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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • Schottky diodes
  • frequency multipliers
  • submillimeter-wave technology
  • terahertz technology.
  • Submillimeter-wave sources
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • California Institute of Technology
201 条数据
?? 中文（中国） ▾

  • [IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Analytical Investigation of Non-Coherent Mutual FMCW Radar Interference

    摘要： Radar sensors are increasingly utilized in today’s cars. This inevitably leads to increased mutual sensor interference and thus a performance decrease, potentially resulting in impairments caused major safety risks. Understanding signal by interference accurately helps to devise signal processing schemes to combat said performance degradation. For the frequency modulated continuous wave (FMCW) radars prevalent in automotive applications, it has been shown that so-called non-coherent interference occurs frequently and results in an increase of the noise ?oor. In this work we investigate the impact of interference analytically by focusing on its detailed description. We show, among others, that the spectrum of the typical interference signal has a linear phase and a magnitude that is strongly ?uctuating with the phase parameters of the time domain interference signal. Analytical results are veri?ed by simulation, highlighting the dependence on the speci?c phase terms that cause strong deviations from spectral whiteness.

    关键词： automotive systems,radar signal processing,radiofrequency interference,millimeter wave radar

    更新于2025-09-09 09:28:46

  • Spatio-Temporal Impact of Hand and Body Blockage for Millimeter-Wave User Equipment Design at 28 GHz

    摘要： The recently proposed channel model by the Third Generation Partnership Project for fifth generation New Radio (5G-NR) systems at millimeter-wave carrier frequencies in TR38.901 provides a good starting point for understanding the impact of propagation, material penetration, and blockage in cellular access systems. With this backdrop, the focus of this article is on hand and body blockage which have a significant bearing on user equipment (UE) design and in the practical viability of millimeter-wave systems. Building on TR38.901, we first study hand and body blockage loss with experiments using a 28 GHz experimental prototype that emulates a 5G base station and a form-factor UE. These measurement estimates show that while blockage losses can be substantial, they are significantly lower than the agreed model in TR38.901. We then study the implications of these revised estimates on spherical coverage with the UE. For this, we consider two form-factor UE designs: a face design and an edge design. Our studies show that while both designs are generally comparable in terms of spherical coverage, practical design considerations favor the edge design over the face design. We finally report on the timescales at which blockage events occur and show that given the symbol periods in 5G-NR, it is possible to implement mitigation strategies to overcome blockage (e.g., switch beams at the UE from a blocked path to an unblocked path).

    关键词： body blockage,hand blockage,user equipment design,beam switching,spherical coverage,millimeter-wave,5G

    更新于2025-09-09 09:28:46

  • Millimeter-Wave Channel Measurement and Modeling: A NIST Perspective

    摘要： The exponential increase in wireless data transmission from smartphones has led to the saturation of the sub-6-GHz bands — where cellular networks have operated to date — forcing providers to migrate to the millimeter-wave (mmWave) regime for 5G. Although available channel bandwidths will grow from tens of megahertz to several gigahertz, propagation loss will be substantially higher. To compensate the link budget, phased array antennas with 20 dBi–40-dBi gain will be employed at the base and mobile stations. Since beamwidth is inversely proportional to gain, the resultant pencilbeams will be only 3°–15° wide and thus must be electronically steered to ensure that they are aligned between the stations. The high directionality of 5G systems will fundamentally change channel propagation models and channel sounding systems and techniques used to measure the model properties. The National Institute of Standards and Technology is on the forefront of defining that change. In this article, we provide an overview of mmWave channel sounding through three types of systems: switched array, virtual array, and phased array, at 28 GHz, 60 GHz, and 83 GHz. In addition, we describe how mmWave channel models, for path loss, dispersion, multipath tracking, Doppler spread, and blockage, differ from sub-6-GHz models, substantiated by some of our most recent results.

    关键词： Doppler spread,path loss,millimeter-wave,dispersion,5G,multipath tracking,blockage,channel sounding,channel modeling

    更新于2025-09-09 09:28:46

  • [IEEE 2018 IEEE International Conference on Communications (ICC 2018) - Kansas City, MO (2018.5.20-2018.5.24)] 2018 IEEE International Conference on Communications (ICC) - Uplink Interference Analysis with RF Switching for Lens-Based Millimeter-Wave Systems

    摘要： In this paper, we take a fundamental look at the interference characteristics of a lens–based millimeter–wave multiuser multiple–input multiple–output system. We consider a hybrid architecture, implemented via a bank of radio–frequency (RF) switches which perform beam selection followed by low–complexity uplink maximum–ratio combining at baseband. Considering a Rotman lens antenna array in line–of–sight propagation, we derive tight analytical expressions for the average (expected) interference power of an arbitrary user terminal, with and without the presence of RF switching. Our mathematical expressions show that without RF switching, the Rotman lens losses its bene?ts and collapses to a conventional uniform linear array. Numerical results demonstrate that the expected interference power of a given terminal decreases signi?cantly with RF switching, due to the beam selection process separating multiple uplink direction–of–arrivals (DoAs). This is in contrast to the case when there is no RF switching, which relaxes the beam selection constraints and thus allows very similar DoAs. Overall, the results in this paper emphasize the necessity of RF switching in order to obtain superior performance with a Rotman lens array, over conventional phased arrays.

    关键词： multiuser multiple–input multiple–output,Rotman lens,RF switching,interference power,millimeter–wave

    更新于2025-09-09 09:28:46

  • Hybrid Beamforming for Millimeter Wave Massive Multiuser MIMO Systems using Regularized Channel Diagonalization

    摘要： This letter presents a novel hybrid analog-digital beamforming design for massive multiuser MIMO downlink transmission in sparse millimeter wave (mm-wave) channels. The proposed hybrid regularized channel diagolnalization (HRCD) scheme combines analog (RF) phase-only beamforming with linear digital (baseband) precoding based on regularized channel diagonalization. Being a hybrid beamforming design utilizing simple non-iterative processing, HRCD provides a low complexity solution that is capable of outperforming several other hybrid schemes including those based on block diagonalization, as shown through simulations. Furthermore, it is also shown that the performance remains strong even with the use of ?nite-resolution phase shifters.

    关键词： Hybrid beamforming,massive multiuser MIMO,millimeter wave

    更新于2025-09-09 09:28:46

  • Miniaturized Wideband Coupler for 60-GHz Band in 65-nm CMOS Technology

    摘要： A compact and wideband coupler for the 60-GHz frequency band applications using 65-nm CMOS technology is presented. By meandering the coupled line, a miniaturized coupler can be obtained. The proposed coupler achieves a measured insertion loss between the input port and the through port (S21) of 6.3 dB and between the input port and the coupled port (S31) of 5.6 dB at 60 GHz. The measured amplitude imbalance and phase difference are 0.75 dB and 92°, respectively, at 60 GHz. Overall, the proposed coupler can achieve a measured amplitude imbalance of <1 dB, phase imbalance of <4°, return loss, and isolation better than 13 and 20 dB, respectively, from 50 to 67 GHz. In addition, the proposed coupler occupies a core area of only 156 μm × 157 μm (0.024 mm2).

    关键词： millimeter wave,60 GHz,coupler

    更新于2025-09-09 09:28:46

  • Synthesis Technique for Low-Loss mm-Wave T/R Combiners for TDD Front-Ends

    摘要： A time-division duplex (TDD) transmit/receive (T/R) millimeter-wave (mm-wave) front-end comprises a power amplifier (PA), a low-noise amplifier (LNA), an antenna switch, and appropriate passive matching and combining networks. In this paper, a synthesis methodology is proposed that minimizes the overall losses by combining the PA output and the LNA input matching networks together with the T/R switch into one network. The technique improves mm-wave transceiver performance in terms of PA efficiency and LNA noise figure. The proposed T/R combiner can achieve high linearity and can handle large PA output voltage swings. The architecture can be implemented in any process which provides high integration capability. A Ka-band implementation is demonstrated using 45 nm CMOS silicon-on-insulator that includes a high power, four-stack-based PA and an inductively source-degenerated cascode-based LNA. Within the front-end, the PA achieves saturated output power of 23.6 dBm with peak power added efficiency of 28%, while the LNA achieves NF of 3.2 dB. The overall chip area is 0.54 mm2, including pads.

    关键词： transmit/receive (T/R) switch,low-noise amplifier (LNA),power amplifier (PA),5G transmitters,stacked power amplifier,silicon-on-insulator (SOI),time-division duplex (TDD),CMOS,millimeter-wave (mm-wave),Ka-band

    更新于2025-09-04 15:30:14

  • [IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Extraction of Relative Permittivity from Measured Reflection Coefficient of Dielectric Materials in the Frequency Range 207 – 247 GHz

    摘要： This work describes the use of millimetre wave technology to extract the dielectric constants of different types of dielectric materials. The extraction of the dielectric materials is based on measurements (i.e., monostatic measurements) of the reflection coefficient for various dielectric materials. The measurements are done by utilizing a frequency modulated continuous wave radar with a dielectric lens antenna. The investigated materials are broadly utilized as a part of our everyday life. The fundamental dielectric materials outcomes are done accompanying materials: Polytetrafluoroethylene (PTFE), mainly Teflon, nylon, and. The measurements are done in the frequency range from 207 GHz to 247 GHz.

    关键词： reflection coefficient,material characteristics,corner reflector,millimeter wave length,dielectric materials,permittivity,measurement,lens antenna

    更新于2025-09-04 15:30:14

  • ELECTROMAGNETIC SIGNATURES OF HUMAN SKIN IN THE MILLIMETER WAVE BAND 80-100 GHZ

    摘要： Due to changes in global security requirements attention is turning to new means by which anomalies on the human body might be identi?ed. For security screening systems operating in the millimeter wave band anomalies can be identi?ed by measuring the emissivities of subjects. As the interaction of millimeter waves with the human body is only a fraction of a millimeter into the skin and clothing has a small, but known e?ect, precise measurement of the emission and re?ection of this radiation will allow comparisons with the norm for that region of the body and person category. A technique to measure the human skin emissivity in vivo over the frequency band 80 GHz to 100 GHz is developed and described. The mean emissivity values of the skin of a sample of 60 healthy participants (36 males and 24 females) measured using a 90 GHz calibrated radiometer were found to range from 0.17±0.005 to 0.68±0.005. The lower values of emissivity are a result of measuring particularly thin skin on the inner wrist, volar side of the forearm, and back of hand, whereas higher values of emissivity are results of measuring thick skin on the outer wrist, dorsal surface of the forearm, and palm of hand. The mean di?erences in the emissivity between Asian and European male participants were calculated to be in the range of 0.04 to 0.11 over all measurement locations. Experimental measurements of the emissivity for male and female participants having normal and high body mass index indicate that the mean di?erences in the emissivity are in the range of 0.05 to 0.15 for all measurement locations. These results show the quantitative variations in the skin emissivity between locations, gender, and individuals. The mean di?erences in the emissivity values between dry and wet skin on the palm of hand and back of hand regions were found to be 0.143 and 0.066 respectively. These results con?rm that radiometry can, as a non-contact method, identify surfaces attached to the human skin in tens of seconds. These results indicate a route to machine anomaly detection that may increase the through-put speed, the detection probabilities and reduce the false alarm rates in security screening portals.

    关键词： radiometry,security screening,emissivity,human skin,millimeter wave

    更新于2025-09-04 15:30:14

  • AIP Conference Proceedings [Author(s) INTERNATIONAL CONFERENCE ON INVENTIVE MATERIAL SCIENCE APPLICATIONS: ICIMA-2018 - Tamil Nadu, India (27–28 September 2018)] - An optical millimeter wave generation using carrier suppression modulation scheme based on frequency 12 tupling lithium niobate mach zehnder modulator without an optical filter

    摘要： This article presents a novel method for the generation of optical millimeter wave (mmw) from a microwave signal using a single Lithium Niobate Mach Zehnder Modulator (LiNbO3 MZM). The carrier suppression scheme supports the experimental setup for achieving 12-tupling frequency by suppressing the sidebands of wave signal by fixing the modulation and bias voltage as 10V. The absence of optical filter leads to fast tuning of required frequency by the modulator which helps to achieve 12 tupling frequencies effectively. The pseudorandom bit sequence in the rate of 50 Gbps is transmitted through a single mode optical fiber for a distance of 60 km. The experiment achieves a high data rate, less complexity and better performance in the absence of an optical filter and an amplifier when compared to other conventional methods. The proposed method performs error free transmission along the fiber of length 60 km and the efficiency of the generated mmw is analyzed by using optical spectrum, RF spectrum and eye diagram visualizers. The quality factor is also included in the paper using Bit Error Rate (BER) analyzer to prove that the energy loss is negligible in the setup.

    关键词： Millimeter wave generation Radio over Fiber,Optical Spectrum,Frequency 12-tupling,Lithium Niobate Mach-Zehnder modulator,Optical carrier suppression

    更新于2025-09-04 15:30:14