Millimeter Wave and Terahertz Communications: Feasibility and Challenges

In this paper, the challenges with and motivations for developing millimeter wave and terahertz communications are described. A high-bye candidate architecture is presented, and use cases highlighting the potential applicability of high-frequency links are discussed. Mobility challenges at these higher frequencies are also discussed. Difficulties that arise as a result of high carrier frequencies and higher path loss can be overcome by practical, higher-gain antennas that have the added benefit of reducing intercell interference. Simulation methodology and results are given. The results show that millimeter wave coverage is possible in large, outdoor spaces, and only a reasonable number of base stations are needed. Network throughput can exceed 25 Gbit/s, and cell-edge user throuqhput can reach aDoroximatelv 100 Mbit/s.

Cell-type continuous electromagnetic radiation system generating millimeter waves for active denial system applications

The cell-type continuous electromagnetic radiation system is a demonstration device capable of generating high-power millimeter electromagnetic waves of a specific wavelength and observing their effects on living organisms.It irradiates a biological sample placed in a 30×30×50 cm^(3)cell with electromagnetic waves in the 3.15-mm-wavelength region(with an output of≥1 W)and analyzes the temperature change of the sample.A vacuum electronic device-based coupled-cavity backward-wave oscillator converts the electron energy of the electron beam into radiofrequency(RF)energy and radiates it to the target through an antenna,increasing the temperature through the absorption of RF energy in the skin.The system causes pain and ultimately reduces combat power.A cell-type continuous electromagnetic radiation system consisting of four parts—an electromagnetic-wave generator,a highvoltage power supply,a test cell,and a system controller—generates an RF signal of≥1 W in a continuous waveform at a 95-GHz center frequency,as well as a chemical solution with a dielectric constant similar to that of the skin of a living organism.An increase of 5°C lasting approximately 10 s was confirmed through an experiment.

CAD OF MILLIMETER WAVE OSCILLATORS WITH THE FDHB TECHNIQUE

In this paper the modelling, analysis and optimization of millimeter wave oscillatorsare investigated by using the a frequency-domain harmonic balance technique (FDHB), where theexternal-circuit impedances looking outside from the active device are calculated with a combinedtechnique of modes expansion, Galerkin, and collocation methods. The optimization results arein agreement with the experimental ones, which show the reliability of the presented model andoptimization.

High-Resolution Broadband Millimeter-Wave Astrophysical Spectrometer with Triple Product Acousto-Optical Processor

An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as one of the potential observational infrastructures where the acousto-optical spectrometer can be successfully used. A summary on the study of molecular gas in relatively old (age > 10 Myr) disks around main sequence stars is provided. We have identified this as one of the science cases in which the proposed processor can have a big impact. Then we put forward triple product acousto-optical processor is able to realize algorithm of the space-and-time integrating, which is desirable for a wideband spectrum analysis of radio-wave signals with an improved resolution providing the resolution power of about 105 - 106. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this algorithm is based on exploiting the chirp Z-transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of developing the triple product acousto-optical processor in frames of the astrophysical instrumentation is shortly discussed.

Large-signal characterizations of DDR IMPATT devices based on group Ⅲ–Ⅴ semiconductors at millimeter-wave and terahertz frequencies

Large-signal （L-S） characterizations of double-drift region （DDR） impact avalanche transit time （IM- PATT） devices based on group III-V semiconductors such as wurtzite （Wz） GaN, GaAs and InP have been carried out at both millimeter-wave （mm-wave） and terahertz （THz） frequency bands. A L-S simulation technique based on a non-sinusoidal voltage excitation （NSVE） model developed by the authors has been used to obtain the high frequency properties of the above mentioned devices. The effect of band-to-band tunneling on the L-S properties of the device at different mm-wave and THz frequencies are also investigated. Similar studies are also carried out for DDR IMPATTs based on the most popular semiconductor material, i.e. Si, for the sake of comparison. A compara- tive study of the devices based on conventional semiconductor materials （i.e. GaAs, InP and Si） with those based on Wz-GaN shows significantly better performance capabilities of the latter at both mm-wave and THz frequencies.

Potentiality of semiconducting diamond as the base material of millimeter-wave and terahertz IMPATT devices

An attempt is made in this paper to explore the potentiality of semiconducting type-IIb diamond as the base material of double-drift region（DDR） impact avalanche transit time（IMPATT） devices operating at both millimetre-wave（mm-wave） and terahertz（THz） frequencies. A rigorous large-signal（L-S） simulation based on the non-sinusoidal voltage excitation（NSVE） model developed earlier by the authors is used in this study. At first,a simulation study based on avalanche response time reveals that the upper cut-off frequency for DDR diamond IMPATTs is 1.5 THz, while the same for conventional DDR Si IMPATTs is much smaller, i.e. 0.5 THz. The L-S simulationresultsshowthattheDDRdiamondIMPATTdevicedeliversapeakRFpowerof7.79Wwithan18.17%conversion efficiency at 94 GHz; while at 1.5 THz, the peak power output and conversion efficiency decrease to6.19mWand8.17%respectively,taking50%voltagemodulation.AcomparativestudyofDDRIMPATTsbasedon diamond and Si shows that the former excels over the later as regards high frequency and high power performance at both mm-wave and THz frequency bands. The effect of band to band tunneling on the L-S properties of DDR diamond and Si IMPATTs has also been studied at different mm-wave and THz frequencies.

Large-signal characterization of DDR silicon IMPATTs operating in millimeter-wave and terahertz regime

The authors have carried out the large-signal characterization ofsilicon-based double-drift region （DDR） impact avalanche transit time （IMPATT） devices designed to operate up to 0.5 THz using a large-signal simulation method developed by the authors based on non-sinusoidal voltage excitation. The effect of band-to-band tunneling as well as parasitic series resistance on the large-signal properties of DDR Si IMPATTs have also been studied at different mm-wave and THz frequencies. Large-signal simulation results show that DDR Si IMPATT is capable of delivering peak RF power of 633.69 mW with 7.95% conversion efficiency at 94 GHz for 50% voltage modulation, whereas peak RF power output and efficiency fall to 81.08 mW and 2.01% respectively at 0.5 THz for same voltage modulation. The simulation results are compared with the experimental results and are found to be in close agreement.

太周探测:从60年代四大天文发现说起(下)

人类的探索欲望及数千年来的不断积累促成了20世纪60年代的四大天文发现,而大气层对天文观测的一些根本性限制促使人们在20世纪冲出地球进入太空。在宽广的波段进行天文观测有着极为苛刻的要求,新猜想和模型的提出也要求进行新的验证,这些都促进了观测设备及器件的性能趋于极致。本文旨在对此进行简要的回顾分析并列举一些典型实例,侧重考察其探测波段、主镜或天线的口径、探测仪器及所用器件的类型和性能等,以便进行纵向和横向的比较,温故而思新。

元素成像技术在安检领域的研究进展

元素成像作为一种快速、直观的无损检测技术,在核工业、航空航天、新能源、地质、考古、先进制造等多个领域得到广泛应用。其中X射线凭借较强穿透物体的能力,在安检领域已得到广泛应用。太赫兹和毫米波凭借对人体无接触、几乎无损害的特点,在安检领域崭露头角。对这三种元素成像技术的原理、成像过程、安检图像数据集和近几年的图像增强和智能处理技术进行了总结和归纳。未来,随着应用的深入发掘和技术的不断进步,元素成像和人工智能的结合必将进一步深入,不断提高分析的质量和速度,从而以高水平安全保障社会经济的高质量发展。

毫米波功率应用研究进展(特邀)

微波功率应用是一种直接利用微波的功率和能量与物质互作用的应用。近年来,随着毫米波功率源技术的发展,微波功率应用逐渐向毫米波频段发展。由于毫米波波长较短,在功率应用中展现出诸多独特特性,并发展出一系列独特应用。本文对毫米波在物理科学、材料科学、生物医学等领域的研究工作进行了评述,主要包括聚变等离子体加热与诊断、材料加工与分析、生物效应应用等,对目前研究和发展中的主要瓶颈问题进行了介绍,并对未来发展进行了展望。

太赫兹真空器件中超深金属慢波结构的微加工技术

太赫兹真空电子器件物理结构尺寸变化随着波长的减小而减小,对微小结构的尺寸精度与表面粗糙度要求也大大增加。随着器件频率进入到太赫兹频段,慢波结构的深度达到几十微米或者百微米量级,加工的难点主要有:材料为金属,结构超深,表面粗糙度要求达到几十纳米量级,微电铸后金属含氧量极小,结构密度大不漏气,经得起后续近千摄氏度的高温处理工艺等。文章介绍了太赫兹频段下器件慢波结构的加工方式,着重讨论利用深反应离子刻蚀(DRIE)技术和紫外−光刻、电铸(UV-LIGA)技术加工超深金属慢波结构的技术和和特点,并介绍了本实验室利用UV-LIGA加工折叠波导的研究进展。

太赫兹相控阵系统设计研究进展

太赫兹相控阵系统作为未来通信和雷达技术的核心支柱,在6G通信、卫星通信和超低延迟应用中具有广阔前景。本文综述了太赫兹相控阵系统的主要架构,包括中频移相、本振移相、基带移相和射频移相等方案,并分析了其在不同应用场景中的优缺点与技术挑战。特别关注基于CMOS工艺的太赫兹相控阵系统以及太赫兹相控阵收发器的研究进展,涵盖了从W波段到超过0.5 THz的设计突破。这些新兴技术为高频相控阵系统提供了新的设计思路,有望在未来超高速通信和低延迟应用中发挥关键作用。

Tunable magneto-optical polarization device for terahertz waves based on InSb and its plasmonic structure

The nonreciprocal circular dichroism and Faraday rotation effect for terahertz(THz) waves in longitudinally magnetized InSb were investigated by theoretical and experimental studies in the THz regime, which indicated its ability for a THz circularly polarized isolator, THz circular polarizer, tunable polarization converter, and polarization modulator by manipulation of different magnetic fields. Furthermore, we demonstrated the InSb plasmonics based on its magneto-optical effects combined with artificial microstructure. We found the magnetooptical enhancement mechanisms in this magneto-plasmonic structure, achieving broadband near-perfect orthogonal linear polarization conversion modulated by the weak magnetic field in an experiment with an extinction ratio of 33 dB. Moreover, the magneto-optical modulation with an amplitude modulation depth of 95.8% can be achieved by this device under a weak magnetic field of 150 mT. InSb and its magneto-plasmonic device have broad potential for a THz isolator, magneto-optical modulator, and polarization convertor in THz application systems.

微波毫米波与太赫兹噪声源发展现状

微波毫米波与太赫兹噪声源主要用于产生噪声信号,是噪声系数测试系统的核心组成部分。本文对近年来国内外噪声源的发展情况进行总结,将现有的噪声源归纳为基于数字和模拟电路技术、基于固态二极管技术、基于场效应管技术、基于黑体和热电阻技术、基于光电融合技术共5类噪声源,并对这5类噪声源的主要技术特点进行了分析,同时对各类型噪声源的国内外研究现状进行了对比,并对其应用前景和发展趋势进行了展望。

基于专利数据的全球6G天线关键技术创新态势与我国发展对策研究

[目的]本研究基于专利数据分析全球6G天线技术的发展趋势以及我国在该领域的现状,为企事业单位的技术创新和产业研究提供决策支持。[方法]通过统计分析了6G天线技术相关申请的申请量趋势、区域分布及主要申请人,并梳理了四个主要分支超大规模天线技术、毫米波与太赫兹天线、智能超表面技术和轨道角动量的专利技术演进路线。[结论]我国在6G专利申请量上占据领先优势。研究建议,聚焦技术前沿,加强核心技术的攻关与专利布局;注重人才引培,加强国际交流合作;优化技术发展生态,加强产业标准建设。

Carrier suppression in quadruple frequency modulation by cascaded optical external modulators for millimeter-wave generation

The optical carrier suppression in optical quadruple frequency modulation by cascaded external modulators is investigated theoretically and experimentally. Theoretical analysis demonstrates that the optical carrier suppression ratio is related with not only the initial phase difference of electrical signals applied on the two modulators, but also the optical phase shift between the two modulators. The maximum suppression ratio can be achieved when the total phase difference is equal to nπ＋π/2 （n = 1, 2,…）, which is verified by experiments. By properly controlling the total phase shift, 40-GHz millimeter-wave is generated by using a 10-GHz radio frequency （RF） source and the modulators.

硅基毫米波太赫兹倍频器研究进展

硅基集成毫米波太赫兹源依靠高集成度、低成本以及与数字集成电路兼容的优势,成为了下一代6 G高速通讯、高精度态势感知雷达和超高分辨率成像等毫米波太赫兹应用的一大重要支撑。对其中的关键非线性电路倍频器的国内外研究进展进行了调研和总结,具体包括对硅基毫米波太赫兹倍频器的拓扑分类和适用场景进行了详细的梳理。同时,对近几年应用于优化谐波产生的晶体管非线性理论的研究进行了列举。最后,对硅基毫米波太赫兹倍频器研究的未来做出了展望,为倍频器的相关研究者们梳理了清晰的研究路线。

Generation of millimeter-wave sub-carrier optical pulse by using cascaded all-pass cavities

A novel scheme is proposed to transform an ultra-short optical pulse to a millimeter-wave frequencymodulated pulse by using the cascaded all-pass cavities （APCs）. The envelope waveform of the generated pulse train is calculated, showing effective improvement by APC cascading. The extinction ratio is analyzed with different input pulses, different cavity reflectivities, and different cascading numbers. It is shown that the cascading does not introduce much effect on the extinction ratio. Two designs by using Gires-Tournois cavity and waveguide ring resonators are proposed to realize the cascaded APC.

Simulation of thermal processes in metamaterial millimeter-wave to infrared converter for millimeter-wave imager

The main characteristics of millimeter-wave(MM-wave)image detector were simulated by means of accurate numerical modeling of thermophysical processes in a metamaterial MM-to-IR converter.The converter represents a multilayer structure consisting of an ultra thin resonant metamaterial absorber and a perfect emissive layer.The absorber consists of a dielectric self-supporting film that is metallized from both sides.A micropattern is fabricated from one side.Resonant absorption of the MM waves induces the converter heating that yields enhancement of IR emission from the emissive layer.IR emission is detected by IR camera.In this contribution an accurate numerical model for simulation of the thermal processes in the converter structure was created by using COMSOL Multiphysics software.The simulation results are in a good agreement with experimental results that validates the model.The simulation shows that the real-time operation is provided for the converter thickness less than 3µm and time response can be improved by decreasing of the converter thickness.The energy conversion efficiency of MM waves into IR radiation is over 80%.The converter temperature increase is a linear function of a MM-wave radiation power within three orders of the dynamic range.The blooming effect and ways of its reducing are also discussed.The model allows us to choose the ways of converter structure optimization and improvement of image detector parameters.

毫米波人体安检仪伺服系统设计与控制

人体安检仪基于毫米波全息成像技术,采用高集成度毫米波收发阵列配合双面联动机械扫描的方式实现对被检查对象的全身快速扫描成像。在此基础上,开展了毫米波人体安检仪伺服系统设计和控制策略研究。该系统可接受软件分系统的命令、完成系统扫描所需运动机构的驱动和控制、提供扫描同步脉冲信号,实现系统配电、安全联锁、声光报警等功能。同时,基于Profinet工业以太网的现场总线通信协议,通过Profinet现场总线,实现了对伺服电机的PLC控制。