Keysight（是德科技）阻抗测量附件选型指南

Keysight（是德科技）PNA和ENA网络分析仪选型指南

PNA and ENA Network Analyzers    PNA Network Analyzers    ENA Network Analyzers    PNA Network Analyzers,ENA Network Analyzers Product accessories   

KEYSIGHT  -  ENA NETWORK ANALYZERS,ECAL（电子校准）模块,ECAL (ELECTRONIC CALIBRATION) MODULES,ECAL MODULE,4-PORT ECAL MODULE,PNA网络分析仪,4-PORT NETWORK ANALYZERS,ENA网络分析仪,NETWORK ANALYZERS,PNA NETWORK ANALYZERS,4-PORT NETWORK ANALYZERS,网络分析仪,4-PORT 4-PORT ECAL MODULE,E8364B-084,PNA,E8364B-082,E8257D-UNX,N52300-082,PNA-X,N52300-080,E8362B-0821,3,N4693A,85092C,N52300-245,PNA-L,N52300-125,N52300-246,E8364A-081,E8364A-080,E507171C,E8361A,PNA-L SERIES,N52300-525,E8361A-016,N4431B,E8361A-014,E8361A-UNL,E8361A-010,N5181A-503,N5242A,N5181A-506,N5230A,N5181A,85093C,E8362A-016,N4694A,E4428C-UNB,E4428C,E8362A-010,E8663B,E8364B,E8257D-540,E8361A-083,E8361A-084,E8361A-081,E8364A-083,E8361A-082,E8362B-014,E8362B-UNL,E5071C,E8361A-080,ENA,E8363B-014,E8363A-010,E8362A-083,N52300-025,N52300-146,E8362A-081,N4691B,E8362A-080,N52300-145,E8363B,E8364A-010,E8257D-550,N52300-425,E8257D-1EA,N52300-225,E8362B-084,N4433A,E8364A-016,E5071C-480,E8663B-509,E5071C-240,E5071C-285,E5071C-440,E5071C-485,E5071C-245,N4692A,85091C,E8257D,E8364B-014,E8363B-084,E8363B-082,E8362B,E8364B-UNL,E5071C-280,N52310-010,PNA SERIES,E4428C-503,E5071C-445,E8257D-567,E4428C-506,ENA SERIES,E8257D-520,E8663B-503

【选型】Keysight（是德科技）LCR表&阻抗分析仪&测试夹具和附件选型指南（英文）

Impedance Measurements Product Introduction    Impedance Analyzers    Network Analyzer    LCR Meters    Test Fixtures and Accessories   

KEYSIGHT  -  CAPACITANCE METER,LCR METER,电容表,NETWORK ANALYZER,EXTERNAL BIAS ADAPTER,PRECISION LCR METER,MAGNETIC TEST FIXTURES,测试夹具,CLIP LEADS,LF-RF NETWORK ANALYZER,射频网络分析仪,EXTERNAL DC BIAS FIXTURES,网络分析仪,DIELECTRIC TEST FIXTURE,精密LCR表,HIGH TEMPERATURE COMPONENT TEST FIXTURE,TEST FIXTURE,IMPEDANCE ANALYZER,PARALLEL-ELECTRODE SMD TEST FIXTURE,IMPEDANCE ANALYZERS,RF SMD/CHIP COMPONENTS,LCR METERS,TEST LEADS,IMPEDANCE PROBE KIT,LIQUID TEST FIXTURE,SMD/CHIP TEST FIXTURE,BOTTOM-ELECTRODE SMD TEST FIXTURE,LCR表,AXIAL & RADIAL TEST FIXTURE,阻抗分析仪,TERMINAL ADAPTER,射频 SMD/片状器件,E5061B-3L3,E5061B-3L4,E5061B-3L5,E4982A,E4990A-120,E4980A,16092A,16034H,16034E,16048H,E4991B,16048G,16034G,16048D,16200B,5950-3000,16197A,16048E,16452A,16454A,42941A,16048A,E4980A-001,E4991B-002,E4980AL,E4981A,16192A,16065C,16196B,E4990A,16196A,16196D,16194A,16196C,E5061B,16089A,16451B,16047E,16065A,16453A,16089C,16198A,16089B,E5061B-005,16334A,16047A,16201A,42942A,工业电子,MATERIAL,消费电子,PRODUCTION APPLICATIONS,IN-CIRCUIT,LCR COMPONENT,MLCC,PDN,汽车电子,通信设备,SEMI-CONDUCTOR

Keysight（是德科技）矢量网络分析仪选型指南（英文）

Physical measurement ecosystem Introduction    VNA Solutions    Vector network analyzers For Active Component    Vector network analyzers For Passive Component    Vector network analyzers For General Purpose and Education    Vector network analyzers For Manufacturing    High-Speed Serial Interconnect Analysis Introduction    Vector network analyzers Installation and Maintenance Introduction    Related Network Analyzer Products and Accessories Introduction    Vector network analyzers Key Performances and Functions Comparison Overview    Vector network analyzers Migration and Upgrades Introudction    Vector network analyzers Related Literature and Web Resources   

KEYSIGHT  -  NETWORK ANALYZER,ECAL MODULES,MOST ADVANCED AND FLEXIBLE VNA,COMPACT 2-PORT USB VNA,网络分析仪器,SWITCHES,MICROWAVE TEST ACCESSORIES,矢量网络分析仪,PHYSICAL LAYER TEST SYSTEM (PLTS),高性能RF VNA,ACTIVE COMPONENT,MEASUREMENT RECEIVER,VECTOR NETWORK ANALYZERS,高性能多端口VNA,COMBINERS,高性能微波矢量网络分析仪,DIELECTRIC PROBE KIT,测量接收器,VECTOR NETWORK ANALYZERS,VNAS,MICROWAVE NETWORK ANALYZER,虚拟网络分析系统,HIGH PERFORMANCE PASSIVE DEVICES,LOW-COST RF VNA,USB VECTOR NETWORK ANALYZER,全2端口VNA,MILLIMETER-WAVE SYSTEM,MULTIPORT TEST SET,天线接收机,HIGH PERFORMANCE MICROWAVE VNA,ANTENNA RECEIVER,最先进、最灵活的VNA,ECONOMY MICROWAVE VNA,紧凑型双端口USB VNA,HIGH PERFORMANCE RF VNA,PXI VECTOR NETWORK ANALYZER,HIGH-PERFORMANCE MULTIPORT VNA,ELECTRONIC CALIBRATION MODULES,经济微波VNA,LF-RF VNA,手持分析仪,FULL 2-PORT VNA,FILTERS,NETWORK ANALYZER,微波网络分析仪,TRANSMISSION LINES,FIELDFOX ANALYZER,HANDHELD ANALYZER,PXIE VECTOR NETWORK ANALYZER,CALPOD CALIBRATION-REFRESH MODULES,VECTOR NETWORK ANALYZER,低成本射频VNA,VECTOR NETWORK ANALYZER,BROADBAND SYSTEM,M9371A,PNA,85072A,N5221B,PNA-X,P9373A,N5241B,N9914A,USB VNA,N5225B,PNA-L,N5245B,N5249B,N9950A,E5080A,E5092A,E5072A,M937XA,PXI VNA,N9918A,M9485A,E5061B RF,85541A,U1810B,M9372A,N9951A,M9370A,P9372A,N5290A,N5242B,P937XA,N5234B,N5222B,N522XB,N524XB,E5071C,N9915A,ENA,E5063A,M9375A,E5061B LF,N9952A,N5291A,P9371A,N5231B,N5251A,P9375A,N5247B,N5235B,N5239B,N5227B,S93011A,N9916A,M9374A,P9370A,N5232B,P9374A,N5264B,N9913A,N5224B,N1500A,N5244B,N523XB,E5061B,N9917A,855XXA,M9373A,WIRELESS,DIAGNOSIS SYSTEM,P2P COMMUNICATION,ACTIVE COMPONENTS,CIRCUIT TEST,ADAPTER,INDUCTORS,MICROWAVE S-PARAMETER TEST,TEACHING,HSD COMMUNICATION,AEROSPACE,OSCILLATOR,CATV COMPONENT TEST,WIRELESS INSTALLATION AND MAINTENANCE,DIAGNOSIS,QUALITY COMMUNICATIONS SYSTEMS,INTERFERENCE DETECTION,INDUSTRIAL PROCESS,FREQUENCY DOMAINS,CAL LAB,INTERFERENCE ANALYSIS,AMPLIFIERS,PCB,RF COMPONENT TEST,FIELD USE,FERRITE BEADS REGISTERS,AMPLIFIERS,METROLOGY,MEDICAL PROCESS,BTS BACKHAUL COMMUNICATION,BTS,CABLE,CONNECTOR,RF PASSIVE COMPONENT TEST,CAPACITORS,PIM MEASUREMENTS,MIXER FREQUENCY CONVERTER,ANTENNA MANUFACTURING TEST,LF COMPONENT TEST,RESEARCH,COMPONENT Z EVALUATION,BTS FILTER,FRONT END MODULE,INDUSTRY SCIENCE MEDICAL,RF LABS,RADAR,HIGH-POWER RF COMPONENT TEST,MANUAL TEST OF PASSIVE COMPONENTS,SIGNAL INTEGRITY,ANTENNA,HIGHEST PERFORMANCE PASSIVE COMPONENT ANALYSIS,MILITARY COMMUNICATION,HIGH-REJECTION FILTER TEST,TIME DOMAINS,GROUND STATION,MULTI-SITE (PARALLEL) MANUFAC-TURING TEST,MATERIAL,SATELLITE GROUND STATION,PCB MANUFACTURING TEST,PASSIVE COMPONENT TEST,DEFENSE,PA,SIGNAL INTEGRITY TEST,DIAGNOSIS COMPONENT,FILTER,MIXERS,HANDSET,FREQUENCY CONVERTERS,GENERAL PURPOSE MANUFACTURING TEST,MULTIPORT MODULE TEST,MATERIAL MEASUREMENTS,LNA,EDUCATION INSTITUTIONS

Keysight Technologies（是德科技） E5071C Network Analyzer – 9 kHz to 4.5/6.5/8.5 GHz – 100 kHz to 4.5/6.5/8.5 GHz (with bias tees) – 300 kHz to 14/20 GHz (with bias tees) E5092A Configurable Multiport Test Set

本资料详细介绍了Keysight Technologies的E5071C网络分析仪的配置指南。该分析仪支持9 kHz至20 GHz的频率范围，具备2或4端口S参数测试集、合成射频源、10.4英寸彩色LCD和硬盘驱动器。资料涵盖了标准配置、可选配件、附件和外围设备，包括不同频率范围、端口数量、偏置Tees、时间基、硬盘驱动器、附加功能和附件等。此外，还提供了E5092A可配置多端口测试集的配置指南，包括电缆和适配器、附件和校准认证文档。

KEYSIGHT  -  CONFIGURABLE MULTIPORT TEST SET,网络分析仪器,NETWORK ANALYZER,可配置多端口测试装置,11878A,00902-60004,85092C,87106B,E4413A,00902-60003,85054-60001,U9397C,E9304A-H18,E5071C-TDR,L7104B,E5092A,N4431-60007,85036B,85024A,N4431-60006,85036E,85033-60018,85134F,11853A,85033-60017,85134E,E5071C-460,85033-60016,85134H,85033E-400,85134G,85093C,E5071C-465,85033-60019,85054-60009,E4412A,K11644A,85032F-500,83006A,N1021B,85033-60021,85033-60020,85134D,85134C,11525A,85135F,00910-60002,85052-60036,00910-60001,85052-60035,85052-60034,00910-60003,85052-60033,85052-60032,11852B,N9398C,E5071C-1A7,U9400C,E5071C-2D5,85052D85052-60012,E5092A-A6J,85093-60010,E5071C-480,P11644A,85092C-MOF,E5071C-240,11524A,85033E-300,11512A,E5071C-485,11742A,1CP009A,E5071C-245,N1912A,N9399C,85093-60008,85093-60009,11500E,11500F,E5071C-008,85032-60013,8491A,85032-60015,E5071C-010,85032-60014,85032F,P9402C,85054-60038,N9356B,N1911A,N9356C,E5071C-1CN,85054-60046,E5071C-1CP,85054-60047,8710-1761,8710-1764,85032-60009,E5071C-017,E5071C-810,E5071C-019,85032-20001,85032-60008,E5071C-1CM,85032-60007,E5071C-260,82357B,85033E,85130D,85130C,85130F,E5071C-265,N4690B,N1922A,85033E-200,E5071C-4K5,L7222C,N4432-60003,E5071C-1E5,E5071C-820,87222C,85131C,87104B,85131D,85092C-00A,8493A,85131H,N4433-60003,1250-1750,N4691B,P9404C,N1921A,00909-60020,85054-60025,85054-60026,85027-60007,85092C-00M,85027-60006,Z5623A-B20,85027-60005,85092C-00F,1250-1745,1250-1746,1250-1747,85132F,E5071C-285,85032-60020,N4419AK20,85032-60021,00909-60019,85054-60027,85033E-100,85054-60028,N4433A-XXX,E5071C-280,1250-1743,85054-60029,N9355C,1250-1744,N9355B,85054-60037,85054-60030,85054-60031,85054-60032,E5092A-08C,85032-60017,85032-60016,85,85032-60019,85032-60018,N4432A-XXX,85052C,87405B,87405C,E5092A-1A7,85036-60016,85036-60014,10833A,85036-60015,10833B,85036-60012,10833C,85036-60013,10833D,N6315A,E5071C-A6J,E5071C-UNQ,E3663AC,8482A,85032F-100,E5071C-2K5,P281C,N6314A,85054D,P9400C,E5092A-20C,85134-60001,85092-60008,85092-60009,1181BZ,N4690-60001,N4690-60002,N4690-60003,85093C-XXX,85036-60010,85036-60011,U2004A,85134-60004,85134-60002,85134-60003,85092-60010,N4691-60003,85052-60014,11511A,85052-60013,N4691-60001,11644-20018,N1810UL,85052-60012,N4691-60002,11644-20019,E4417A,11644-20016,11644-20017,11852B-004,85130-60006,N4431B,11644-20021,85052-60009,85052-60008,85052-60007,11644-20020,85052-60006,N1810TL,E4416A,85032F-300,85130-60005,U2002A,U2002H,E5071C,N4432A,X281C,E5071C-790,131E85131F,87415A,E4419B,1250-1475,U2001B,X11644A,U2001A,1CN005A,E5092A-1CP,1250-1472,U2001H,L7106B,E5092A-1CN,E5092A-1CM,N4433A,85033E-500,E5071C-440,E4418B,85131-60012,00896-60006,E5071C-4D5,00896-60007,85032F-200,00896-60008,U2000B,U2000A,1CM015A,N4431B-XXX,U2000H,E5071C-445,K281C

Keysight E5071C ENA网络分析仪

Keysight E5071C ENA网络分析仪是一款高性能RF网络分析仪，具备高动态范围、快速测量速度和低噪声等特点。该设备适用于无线通信、汽车、半导体和医疗等行业，提供高效和灵活的测量解决方案。产品特点包括直观的用户界面、PC连接、内置VBA、多种测量通道和可选的4端口配置。此外，E5071C支持多种硬件和软件升级选项，以满足不同测试需求。

KEYSIGHT  -  NETWORK ANALYZER,HIGH STABILITY TIME BASE,ENA NETWORK ANALYZER,经济型机械校准套件,网络分析仪器,射频电子校准模块,MICROWAVE ELECTRONIC CALIBRATION MODULE,STANDARD MECHANICAL CALIBRATION KIT,RF ELECTRONIC CALIBRATION MODULE,高稳定性时基,测试端口电缆,ENA网络分析仪,REMOVABLE HARD DISK,ECONOMY MECHANICAL CALIBRATION KIT,微波电子校准模块,可移动硬盘,标准机械校准套件,TEST PORT CABLE,E5071C-010,8753 SERIES,85032F,85052D,8753,85092C,E5071C-2D5,N4431B,E5071C-017,N4433A,E5071C-260,E5071C-480,E5071C-240,E5071C-460,E5071C-285,N4419AK20,E5071C-440,E5071C-265,E5071C-485,E5071C-245,E5071C-465,E5071C-4D5,E5071C-280,E5071C-2K5,E5071C-4K5,E5071C-1E5,E5071C,N6314A,E5071C-445,E5071C-008

矢量网络分析仪（VNA）产品培训在线学习课程概述

本资料为Keysight公司提供的Vector Network Analyzer (VNA)产品培训eLearning课程概述。课程旨在提升测量技能，包括VNA的基本理解、测量方法、S参数测量、高增益和高功率设备测量等。课程时长5小时，包含考试，适合无线通信和航空航天/国防行业的硬件设计及软件工程师，尤其适合新或经验丰富的工程师优化VNA在组件、发射器和系统评估与开发中的应用。

KEYSIGHT  -  ELEARNING MODULES,VNA,电子学习模块,矢量网络分析仪,VECTOR NETWORK ANALYZER

Keysight E5071C ENA系列网络分析仪

本指南提供使用Keysight E5071C ENA系列网络分析仪进行快速演示的步骤。包括连接DUT到E5071C，预设系统并启动设置向导，使用VBA配置E5071C，以及进行测量参数设置和校准。指南详细说明了连接DUT、配置测量参数、执行校准和分析测量结果的过程。

KEYSIGHT  -  网络分析仪器,NETWORK ANALYZER,E5071C

矢量网络分析仪技术概述

本文介绍了Keysight公司提供的多种向量网络分析仪（VNA）解决方案，涵盖了从经济型到高端的多种型号，以满足不同应用需求。文章详细介绍了不同型号VNA的性能特点、应用领域和关键功能，包括PNA系列、ENA系列、PXI VNA系列、Streamline系列和FieldFox系列。此外，还介绍了VNA模拟器、有源和无源元件的评估与测试、高速数字互连分析等解决方案。

KEYSIGHT  -  矢量网络分析仪模拟器,HANDHELD MICROWAVE ANALYZERS,VECTOR NETWORK ANALYZER (VNA) SIMULATOR,VECTOR NETWORK ANALYZERS,矢量网络分析仪,HANDHELD RF ANALYZERS,手持式射频分析仪,手持式微波分析仪,S94USBCB,PNA,N5241B,P9377B,872XE,8714B,N9950A,8714C,P5001A,P5025B,M9837A,P5001B,E5080B,M9801A,P5025A,E5080A,N9918B,4194A,P502XA SERIES,N9951A,N5242B,N5230A,P93XXB,N5230C,P937XA,P937XB,8713C,8713B,P5002B,872XC,P5002A,872XD,M983XA,872XA,872XB,P502XB,P502XA,P5026B,M9800A,P5026A,M9803A,E5061B ENA,P5003B,P5027A,P5003A,E5070B,P5027B,E5070A,N9916B,4192A,S94050B,N991XB,S96011B,N991XA,E5080B ENA,N5244B,M9802A,P5028B,P5028A,P5004B,P5004A,S94051B,N9917B,P9373B,N5221B,8753 SERIES,P9373A,N5245B,8719E,P5021A,8719C,8719D,8719A,8719B,PNA-X SERIES,P5021B,P9372A,P9384B,8712ET,N5290A,P9372B,8712ES,N5222B,N524XA,N524XB,P5022B,P5022A,M981XAS,ENA,N9952A,N5291A,P9375B,P9375A,N5247B,8510A,8752B,8752C,8510C,N99XXA,8510B,8752A,N99XXB,P5023A,S93011B,P5023B,N5292A,P9374A,P9374B,P938XB,8751A,N5224B,N523XA,N523XB,P5024B,P5024A,P5000B,P5000A,M9834A,8719ES,8719ET,N5225B,N5249B,M937XA,PXI VNA,P502XB SERIES,M9485A,85541B,N1930XB,S97011B,8753E,3577B,8753C,8753D,8753A,N524X,8753B,N522XB,M9808A,4395A,PXI VNA FAMILY,E5063A,M9375A,8714ET,8714ES,P9371B,P9371A,N5295AX,N5227B,3577A,P9370A,P9382B,P9370B,P93XX,E836XC,E836XB,N522XA,PNA SERIES,N522X,E5063A ENA,P5020B,P5020A,S9X011B,M9371A,PNA-X,N9914B,PNA-L,PNA-L SERIES,M9805A,N52935AX,P5005A,E836XA,P5005B,N992XA,872XET,872XES,M9372A,M9370A,N9915B,P500XB,P500XA,P50XX,M9804A,P5006B,P5006A,E5071C,E5071B,E5071A,8753,P5007A,S95011B,M9807A,8712B,8712C,N5293AX,P5007B,E5062A,M9374A,8753ET,8753ES,N5264B,N9913B,N1500A,P5008B,P5008A,M9806A,M980XA,P50XXA,P50XXB,E5061B,E5061A,4195A,M9373A,ENA SERIES,PNA FAMILY,WIRELESS,医学,CONNECTORS,变频器,雷达场试验,微波S参数测试,MULTI-SITE (PARALLEL) MANUFACTURING TESTS,多端口组件测试,制造试验,MICROWAVE S-PARAMETER TEST,INDUSTRY,WIRELESS POWER TRANSFER ANALYSIS,FRONT-END MODULE,系统测试,AEROSPACE,空中交通管制通信,波束形成器集成电路,CABLES,过滤器,ANTENNAS,CAL LAB,T/R模块,AIR TRAFFIC CONTROL COMMUNICATION,搅拌机,AMPLIFIERS,METROLOGY,卡尔实验室,多站点（并行）制造测试,MEDICAL,RF COMPONENT TESTS,科学,A/D应用,天线,BEAMFORMER IC,PC BOARD (PCB) IMPEDANCE TESTS,计量学,SCIENCE,航空航天,MANUFACTURING TEST,MICROWAVE COMPONENT TESTS,无线,放大器,射频组件测试,前端模块,国防,工业,MULTIPORT COMPONENT TESTS,微波元件测试,无线电能传输分析,SYSTEM TEST,印刷电路板（PCB）阻抗测试,连接器,FILTERS,材料测量,DEFENSE,MIXERS,A/D APPLICATIONS,RADAR FIELD TEST,FREQUENCY CONVERTERS,MATERIAL MEASUREMENTS,T/R MODULES,电缆

N5244B N5245B Keysight 2端口和4端口PNA-X网络分析仪

本资料详细介绍了Keysight公司生产的N5244B和N5245B网络分析仪的技术规格。N5244B覆盖900 Hz至43.5 GHz频段，而N5245B覆盖900 Hz至50.0 GHz频段。资料涵盖了动态范围、系统动态范围、接收器动态范围、测试端口输出和输入、相位噪声测量性能、动态准确性、测量吞吐量等关键性能参数。

KEYSIGHT  -  CALIBRATION KIT,网络分析仪器,校准套件,相位噪声测量应用,NETWORK ANALYZER,PHASE NOISE MEASUREMENT APPLICATION,85056D,S930317B,PNA-X,N4693A,N5245B,N4693D,N5244B,85056A

Keysight N5244B–900 Hz至43.5 GHz N5245B–900 Hz至50.0 GHz 2端口和4端口PNA-X网络分析仪

KEYSIGHT  -  4端口PNA-X网络分析仪,4-PORT PNA-X NETWORK ANALYZER,网络分析仪器,2端口PNA-X网络分析仪,2-PORT PNA-X NETWORK ANALYZER,NETWORK ANALYZER,85056D,N5245BS,N5244BS,S930317B,PNA-X,N4693A,N5245B,N4693D,N5244B,85056A

使用LCR表和阻抗分析仪测量介电常数和磁导率的解决方案应用笔记

本文介绍了使用LCR表和阻抗分析仪测量介电常数和磁导率的方法。文章首先定义了介电常数和磁导率的概念，并详细阐述了平行板法测量介电常数的原理和步骤，包括接触电极法和非接触电极法。接着，文章介绍了使用16451B和16453A测试夹具进行介电常数测量的系统，并提供了详细的操作方法和注意事项。此外，文章还讨论了磁导率的定义和测量方法，以及使用16454A磁材料测试夹具进行磁导率测量的系统。最后，文章提供了测量误差分析和样品测量结果。

KEYSIGHT  -  LCR仪表,IMPEDANCE ANALYZERS,阻抗分析器,LCR METERS

Keysight（是德科技） 2-Port and 4-Port PNA Network Analyzer N5227A 10 MHz to 67 GHz

本资料详细介绍了Keysight N5227A网络分析仪的技术规格和应用。该分析仪支持2端口和4端口配置，频率范围为10 MHz至67 GHz。资料涵盖了系统性能、动态范围、接收器动态范围、测试端口输出和输入、动态精度、群延迟等关键性能指标，并提供了详细的技术参数和典型性能数据。

KEYSIGHT  -  PNA NETWORK ANALYZER,PNA网络分析仪,N5227A

安捷伦8757D标量网络分析仪

KEYSIGHT  -  SCALAR NETWORK ANALYZER,标量网络分析仪,8757D-001,8757D-012,8757D-002,8757D-700,8757D