Microwave Power Combining Techniques

A review of various techniques for coherently combining microwave power from two or more sources is presented. Emphasis is placed on techniques which combine solid-state power sources. Basic operating characteristics and limitations for the different combiner types are discussed. The performances obtained with the most successful techniques are described. Future trends in combining RF power from solid-state sources are identified.     

微波功率合成方法

本文对两个或多个信源微波功率合成方法作了回顾,重点放在非谐振腔合成方法上.同时也探讨了各种不同的合成方法的特性以及其局限性,描述了最有效方法的性能,指出了射频功率合成的未来发展趋势.     

Harmonic Power Combining Of Microwave Solid-State Active Devices

A method for combining the power in a selected harmonic of the fundamental frequency for a symmetrical array of oscillating solid-state devices is described and demonstrated. These combiners convert fundamental power to harmonic power with filtering accomplished by symmetry. This technique appears useful for improving the performance of microwave and millimeter-wave power sources by effectively enhancing the frequency-power limitations of existing solid-state devices. An example of the method is provided by a simple three-phase frequency-tripling varactor-tuned transistor oscillator.     

微波输能应用中整流天线阵列接收效率的研究

整流天线阵列是微波无线能量传输系统的重要组成部分,其接收和转换效率关系到能量无线传输的成败。在5.8 GHz频段采用矩形、圆形和三角形3种微带贴片单元,分别以发射天线阵列最大口径效率和接收天线阵列最高接收效率为目标进行优化,仿真计算了各天线阵列对空间电磁来波的接收效率。结果表明,天线单元形状会影响整流天线阵列的接收效率,相对于按发射天线阵列最大口径效率设计,以最高接收效率优化排布的整流天线阵列,对空间电磁来波的接收效果较好。     

On the Pressure Dependence of Microwave Crystal Rectifiers (Correspondence)

During the past couple of years, as a result of government interest, silicon microwave crystal rectifiers have not only decreased their noise figures but also have increased their resistance to adverse environments; i.e., high burnout, high temperature, excessive humidity.     

Excess Noise in Microwave Crystal Diodes Used As Rectifiers and Harmonic Generators

Excess noise produced by microwave excitation of silicon crystal diodes was studied for operation of the crystal as a detector and as a microwave harmonic generator. The noise appears at the detector terminals and also as noise sidebands of the microwave harmonic, thus degrading the spectral purity of the harmonic relative to that of the fundamental. Possible models of the processes involved are presented. Difficulties and technique of measurement are discussed. Observations for 1N26 crystals, used as detectors, doublers, and triplers, and excited by X-band power in the range 8 to 100 mw are presented, showing limitations on spectral purity set by the process of noise production during harmonic generation.     

A Multiple-Animal Array for Equal Power Density Microwave Irradiation (Short Papers)

The introduction of multiple subjects into a microwave field invariably results in perturbations and interference patterns which make it difficult to accurately determine power densities at any specified location. To overcome this problem, investigators have restricted the number of subjects, which is inefficient, or used techniques to illuminate large volumes, which still results in large variations in power density due to curvature of the microwave field. An exposure array has been devised that negates these disadvantages and enables simultaneous irradiations of multiple animals at uniform average power density (/spl plusmn/5 percent). The array consists of microwave transparent cages positioned in accordance with the natural characteristics of the microwave field and separated sufficiently to insure minimum interaction between animals due to microwave reflection. The results of testing the array in an anechoic chamber at a freqnency of 2450 MHz using an isotropic field probe are presented.     

基于外腔光纤激光器阵列频谱组束的耦合效率

分析了外腔高斯光束频谱组束的机理.针对Bochove推导点特征扩展系数所使用的方法繁琐问题,运用角特征的近似形式,推导了点特征的扩展系数;并基于频谱组束模型,讨论了影响耦合效率的因素.结果表明,外腔最大耦合效率时,激光器阵列应排列成开口背离传输透镜的抛物线形;当阵元的横向位移超过1.5 mm时,抛物线形排列的阵元耦合效率是相同位置直线形排列阵元耦合效率的2倍;使用外腔频谱组束,应尽量选择焦距较长的传输透镜.     

高频整流器的输入功率因数及整流效率

为了验证各种高频整流器在UPS中应用的优越性,文中分析了几种不同类型高频整流器的输入功率因数及整流效率,发现不是所有的高频整流器的输入功率因数及整流效率都高,只有IGBTBoostSPWMPFC高频整流器的输入功率因数大于0．99,UPS效率大于94％,证明有些人所说的“任何容量的高频UPS的输入功率因数都可以做到0．99以上”是不准确的。     

Synthesis and Validation of a Cu Meta-BasedWideband Microwave Absorber on an Antenna Array

Meta copper (Cu) material called nanotwin crystalline copper metal (C2101, Kopu Tharma Loham) fabricated on the basis of ancient Indian metallurgical techniques has been originally used here as an absorbing material. The research attempted here is to explore the electromagnetic properties experimentally over a wide range of frequency covering X, Ku, K and Ka bands. The dielectric constant and loss tangent of Cu meta material are high in the X range making it a good candidate for the successful design of an absorber. Along with that, the melting point of Cu meta is also increased to 1135°C which is otherwise 1085°C as per international copper standards, hence making the absorber thermally stable. The particle size of Cu meta material, when measured with the x-ray diffraction method, is decreased from 50 μm to 100 nm, placing it in a nanomaterial category. An absorption bandwidth of 35.58 GHz is obtained, ranging from 1 GHz to 36.58 GHz. After testing, the absorber is finally integrated with a two-element rectangular patch array for substantial applicability. The radiation pattern plot shows a remarkable reduction in side lobe level of the array from 3.737 dB to 1.158 dB after placing the Cu meta material absorber. The beam width narrows down from 70° to 44° with a slight increase in the amplitude of the major lobe from 5.494 dB to 6.341 dB while retaining the pattern symmetry.     

Efficient Power Combining

The objective of this paper is to establish understanding of the single/multimode oscillator circuits used in combiners. A model is developed with emphasis on the selection and realization of the input/output coefficients, optimum stabilizing and output loads, equalizing network synthesis, and other cogent features. The application of this theory to the highly successful and efficient design of J-band pulsed oscillators will be discussed.     

N路功率合成的失效分析

随着国内半导体工艺水平的不断提高,固态合成功率放大器也开始大量的被应用到各种微波工程之中.目前国内多种固态合成功率放大器的产品皆以多路波导合成的方式获得大功率.在使用这些多路合成结构对大量功率器件进行功率合成时,一个或者多个器件的失效将对总体的输出功率造成多大的影响使成为了大家极其关心的性能指标.文章对固态功率合成器进...     

CMOS射频功率放大器中的变压器合成技术

设计了一种可在CMOS射频功率放大器中用于功率合成的宽带变压器。通过对变压器的并联和串联两种功率合成形式进行分析与比较,指出了匝数比、功率单元数目以及寄生电阻对变压器功率合成性能的影响;提出了一种片上变压器的设计方法,即采用多层金属叠层并联以及将功放单元内置于变压器线圈中的方式,解决了在CMOS工艺中设计变压器时面临的寄生电阻过大及有效耦合长度不足等困难。设计的变压器在2～3 GHz频段内的损耗小于1.35 dB,其功率合成效率高达76%以上,适合多模多频段射频前端的应用。     

微波功率模块

综述了微波功率模块的研究与发展, 指出了微波功率模块的结构、原理与应用前景。     

微波功率异质结双极晶体管

本文首先简要介绍异质结双极晶体管(HBT)的结构和特点,接着评述HBT工艺技术发展现状、单元设计和目前制作的功率HBT的性能。     

EHF频段10 W连续波空间功率合成放大器

针对EHF频段卫星通信对固态高功率需求问题,提出一种空间功率合成放大器的设计方案,基于BJ400标准波导的波导T型结功率分配/合成器、H面波导3 dB分支线电桥和波导-微带探针变换相结合的合成高效、结构紧密的空间功率合成。借助三维电磁仿真软件HFSS对无源网络进行仿真优化,依托精密的机械加工技术,进而实现了8路功率合成。驱动功放和末级功放均采用GaAs MMIC功放芯片,实现最小10 W的连续波功率输出。测试结果表明,在EHF频段43~45GHz范围内,1 dB压缩点输出功率最小达到10 W,合成效率高于80%,在该频段上实现了高效率合成和大功率输出。此方案的结构具有尺寸容差大、易于制造和方便散热的特点,在工程应用中有很大的前景。     

共相位望远镜阵列的光束耦合问题研究

研究了共相位望远镜阵列的两种重要光束耦合误差——光瞳面平移(piston)误差和光瞳面倾斜(tilt)误差。设piston误差和tilt误差都服从均值为零但标准差待定的正态分布,根据中心点亮度判据,通过迭代方法计算了piston误差和tilt误差所允许的最大标准差,揭示了这两类光束耦合误差所允许的最大标准差与子望远镜个数和遮光比的关系。Piston误差所允许的最大标准差与子望远镜的遮光比无关,但随着子望远镜个数不断增加,在0.11λ～0.08λ范围内缓慢减小。Tilt误差所允许的的最大标准差在子望远镜出瞳大小已知的情况下,随遮光比不断增加而逐渐减小,而与子望远镜个数无明显的相关性。     

An Ordered Array of Terminated Metallic Posts as an Embedding Network for Lumped Microwave Devices

An ordered array of metallic posts is proposed as an embedding network for lumped devices at microwave frequencies. The individual metallic posts, terminated in a lumped device, extend across a parallel-plane transmission line excited by the TEM mode. In the analysis the impedance discontinuity for an individual terminated metallic post in a transmission line bounded on two sides by electric walls and two sides by magnetic walls is evaluated. Design concepts useful in employing these results with a two-dimensional array of metallic posts terminated with semiconductor devices are described.     

微波功率管壳封装

本文论述了微波功率器件和单片集成电路封装的重要性,及其工作原理、关键技术、封装材料的选择、管壳制造和密封技术、可靠性及结论。     

Control of the SAR Pattern Within an Interstitial Microwave Array through Variation of Antenna Driving Phase

The interstitial microwave antenna-array hyperthermia (IMAAH) system produces a pattern of specific absorption rate (SAR) that is nonuniform within a 2-cm square array driven in phase at 915 MHz. Theory and experiment show that the point of phase coherence (maximum SAR) can be shifted to a point where the SAR is small by changing the antenna driving phases. Rapid shifting makes the time-average SAR more uniform in the direction perpendicular to the antennas. In 95 percent of the antenna junction plane, the time-average SAR is constant within 10 percent.