Accurate analysis and design of millimeter wave mixers

The present study is based on the method introduced by B. Shuppert (1986) for nonlinear analysis of mixers, but it differs in the linear part. In particular, the circuit characterization of the mixer harmonics is emphasized, removing the usual approximation of matched terminations and employing models that effectively represent network characteristics in the microwave and millimeter wave domain. This goal is achieved through the accurate knowledge of the various components used in the mixer and the use of accurate equivalent circuits. In order to validate the model, two subharmonic mixers operating at K-band (18-26 GHz) were realized. Reasonable agreement between theoretical and experimental results is achieved     

Cryogenic cooling of mixers for millimeter and centimeter wavelengths

It is shown theoretically that cryogenically cooling a Schottky-barrier mixer only slightly increases the conversion loss while giving a considerable reduction in mixer noise. The d.c. bias and local oscillator drive must be appropriately scaled. Experimental results indicate that in conjunction with a cooled paramp IF amplifier, single-sideband (SSB) receiver noise temperatures of ~350 K at 85 GHz, and ~260 K at 33 GHz are presently obtainable-an improvement by a factor of 6 at 85 GHz and 4 at 33 GHz over current room-temperature mixer receivers. An unexplained source of noise within the diodes has been observed and if this can be eliminated a further factor of 2 improvement in noise temperature will be obtained.     

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.     

5G毫米波OTA系统不确定度评估

5G毫米波频段有许多应用场景。毫米波采用了波束赋形技术,需要基于天线阵列实现。由于毫米波射频前端高度集成,一般不具备射频测试接口,几乎所有的测试项目需要在空口(Over-The-Air,OTA)环境下进行,因此一个可靠、稳定的测试环境是保证测试结果准确的必要条件。然而,OTA系统是由暗室、射频线缆、转台等多个部分组成的复杂测量环境,每一个环节都可能引入相应的测量不确定度,并且传递到最终的测量结果上。此外,毫米波测量具有频率高、损耗大的特点,相对低频更难保证测量系统的可靠性,因此对毫米波OTA系统不确定度的研究具有重要意义。结合典型的5G毫米波OTA测量环境对系统不确定度进行阐述与分析。     

A novel general approach for the optimum design of microwave andmillimeter wave subharmonic mixers

The design of subharmonic mixers is complicated and involves separation of signals and application of correct loading at the important idler frequencies. In this paper we present a novel general approach, which enables the designer to establish the optimum loading conditions for the different signals to get low conversion loss and good matching simultaneously. The method is demonstrated by a design example using a 30 GHz X2 subharmonic mixer. In this example it is shown that a nonoptimal design can yield conversion loss of up to 13.5 db, while an optimal design yields a conversion loss of 3.6 db     

Modeling and analysis of distributed millimeter wave massive MIMO system using Poisson point processes

Wireless Networks - This paper studies a downlink distributed millimeter wave massive multi-input multi-output (D-MIMO) system with radio access units (RAUs) and user equipments (UEs) following...     

Packaging and interconnects for millimeter wave circuits : A review

Interconnect and packaging techniques are major preconditions for a successful introduction of millimeter wave systems. This contribution give an overview on millimeter wave aspects of this topic including a number of examples covering front-end architecture, materials, circuit interconnects, package feed-through elements, and two complete mm-wave front-ends.     

A solder-free interconnect approach for integrating millimeter wave high-power devices with planar circuitry

The development of commercial millimeter wave systems requires cost-effective, high-performance device/circuit assembly techniques. A solder-free thermosonic bonding approach is described here to integrate millimeter wave high-power devices with associated planar circuitry. The devices with integrated heatsink are attached to a metal block, and then ribbon bonded with planar millimeter-wave transmission line circuitry using the developed solder-free thermosonic bonding process. The assembly process is designed to minimize the stresses that damage the devices, while maintaining the bond integrity. Observations confirm that the introduction of ultrasonic energy into the bonding process significantly reduces the temperature and assembly force applied to the device. The effects of different assembly parameters on the performance of the device are also presented.     

地球同步轨道星载毫米波降雨雷达数据模拟及地表杂波抑制

首先对地球同步轨道星载降雨雷达进行了介绍;其次基于其技术参数,利用美国第二代机载降雨雷达(APR-2)的实测数据模拟了地球同步轨道星载毫米降雨雷达的数据并对模拟的强度和速度场数据进行了分析;最后根据时域信号(I、Q)和功率谱数据的特征,采用时域无限脉冲响应(IIR)椭圆滤波器和频域高斯模型自适应处理(GMAP)两种方法对地表杂波进行了抑制,并对抑制前后的廓线数据和回波图进行了对比分析.结果表明,采用IIR和GMAP方法能够对受弱风条件下海面杂波影响的近地面气象回波进行较好的恢复,对地表杂波具有较好的抑制效果.     

The key technologies of millimeter wave MIMO communication system in space information network

With the rapid development of space information network and the increasing expansion of mankind activity,the requirements of communication quality become higher between mobile satellites and earth stations.In order to meet the demands of high data rate,large capacity and broadband real-time communication,applying millimeter wave frequency band to mobile satellite communication system has attracted great attention.Beamforming,tracking and channel estimation were introduced in millimeter wave MIMO system to fully understand the challenges of space information network which will face in the future.     

Slot integrated circuits of the millimeter wave band: A review

The results of mathematical simulation, investigation of electromagnetic phenomena, and development of millimeter-band devices designed on the basis of slot integrated circuits are reviewed. Advantages of these integrated circuits and the main contradictions limiting potentialities of such devices are analyzed. Prospects for further development of these structures are considered.     

Hybrid distributed online and alternating convex optimization-based initial value accelerated hybrid precoding for millimeter wave multiple-input-multiple-output

The hybrid precoding problem is considered a Frobenius norm reduction problem for the narrowband channel in a millimeter wave (mmWave) with multiple inputs and outputs (mmWave MIMO). This work proposes a hybrid distributed online and alternating convex optimization (HDO-ACO) algorithm to improve hybrid precoding (HP), interpreted as a trace minimization problem. HDO-ACO alternately determines the digital and analog precoders to reduce the trace by keeping the other constant. Initially, HDO-ACO uses Lagrange's method to determine the digital precoding subproblem. Then, it uses the integrated distributed online convex optimization and alternating minimization algorithm in the analog precoder design. In the HP method, the digital and analog precoders are iteratively updated until the highest number of iterations or convergence is reached. But this hybrid precoding method requires an initial analog precoding matrix input to begin the iteration. The algorithms converge gradually and fall into a suboptimal solution when the initial analog precoding matrix is set randomly. Hence, an initial value acceleration-based heuristic approach is used in the HDO-ACO alternating minimization algorithm that calculates the initial feasible value of an alternating minimization method using channel conditions. The simulation results of the proposed HDO-ACO algorithm are presented under bit error rate (BER), spectral efficiency (SE), and convergence behavior by comparing it with modified block coordinate descent–HP (MBCD-HP), manifold optimization–alternating minimization (MO-AltMin), and semi-definite relaxation-based alternating optimization (SDR-AO). The proposed HDO-ACO attains maximum SE and less BER than other hyper-precoding designs.     

Accurate evaluation of a millimeter wave compact range using planar near-field scanning

Significant progress has been made in recent years on planar near-field measurements for antenna calibrations. Such measurements are also useful in the alignment and evalnation of compact ranges because they provide more information than a limited number of analogue plots in one dimension. Contour plots of amplitude and phase data obtained from more complete two-dimensional measurements precisely and accurately locate sources of problems in the range reflector, with phase contour plots being more useful as diagnostic tools.     

A flip-chip packaged coplanar 94 GHz amplifier module with efficient suppression of parasitic substrate effects

A flip-chip mounted W-band amplifier module with more than 15 dB gain between 82 and 105 GHz has been developed, based on a 0.15 /spl mu/m GaAs PHEMT technology. To predict the influence of the flip-chip transition, an equivalent circuit model of the flip-chip interconnects was developed. Lossy silicon (n-Si) flip-chip carriers were used to successfully minimize parasitic substrate modes and feed back effects. The flip-chip assembled coplanar 94 GHz amplifier MMIC was packaged in a WR-10 waveguide mount, using CPW-to-waveguide transitions realized on quartz substrates.     

A feedback model of millimeter wave harmonic oscillators and its application

In this paper a feedback model of second harmonic oscillators is developed. By using describing functions of nonlinearity of active devices, the performances of second harmonic oscillators are studied. Frequency dependence of I–V characteristics of active element are taken into account. The ratio of maximum output power of second harmonic to fundamental is given. The maximum harmonic locking bandwidth of injected harmonic oscillator is derived. The theoretical prediction is compared with experimental results.     

平面超材料对曲折线慢波结构行波管效率改善和杂模抑制的影响

针对U型曲折线慢波结构带状注行波管杂模抑制和互作用效率提高等面临的挑战,提出了一种开口菱形超材料结构。在综合考虑电路单元谐振性能、与U型曲折线慢波结构之间的协调配合以及电路实现可行性和结构简单等因素,通过电路设计和数值模拟优化等具体措施相结合,探讨这种超材料对增强注波互作用表面电场和抑制电路振荡的效果。在Ka波段优化的结果表明,这种超材料在抑制杂波和改善注波互作用效率方面效果明显,对此类行波管稳定性提高具有重要意义。     

毫米波合成孔径雷达的发展及其应用

分析了毫米波SAR高分辨成像的基本原理,阐述了毫米波SAR的优点,并结合目前国际上典型的毫米波SAR系统,综述了毫米波SAR技术与系统的发展状况,讨论了毫米波SAR的应用前景、存在的问题以及未来的发展趋势.     

毫米波波束管理的设计与研究

毫米波是第五代移动通信系统的重要通信技术,因其频谱特性可以利用大带宽承载大量信息,有效提升系统的吞吐量。高频段毫米波传输具有高损耗性,且受环境影响较大,为了支持非视距和移动性,必须支持准确且实时的波束跟踪以确保信号传输质量。波束管理的目的是使得基站与终端之间发送与接收波束对准以提高链路的性能。文中根据3GPP协议规范设计了波束管理方案,包括以下几方面的内容:波束扫描、波束测量、波束上报、波束指示、波束失败恢复。