A fast computational technique for RF window in millimeter wave tubes

RF Window of millimeter wave tubes becomes very thin because of extreme high frequency, so that power capacity of the window is limited, manufacturing is difficult and it easy leaks. The equivalent circuit and computation are given for a type of ceramic block RF window with compensating irises. This RF window has higher power capacity, compact mechanical strength, easy manufacturing and airtight welding. The testing results show that the design method is fast and useful accuracy.     

A broadband Ka-band microstrip circulator for integrated millimeter wave systems

A Ka-band microstrip circulator, using ferrite with 4π M=5000 G, have been developed. By optimizing the circulator configuration, broadband n=2 Chebyshev response performance are obtained over 7 GHz bandwidth. The circulator have isolation of greater than 15 dB, and insertion loss of less than 1.0 dB.     

可扩展毫米波宽带隔离器的便捷设计

针对传统滤波器形状复杂、参数数值奇异、设计繁琐的问题,提出了一种结构简单、易于绘制的宽带隔离器。这种隔离器呈楔形,由外框和内轨组成。每根内轨贡献一个小阻带。隔离器的阻带结构可以由不同位置处的多根内轨组合形成。扩展阻带带宽,增加新阻带,只需增加内轨,而不用重新设计隔离器。使用HFSS电磁场仿真对设计思想进行验证,并就内轨间距、轨线宽度等参数进行了分析。还使用印刷电路工艺,设计了原型隔离器,并进行实测。仿真和实测结果吻合,都具备阻带带宽为10 GHz,相对带宽超40%的宽带效果。它的结构和设计过程简单,可方便地嵌入集成电路芯片电源网中,即使数字工程师也容易掌握。隔离器还具有良好的可扩展性,便于阻带调节。     

一种用于毫米波的共面波导间的宽带互联结构

在多芯片组件中,微波传输线间一般使用金丝键合的方式进行连接。受金丝自身的等效电感和其与基板及壳体间存在的寄生电容的影响,键合金丝结构在毫米波频段下带来了较大的阻抗失配。为了解决该问题,文中从等效集总元件角度出发,对阻抗变换公式进行了推导,分析得出串联低阻抗传输线可以等效为并联集总电容的结论,可以与键合金丝的等效模型一起,构成等效低通滤波器,完成阻抗匹配。文中使用共面波导结构制作了键合金丝匹配结构测试件,测试结果显示,在30～40 GHz内S_(11)<-20 dB、S_(21)>-0.2 dB,具有优良的传输性能。该结构具有较强的实用性,可以用于毫米波频段下的微波组件设计。     

宽带超短波射频前端的设计和实现

宽带超短波射频前端是软件无线电通信平台的关键部分之一。在此介绍了集成宽带调制芯片TRF372017和解调芯片ADRF6850,设计了宽带超短波射频模块的实现方案。基于这两款芯片分别实现了发送电路和接收电路,并结合软件无线电基带处理平台加载了宽带通信波形进行测试。测试结果显示,该射频模块具有较好的性能,且具有体积小,功耗低,增益控制范围大等优点。     

A broadband RF noise generator

A simple broadband noise generator was constructed which produced substantial noise power over the frequency range from 10 mc to 1,000 mc. The measured noise factors were 90 db or better over this range. The noise was generated by an electric arc discharge that operated in a conventional RC relaxation oscillator circuit. A continuous spectrum was produced because of the natural incoherence in the pulse repetition rate of such a circuit. The mechanism of operation is described, along with an experimental tube that was constructed for the purpose of demonstrating the principle.     

A millimeter wave broadband wireless access technology demonstratorfor the next generation Internet network reach extension

We report design and implementation scenarios for a gigabit-capacity and high-data-rate fixed wireless access technology demonstrator. The system is based on a broadband wireless access concept and implementation techniques utilizing millimeter-wave and newly introduced free-space optical wireless high-speed links. The demonstration platform is to provide broadband “last mile” access and networking solutions to Internet users in densely populated areas with homes and businesses (e.g., building-centric and inner city environments) in need of high bandwidth not served by the fiber infrastructure. The investigation focuses on the radio link design, network architecture, system integration, and a compatible interface to the existing ATM fiber and satellite core networks in support of the next-generation Internet (NGI) reach network extension by the wireless technology     

Precision broadband wavemeter for millimeter and submillimeterrange

A precise, broadband, Fabry-Perot wavemeter has been designed and built to measure wavelengths in the millimeter and submillimeter range. The design of the wavemeter is novel in that it enhances the fundamental mode over a wide band and permits determination of the exact longitudinal index of the mode. With the use of an exact mode number in wavelength calculations, high measurement accuracies, to the extent permissible by the quality factor of the resonator, can be obtained. The wavemeter was tested by measuring well-known spectral lines of the OCS molecule in the frequency range of 72-607 GHz. Measurement of 24 OCS lines demonstrated an accuracy of better than 2×10^-5 in relative units and 0.87×10^-5 in rms units for frequency/wavelength. A discussion of further development and automation of the wavemeter is included     

A taper filtering finline at millimeter wavelengths for broadband harmonic multiplication

The design of a taper filtering finline aimed at simultaneously mode matching and frequency selecting multifrequency signal is presented. Based on the superimposition of a smoothly corrugated taper and a sinusoidal-shaped filter, a low insertion loss (L<0.1 dB) at W band [75:110] GHz and a high rejected stop band in the third harmonic range (R band [225:330] GHz) are demonstrated. Both sections are numerically optimized using chain matrix techniques and assessed by means of full three-dimensional electromagnetic simulations.     

RF tubes for space-based accelerators

The authors analyze and classify high-power RF tubes for possible application to space-borne linear accelerators at frequencies of 425, 850 and 1700 MHz. Devices considered include relatively conventional tubes such as klystrons, klystrodes, magnetrons and crossed-field amplifiers; various novel devices such as the trirotron, timatron, lasertron and gigatron; Soviet accelerator tubes (the martotron, gyrocon and magnicon); the peniotron; and the resnatron. Primary factors considered in analyzing the devices were accelerator compatibility, weight, and efficiency. In addition, problems of thermal management, regulation, pulsing and operating voltage were addressed. Several suggestions, recommendations and results generated during the study are included     

A millimeter wave dielectric waveguide antenna

This paper describes the theoretical and experimental results of a novel leaky-wave antenna incorporating a homogeneous dielectric transmission line and radiating aperture into a single structure. The primary objective of this investigation is to demonstrate the ability to control aperture radiation by simply cutting slots into a metal-free dielectric transmission line. Experimental line source antennas with identical periodic slots were designed to operate in the 35 GHz frequency region. The successful performance of these antennas resulted in the design of a dielectric line source antenna with a symmetrical amplitude taper which provided a lower sidelobe level. The design represents a significant breakthrough in achieving affordable, low-loss, lightweight antennas in the millimeter wave region. The most significant applications for this type of antenna include radar surveillance and tactical missile-seeker terminal guidance.     

A study of millimeter wave cusptron

The interaction between electron beam and RF fields of H₈₁₁ π-mode in an eighth harmonic cusptron at f₀=35GH_z is studied numerically. The finite thickness and eccentricity of a rotating annular electron beam and the cusp magnetic field in the imbalance case (B_c≠?B₀) are considered in the mumerical calculation. The results show that these pratical factors have a great influence upon the electron efficieency.     

A novel millimeter wave gunn oscillator

It is described that the design, configuration and the performance of a novel millimeter wave Gunn oscillator stabilized by external cavity and temperature compensation in this paper. The frequency stability is 3.6 × 10^?6 at 52 GHz over the teperature range from ?10 to 50 °C. An output power of more than 100mW has been obtained in the frequency range from 51.5 to 52.8 GHz.     

High-power pulse millimeter traveling-wave tubes

A line of traveling-wave tubes operating in the 8-mm wave band with an output pulse power of 0.2–6 kW, which are suitable for application in transmitters of radar stations, is designed.     

0.14 THz折叠波导行波管盒型窗设计与制作

研究用于0.14 THz 折叠波导行波管的盒形窗结构,采用三维模拟软件 HFSS 进行计算与优化,设计出基于蓝宝石窗片的盒型窗结构.分析了结构参数对盒形窗电压驻波比的影响,主要结构参数在±0.01 mm范围变化时,盒形窗电压驻波比仍然低于1.2,保证零件加工的可行性.装配完成盒形窗测试结构,冷测结果显示,在0.135 THz~0.145 THz范围内衰减系数为0.7 dB左右,满足整管要求.     

A robust beam tracking scheme for millimeter wave HetNets

Millimeter Wave (mmWave) communication has been widely acknowledged as an attractive solution to address high-speed transmission of massive data in 5G and beyond 5G systems due to the promising spectrum availability. However, mmWave signals are highly susceptible to blockage and may suffer from rapidly changing channels. Thus, directional/beam tracking becomes imperative yet essential for robust mmWave communications. To address this challenge, we propose a robust beam tracking scheme for mmWave Heterogeneous Networks (HetNets) with multi-connectivity. Different from most existing schemes, the proposed beam tracking scheme is effective for outage events. We first discuss the μWave-assisted beam tracking procedure with and without candidate beams, and then analyze the inherent correlation between mmWave link quality and the operating beamwidth and occlusion range to derive the optimal beamwidth. Theoretical and numerical results show that the proposed beam tracking scheme can improve the robustness of mmWave communications while guaranteeing the rate performance.     

A large antenna array for millimeter wave propagation studies

An antenna array has been constructed for reception of line-of-sight, ground-to-ground transmissions at 35 GHz over a 28-km path. It measures, individually, the amplitude and the relative phase of the arriving wave at each of eight antenna elements spaced horizontally over a distance of 24 m transverse to the path. Preliminary observations have shown perturbations in amplitude which appear at one end of the array and progress sequentially in a matter of seconds from element to element across the array. Similar traveling perturbations occur in the phase measurements. Variations in tilt of the wave front are observed, usually amounting from a few to tens of seconds of arc. In addition, changes in wave-front curvature have been measured corresponding to an apparent shrinkage or expansion of path length on the order of ten percent. Other capabilities of the array as a propagation-research tool are mentioned.