交叉场中曲线电子注的研究

对于交叉场系统,本文依形成电子注的综合法,导出了阴极处于任意状态下求空间电荷流和电极形状的普遍解,计算并分析了据此建立的磁控注入式电子枪和正交场电子枪的特性,讨论了阴极表面电场强度和电子初速对电子轨迹和电极形状的影响。     

S波段连续波SiC功率MESFET

利用国产SiC外延材料和自主开发的SiC器件工艺加工技术,实现了SiC微波功率器件在S波段连续波功率输出大于10W、功率增益大于9dB、功率附加效率不低于35%的性能样管,初步显现了SiC器件在S波段连续波大功率、高增益方面的优势。与以往的硅微波功率器件相比,在同样的频率和输出功率下,SiC微波功率器件的体积不到Si器件的1/7,重量不到Si器件的20%,其功率增益较Si器件提高了3dB以上,器件效率也得到了相应的提高。同时由于SiC微波功率器件的输入、输出阻抗要明显高于Si微波功率器件,在一定程度上可以简化或不用内匹配网络来得到比较高的微波功率增益,这就为器件的小体积、低重量奠定了基础,也为器件的大功率输出创造了条件。     

W 波段回旋行波管双阳极磁控注入电子枪的设计

回旋行波管是大功率、高频率的微波毫米波器件。根据W波段回旋行波管的要求,设计了双阳级磁控注入电子枪。由电子光学理论,计算得到电子枪的初始参量,然后利用粒子模拟软件MAGIC构造电子枪模型,分析电子枪各个参数对电子注性能的影响,为电子枪设计优化提供了一定的依据。最后优化得到符合设计要求的低速度零散电子枪结构。电子枪阳极电压为70kV,电流10A,电子注速比1.07,电子注横向速度零散0.8%。     

X波段相对论返波管卡诺枪设计

设计了一种用于X波段相对论返波管的电子枪,利用粒子模拟软件对整管进行测试,结果表明,这种电子枪能产生电流为4kA电压为550kV电子注,且具有使用寿命长,整管真空度高,性能好,可获得高重复频率输出等优点。获得了频率为10．34GHz,微波峰值功率1．5GW,转化效率为20％的微波输出。     

介质谐振器稳频的微波自振混频器

介绍了利用介质谐振器稳频,用场效应管(FET)或双极型晶体管制成的微波自振混频器的工作原理、实验电路及测试结果。实验表明,在X波段使用FET混频器变频增益达5.8dB,噪声系数为13.0dB。在C波段使用双极型晶体管,获得变频增益为4.8dB。     

介质支撑曲折线简介

一、引言介质支撑曲折线是最近在研制正交场放大管的过程中发展起来的一种大功率、宽频带慢波结构。由于它的成就,使注入式正交场放大管在C波段和S波段的倍频程带宽内能获得一千瓦的连续波输出功率和十千瓦的峰值输出功率。采用介质支撑曲折线,还可以使体积小、重量轻著称的正交场放大管的体积和重量进一步大为减小。例如,一支采用介质支撑曲折线作为慢波结构的S波段注入式正交场放大管可成功地包装在24×12×11立方厘米的体积内,其包括磁钢在内的整管总重量仅为4.3公斤。     

小型L波段GaAs双栅场效应管混频器的设计和性能

本文叙述了用于L波段微波接收机的砷化镓双栅场效应管混频器的设计考虑和实验结果.包括中频匹配网络,整个电路制作在30×40mm~2复合微波介质基片上.获得8.1dB的变频增益和5.9dB的噪声系数.研究了本振功率P_(Lo)、信号功率P_s和直流偏压V_(g1s)、V_(g2s)对变频增益G_c和噪声系数N_F的影响,并给示了最佳条件.     

微波低噪声SiGe HBT的研制

利用3μm工艺条件制得SiGeHBT(HeterojunctionBipolarTransistor),器件的特征频率达到8GHz.600MHz工作频率下的最小噪声系数为1.04dB,相关功率增益为12.6dB,1GHz工作频率下的最小噪声系数为1.9dB,相关功率增益为9dB,器件在微波无线通信领域具有很大的应用前景     

X波段低温低噪声宽带放大器的研究

阐述利用HEMT微波器件在低温下噪声显著降低的特性,研制X波段低温低噪声放大器的过程.分析了在低温下HEMT器件良好的噪声特性和微带线插损显著降低的特点.采用微波宽带匹配技术,设计并制作出宽带低温低噪声放大器.在液氮温区,其主要性能指标为:工作频率8～10GHz,增益＞26dB,噪声系数≤0.4dB.     

微波低噪声SiGe HBT的研制

利用3μm工艺条件制得SiGe HBT(Heterojunction Bipolar Transistor),器件的特征频率达到8GHz.600MHz工作频率下的最小噪声系数为1.04dB,相关功率增益为12.6dB,1GHz工作频率下的最小噪声系数为1.9dB,相关功率增益为9dB,器件在微波无线通信领域具有很大的应用前景.     

Minimum noise figure for magnetron injection guns

A minimum noise figure has been derived for the magnetron injection gun. This theoretical expression is based upon RF equations which were developed to calculate the transport of current and velocity fluctuations along a planar 3-dimensional space-charge flow. Current and velocity fluctuations at the magnetron gun output were found to be correlated regardless of the assumed cathode conditions. The resultant minimum noise figure expression incorporating correlation is valid for any planar, lossless O-type device utilizing a magnetron injection gun. The variations of magnetron gun-velocity fluctuations, current fluctuations, and minimum noise figure versus transit angle and cathode-magnetic field angle were plotted assuming that the noise at the potential minimum consisted of the traditional values of uncorrelated shot current and mean-square velocity fluctuations. The noise figure for the other values of the dc magnetron-gun parameters and assumed cathode-noise conditions are easily calculated since all expressions are in closed mathematical form. Comparisons between this theoretical minimum noise figure and the noise performance of an operational multicavity klystron were made.     

Noise measurements on a magnetron injection gun beam

The results of noise measurements conducted on a helix-type traveling-wave amplifier containing a magnetron injection gun are described. A minimum noise figure of 15.3 dB was observed at 760 MHz with an approximate beam power of 1600 watts. The noise figure was minimized by an adjustment of the magnetic field, which determines the transit time of the electrons through a drift region. This optimizes the magnitude and phase of the standing noise waves at the helix input.     

Transformation of fluctuations along magnetron injection beams

A generalized set of equations for evaluating transformation of fluctuations from one plane to another plane along the beam is derived by using the perturbation method. These equations are derived for the case of a magnetron injection gun and can be reduced to Llewellyn-Peterson and Van Duzer equations for O-type and M-type (Kino gun) configurations by appropriate substitution for the value of the angle θ (the angle between the cathode plane and the direction of the magnetic field). The noise transport coefficients for the case of a magnetron injection gun are evaluated both for temperature-limited and space-charge-limited cases and for several values of the perturbation frequency and angle θ. For the space-charge-limited case, both short and long Kino guns are considered. It is found that the values of the various noise transport coefficients which contribute toward noise at the output are reduced as the value of angle θ is increased. The results given in this paper indicate qualitatively that the noise content in a device using a magnetron injection gun is reduced as the value of θ is increased; this is in agreement with the previous results. For a quantitative evaluation of noise output, it is necessary to take into account the beam current and the various fluctuations simultaneously.     

Computer Simulation of Axis-Encircling Beams Generated by an Electron Gun with a Permanent Magnet System

Results from computer aided design of a novel electron gun generating axis-encircling beams are presented and discussed. Numerical experiments were performed by the new version of the software package GUN-MIG named GUN-MIG/CUSP. It is based on a self-consistent relativistic model and is developed as a problem oriented tool for analysis of electron-optical systems with magnetron injection guns (MIG) and electron guns with field reversal (cusp guns), forming axis-encircling beams. As a result of the simulations an electron-optical design of a novel electron gun with permanent magnet system was accomplished. The gun is expected to form high quality beams with small velocity spread and beam ripple. Parameters of the generated beams are appropriate for a prospective weakly relativistic high harmonic large orbit gyrotron (LOG). The development of such device is in progress now at the Research Center for Development of Far-Infrared Region (FIR Center) at Fukui University.     

50-nm T-gate metamorphic GaAs HEMTs with f/sub T/ of 440 GHz and noise figure of 0.7 dB at 26 GHz

GaAs-based transistors with the highest f/sub T/ and lowest noise figure reported to date are presented in this letter. A 50-nm T-gate In/sub 0.52/Al/sub 0.48/As/In/sub 0.53/Ga/sub 0.47/As metamorphic high-electron mobility transistors (mHEMTs) on a GaAs substrate show f/sub T/ of 440 GHz, f/sub max/ of 400 GHz, a minimum noise figure of 0.7 dB and an associated gain of 13 dB at 26 GHz, the latter at a drain current of 185 mA/mm and g/sub m/ of 950 mS/mm. In addition, a noise figure of below 1.2 dB with 10.5 dB or higher associated gain at 26 GHz was demonstrated for drain currents in the range 40 to 470 mA/mm at a drain bias of 0.8 V. These devices are ideal for low noise and medium power applications at millimeter-wave frequencies.     

Noise-Reduction Effects of Oven Magnetron With Cathode Shield on High-Voltage Input Side

A magnetron with a metallic cathode shield on the high-voltage (HV) input side is newly designed for the purpose of reducing the spurious noise generated from an oven magnetron. In this paper, it was experimentally found that the newly designed magnetron suppressed the sideband noise around the carrier frequency up to 10 dB, compared to the conventional magnetron. Moreover, both the spurious noise in the high frequency bands (4–14 GHz) and the line noise in the low frequency bands ($sim$1 GHz) from the newly designed magnetron were reduced up to 30 dB, compared to the conventional one. It was also found that a cathode shield attached to only the HV input side was more effective than the cathode shields attached to both the HV input side and the RF output side, with respect to the noise reduction. The thermionic emission from the cathode filament and the motions of the electrons in a magnetron are discussed in investigating the noise-reduction mechanisms.     

Theory of cathode trajectory characterization by canonical mapping transformation

The paraxial lens theory cannot directly be applied to the cathode trajectories inside the gun. This inconvenience makes the interpretation of cathode trajectories difficult since one cannot use the physical concepts familiar in the paraxial lens theory, such as focal length and magnification factor. We have proposed the canonical mapping transformation (CMT) to describe the electron trajectories inside the gun by relating the ray conditions on the cathode surface to those in the crossover plane. The method takes as variables the distance along the surface and the sine of the ray angle with respect to the surface normal to define ray conditions. It has been shown that the CMT can be characterized by a small number of optical parameters. One of the parameters is the 'electron gun focal length', an extension of the image side focal length in the paraxial lens theory. The crossover size of a triode gun can be calculated from the electron gun focal length and the initial transverse energy spread. The calculation predicts the dependence of the crossover size on the grid voltage due to the change in the electron gun focal length. The prediction is compared with the measurement and shows good agreement with it. Since the CMT optical parameters can be calculated from the representative trajectories only and as they predict practically all the necessary source properties of guns, the CMT can be used as a practical tool in the designing of various types of electron guns.     

Computer experiments on electron guns

Computer techniques for analyzing an axially symmetric or two-dimensional electrode system with an emitting surface can be used to obtain cathode current density distribution, beam minimum radius and its location, as well as possible electrode current interception. Here, comparison is made of available experimental data from two axially symmetric Pierce-type guns. The choice of the two axially symmetric Pierce-type guns was made for their different value of PV/T ratio, an invariant for transverse scaling. One of them has a low ratio of PV/T(approx 0.1 times 10^{-6}), which signifies considerable beam spread due to the effects of the Maxwellian velocity distribution of the thermal electrons leaving the cathode. The other gun has a high perveance of2 times 10^{-6}, and thus relatively high PV/T ratio where beam spreading is mainly due to space-charge forces alone. Good agreement with experimental data is shown. Computer techniques of this type can be a valuable tool for diagnostic purposes of any type of space-charge-flow devices (e.g., electron guns, ion guns for space propulsion, linear accelerators, etc.) and enable the engineer-designer to arrive quickly and cheaply at an optimum configuration.     

微电真空折叠波导行波管放大器的电子枪设计

研制工作于太赫兹波段的微电真空折叠波导行波管(FWG-TWT)放大器,需要设计束流集中且发射度小、结构紧凑的热阴极电子枪.本文首先依据典型皮尔斯电子枪的设计理论,通过编程计算初步选定了热阴极电子枪的基本结构参数,然后利用模拟工具对电子枪的结构参数模型进行了初步的仿真优化.针对工作频率为0.22 THz的微型折叠波导行波...     

基于GaN HEMT的13～17 GHz收发多功能芯片

基于GaN高电子迁移率晶体管(HEMT)工艺设计制作了一款收发(T/R)多功能芯片(MFC),主要用于射频前端收发系统.该芯片集成了单刀双掷(SPDT)开关用于选择接收通道或发射通道工作,芯片具有低噪声性能、高饱和输出功率和高功率附加效率等特点.芯片接收通道的LNA采用四级放大、单电源供电、电流复用结构,发射通道的功率放大器采用三级放大、末级四胞功率合成结构,选通SPDT开关采用两个并联器件完成.采用微波在片测试系统完成该芯片测试,测试结果表明,在13～ 17 GHz频段内,发射通道功率增益大于17.5 dB,输出功率大于12W,功率附加效率大于27％.接收通道小信号增益大于24 dB,噪声系数小于2.7 dB,1 dB压缩点输出功率大于9 dBm,输入/输出电压驻波比小于1.8∶1,芯片尺寸为3.70 mm×3.55 mm.