planar inverted F‐shaped antenna, which is designed to harvest radiated microwave power as well as foster a field enhanced area surrounding a permalloy (Py, Ni₈₀Fe₂₀) monolayer, is presented. The electric and magnetic field are enhanced by ~17.5‐fold and ~ 45‐fold, respectively. With the proposed antenna, a photovoltage of 0.85 μV can be detected in the monolayer 1.5 m away from the transmitting antenna, with input power of 30 dBm. This work provides an effective method to enhance the spin rectification effect signal in the far field region and paves the way for spintronic devices to be potentially utilized in practical wireless applications, such as quantum information, photovoltaics, and nanogenerator.     

宽频带高增益RFID微带天线阵设计

设计了一种宽频带高增益微带天线单元并组成了4元阵列。通过在普通矩形微带贴片加载2个对称切角、改变贴片表面电流分布实现天线单元的双频工作,调节切角尺寸使两个频点相互靠近融合,展宽频带。在此基础上确定合适的阵元间距,采用等副同向并联馈电,馈电网络由T型结功分器组成,并使用同轴探针馈电方式,实现天线阵列的设计。通过高频电磁结构仿真软件HFSS对天线进行仿真和优化,结果表明阵列天线性能良好。     

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.     

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.