Understanding RF Experiment 2
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名词辨析,动词辨析,动词短语辨析适用学科英语适用年级高中二年级适用区域陕西西安课时时长(分钟)60知识点各种时态的被动语态,名词辨析,动词辨析,动词短语辨析教学目标掌握选修七 unit 2重点词汇,短语,句型。
同时,训练阅读理解能力和综合语言能力。
教学重点掌握选修七unit2重点词汇,短语,句型。
同时,训练阅读理解能力和综合语言能力。
教学难点训练阅读理解能力和综合语言能力。
教学过程一、复习预习教师引导学生复习上节内容,并引入本节课程内容二、知识讲解本节课主要知识点解析,中高考考点、易错点分析考点/易错点1词汇辨析1. sympathy 同情心,同情; 怜悯一致; 同感; 赞同,慰问; 吊慰习惯用语:come out in sympathy 举行同情罢工, 罢工声援express sympathy for (对...表示)慰问feel sympathy for (=have sympathy for) 同情in sympathy with 同情; 赞成; 和...一致win sympathy of 博得...的同情out of sympathy with 对...不同情; 不赞成; 对...没有同感, 和...不一致feel/have sympathy for… 同情… be in sympathy with… 赞同…seek sympathy from a friend 想得到朋友的同情同义词:commiseration -mercy -pity -sensitivity -tolerance -understanding1) I felt real sympathy. 我由衷地感到同情。
2) Her sympathy became pungent. 她的同情心变得强烈起来。
3) With profound sympathy.4) I felt much sympathy for the blind.5) Her sympathy became pungent. 她的同情心变得强烈起来。
摘要摘要微波光子学是微波技术与光子学相结合的产物。
相比传统技术,微波光子技术具有低损耗、大带宽、抗电磁干扰、体积小以及重量轻等优势。
随着目前信息业务的多样化以及通信频段的提高,传统微波混频技术面临带宽受限、频率可调性差、隔离度低、电磁干扰严重等电子瓶颈,传统电域变频技术逐渐难以满足未来电子系统发展需要。
而微波光子变频技术可以很好的解决这些难题,从而在未来电子系统中具有较大的应用前景,近些年来受到广泛的关注和研究。
本文面向未来电子系统发展需求,针对目前微波光子变频领域存在的技术难题,对低本振频率需求、高变频效率的微波光子变频技术开展具体研究。
本文的基础性工作主要有:首先介绍微波光子变频技术的主要器件,对它们的工作原理进行理论分析。
接着在VPI仿真软件中对常见的三种调制方式,即单边带调制、双边带调制以及抑制载波双边带调制做了仿真分析。
其次介绍了微波光子变频技术的三个关键性指标,即变频增益、噪声系数以及无杂散动态范围。
另外还研究了一些已经被提出的微波光子变频方案,对这些方案进行理论分析以及仿真验证。
在第四章提出了一种基于Sagnac环的本振二次谐波变频方案,该变频方案具有以下几个优点:利用本振二次谐波进行变频,降低了变频系统对本振信号的频率要求;抑制了光载波,可以有效提高变频效率;并且由于RF以及LO信号是利用不同的调制器进行调制,因此尤其适合天线拉远系统。
在实验中利用频率为4GHz的LO信号以及25GHz的RF信号经过上下变频后分别得到33GHz以及17GHz的信号,其中IF-RF隔离度为32.72dB,变频增益为-12.2dB,动态范围为102.1dB∙Hz2/3。
在第五章提出了一种基于DP-DPMZM的本振四次谐波变频方案,该变频方案具有以下几个优点:利用本振四次谐波进行变频,进一步降低了变频系统对本振信号的频率要求;抑制了光载波,可以有效提高变频效率。
在仿真中利用频率为2GHz的LO信号以及30GHz的RF信号经过上下变频后分别得到38GHz以及22GHz的信号,其中IF-RF隔离度为30dB,变频增益为-12dB,动态范围为102.5dB∙Hz2/3。
Experiment 12: AM Signal Demodulation TechniquesPurpose and DiscussionThe purpose of this simulation is to demonstrate the characteristics and operation of an envelope detector, and to provide a comprehension of the stages that a modulated signal is subjected to at the receiver, so that the original transmitted information is recovered.An AM signal, once received by a receiver, is subjected to several stages in thedemodulation process. Figure 12-1 illustrates the final detection and filter stage usinga simple diode detector. Other more complex detectors that use the popular PLL(phase-lock-loop) circuitry allow, together with AGC (automatic gain control)circuitry, modulation indexes of close to one.Because the circuitry involved in the detection process is fixed, a fundamentalrequirement for a signal at the detector's input is that the sidebands are situated on either side of a fixed frequency. This fixed frequency is called the IF or intermediate frequency and is produced by the mixing of a local oscillator frequency with the RF spectrum which has been filtered in the RF stage of the demodulation process. The fixed value of the intermediate frequency is 455 kHz. This IF signal is applied to the input of a highly selective IF amplifier.The local oscillator (LO) frequency in the popular superheterodyne receiver isadjusted through the tuning control to 455 kHz above the RF carrier, f LO = f c + f IF.Why is the LO necessary? Remember that the detector requires the message signal to be frequency translated to either side of a fixed intermediate frequency. Injecting the RF spectrum and the local oscillator frequency through a mixer will produce the sum and difference of the frequencies involved. It is the difference frequencies thatproduce the IF spectrum required. Consider a carrier frequency of 1050 kHz carryinga 5 kHz message signal.The IF filter features steep roll off characteristics which reject all frequencies other than the IF frequency translated spectrum. The output of the filter constitutes the input to the detector.The envelope detector of Figure 12-1 is designed to subject the signal to a half wave rectification process. The RC time constant should be such that the charge time is fast56 Understanding RF Circuits with Multisimand the discharge time is slow. This will ensure that the detector follows theamplitude variations of the envelope. The RC time constant of the envelope detector should be designed such that:Not shown in Figure 12-1 is the AGC circuitry which helps to control the level of the input to the detector.One of the main drawbacks of the envelope detector is the effect of the diode voltage drop Vd. This 0.7 V drop represents a delay between the point where the signalreaches the input and where the capacitor is able to allow the output to react to the input. This ultimately results in power lost because the modulation index is restricted from reaching its optimum level of one. The detector of Figure 12-2 will detectmodulation signals over a range of frequencies with the particular low pass filter portion supporting a cutoff frequency of 2 kHz for purposes of demonstration.PartsResistors: 330 Ω, 620 Ω, 3.3 k Ω, 5.2 k Ω, 15 k Ω, 33 k ΩCapacitors: 2 nF, 4.7 nF, 2.2 nF, 12 nFDiode: 1N4148Ideal OpampsAM ModulatorTest Equipment• OscilloscopeFormulaeRC Time ConstantEquation 12-1RC mf m =12πRC mf m =12πAM Signal Demodulation Techniques57 ProcedureFigure 12-1 Envelope Detector ExampleFigure 12-2 Diode Detector Example1.Connect the circuit components illustrated in Figure 12-1.2.Double-click the Oscilloscope to view its display. Set the time base to 1 ms/Divand Channel A to 10 V/Div. Select Auto triggering and DC coupling.58 Understanding RF Circuits with Multisim3.Double-click the AM Source to change its parameters. Set the carrier amplitude =10 V, the carrier frequency = 100 kHz, the modulation index = 0.6 and themodulation frequency = 800 Hz.4.Start the simulation and measure the frequency of the demodulated waveform andcompare it with its expected value. Record your results in the Data section of this experiment.5.Double-click on the resistor to change its value. Select a 500 kΩ resistor. Run thesimulation again. Draw the waveform associated to a time constant which is toolarge. Next, replace the 500 kΩ resistor with a 10 kΩ resistor. Run the simulation and draw the waveform associated to a time constant which is too small.6.Re-design the detector in order to provide optimum detection for a 500 Hzmodulating signal. Replace the components, re-set the AM Source modulatingfrequency parameter and run the simulation.7.Connect the circuit components illustrated in Figure 12-2. Connect bothOscilloscope channels as shown. Set the time division to 500 µs/Div, Channel Ato 500 mV/Div and Channel B to 5 V/Div. Set the AM Source as indicated inFigure 12-2. Run the simulation. Note your observations.Expected OutcomeFigure 12-3 Output of Envelope Detector at m = 0.6AM Signal Demodulation Techniques59Figure 12-4 Output of Detector Stage of Figure 12-2Data for Experiment 12f m at output of detectorf m expectedWaveform of an RC time constant which is too largeWaveform of an RC time constant which is too smallFrom step 5, re-designed value of R = and C = .Step 6 .60 Understanding RF Circuits with MultisimAdditional ChallengeDouble-click on the AM Source of Figure 12-1 to change its modulation indexparameter to 1. Run the simulation and note the difference in the waveform at the output of the detector. Change the modulation index to 1.4. Run the simulation and note the difference in the waveform at the output of the detector.。
射频电路教学中的理论与工程实践鲍景富;陈瑜【摘要】通过对射频电路教学的特点进行分析,探讨射频电路理论学习与实验的关系。
提出在理论教学中穿插以仿真软件实现的验证实验,以加强学生对理论知识的理解,同时提出将开放式实验引入到射频电路实践教学中。
通过循序渐进的开放式实验,以及针对性的工程实践能力训练,使学生能够将射频电路理论学习与工程实践良好地结合起来,消除理论学习与工程实践的脱节,提高学生的理论水平以及工程实践能力。
%In this paper, we analyses the characteristics of the teaching of the RF circuit and the relationship between the theory and practice. One proposed using simulation software validation experiments in order to enhance students understanding of theoretical knowledge. While we proposed introduce open-ended experiment into the RF circuit practice teaching, through a gradual opening experiment, as well as the ability of targeted training in engineering practice, so that students can study and RF circuit theory and engineering practice. A good combination of theoretical study and engineering practice ean eliminate the gap and improve student's levels of theory and engineering practice ability.【期刊名称】《实验科学与技术》【年(卷),期】2012(010)003【总页数】4页(P121-124)【关键词】验证实验;工程实践;开放式实验;射频电路【作者】鲍景富;陈瑜【作者单位】电子科技大学电子工程学院,成都611731;电子科技大学电子工程学院,成都611731【正文语种】中文【中图分类】G642.4射频电路是一门教学难度较大的课程,原因在于其中有些较难理解的概念和很强的工程实践性。
ISSN 1002-4956 CN11-2034/T实验技术与管理Experimental Technology and Management第38卷第2期2021年2月Vol.38 No.2 Feb. 2021D O I: 10.16791/ki.sjg.2021.02.044基于C ST仿真软件的阻抗匹配设计教学实验赓臻\賡志斌2,刘宇平2(1.杭州电子科技大学电子信息学院,浙江杭州310018;2.新余学院数学与计算机学院,江西新余338000 )摘要:传输线的阻抗匹配是电磁场与微波技术中一个重要的理论,是射频微波电路设计的基础:但相关概念较为抽象,传统教学过程以数学推导为主,学生理解困难。
为了增强学生对阻抗匹配的理解,以微带线阻抗匹配的典型工程应用为案例,将理论分析与电磁仿真相结合,对微带线阻抗匹配网络进行设计,增强学生对传输线阻抗匹配的理解:使学生从理论到仿真,从数学推导到可视化的验证,构建全面的知识体系,增强 解决复杂工程问题的能力。
关键词:阻抗匹配;单支节匹配网络;微带线;电磁仿真中图分类号:G433 文献标识码:A 文章编号:1002-4956(2021)02-0204-04Teaching experiment of impedance matching designbased on CST simulation softwareLIAO Zhen1,LIAO Zhibin2,LIU Yuping2(1. School of Electronics and Information, Hangzhou Dianzi University, Hangzhou 310018, China;2. School of Mathematics and Computer, Xinyu University, Xinyu 338000, China)A bstract: The theory o f transmission line impedance matching is an important theory in electromagnetic field and microwave technology, and it is the fundamental o f radio and microwave circuit design. But the relative concepts are abstract and teaching process is based on mathematical derivation, which makes it difficult for students to understand. By taking a typical project o f the microstrip impedance matching as an example, the impedance matching network is designed by combining theoretical deduction with simulation, which has enhanced students’understanding o f transmission line impedance. The experiment is helpful to construct a comprehensive knowledge structure from theory to simulation and from formula deprivation to visual presentation and enhance students1 ability to solve complex engineering problems.Key w ords: impedance matching; single-stub matching network; microstrip; electromagnetic simulation随着通信技术的蓬勃发展,社会对射频微波技术 人才的需求也与日俱增+3]。
rf and microwave circuit design pdfRF (Radio Frequency) and Microwave Circuit Design is a crucial area in the realm of electronics engineering. This technology enables the development of wireless communication systems, such as radio broadcasting, satellite communication, mobile networks, and radar systems. An RF and MicrowaveCircuit Design PDF provides a comprehensive guide to the theory, design, and implementation of RF and microwave circuits. In this article, we will discuss the various steps involved in RF and Microwave Circuit Design.Step 1: Understanding the Basics of RF and Microwave Circuit DesignBefore starting the design process, it is essential to have a solid grasp of the theory and concepts behind RF and Microwave circuitry. This includes understanding electromagnetic waves, transmission lines, impedance matching, and various other aspects of the RF and microwave spectrum.Step 2: Selecting the Desired Frequency BandThe selection of a frequency band is a critical step in the design process. The band of frequencies that you choose will depend on the particular application of the circuit. For example, a circuit designed for wireless communication will typically operate in the GHz (Gigahertz) range, while acircuit for a radar system might operate in the low MHz (Megahertz) range.Step 3: Designing the Circuit SchematicThe circuit schematic is the blueprint for the actualhardware implementation of the RF or microwave circuit. It isessential to design a schematic that accurately represents the desired functionality of the circuit. This includes selecting appropriate active and passive components, such as transistors, diodes, capacitors, and resistors.Step 4: Simulating and Testing the Circuit Design Simulating and testing the circuit design is a crucial stepin the design process. Computer-aided design (CAD) software can be used to simulate the circuit, enabling the designer to identify potential problems and modify the design as needed. Once the simulation is complete, the circuit should be tested in a real-world environment to ensure that it meets the desired specifications and performance requirements.Step 5: Fabricating the PCB BoardOnce the circuit design has been simulated and tested successfully, it is time to fabricate the printed circuit board (PCB). The PCB is the physical implementation of the circuit schematic and is the backbone of the overall circuit design.Step 6: Final Assembly and TestingThe final step in the design process is to assemble and test the completed circuit. This includes soldering components to the PCB, connecting any external components or peripherals, and conducting comprehensive testing to ensure that thecircuit meets the desired specifications and performance requirements.In conclusion, RF and microwave circuit design is a complex and critical area in electronics engineering. The design process involves understanding the theory and concepts of RF and Microwave circuitry, selecting the desired frequency band, designing the circuit schematic, simulating and testing the circuit design, fabricating the PCB board,and final assembly and testing. By following these steps, electronics engineers can design and implement high-performance RF and Microwave circuits that are optimized for their specific applications.。
无线通信英文版教学设计1. IntroductionWireless communication is the exchange of information between two or more devices without the use of cables or wires. Wireless communication is an essential part of modern life and has transformed the way we communicate. This course is designed to provide students with a solid foundation in wireless communication principles, practices, and technologies.2. Course ObjectivesThe objectives of this course are: - To introduce the fundamental principles of wireless communication. - To expln the different types of wireless communication systems and their applications. - To teach the basic concepts of radio frequency (RF) technology and wireless network architecture. - To discuss the various communication standards that govern wireless communication. - To provide hands-on experience in building wireless communication systems.3. Course OutlineThe course will cover the following topics:Week 1: Introduction to Wireless Communication•Overview of wireless communication•Types of wireless communication systems•Applications of wireless communicationWeek 2: Basic Concepts of Radio Frequency (RF) Technology•RF waves and signals•Modulation techniques•Demodulation techniquesWeek 3: Wireless Network Architecture•Wireless network topologies•Wireless access points and routers•Wireless network securityWeek 4: Wireless Communication Standards•IEEE 802.11 (Wi-Fi)•Bluetooth•Cellular networks (GSM, CDMA)Week 5: Building Wireless Communication Systems•Basic hardware components of a wireless communication system•Installing and configuring a wireless access point•Troubleshooting wireless network issues4. Teaching MethodologyThis course will be delivered through a combination of lectures, readings, assignments, and hands-on projects. Lectures will provide an introduction to the topic and cover the theoretical aspects of wireless communication. Readings will supplement the lectures and provide additional information on the course topics. Assignments will be given to evaluate the student’s understandin g of the course material. Hands-on projects will provide practical experience in building wireless communication systems.5. Assessment and GradingThe grade for this course will be based on the following components: Component WeightageAssignments 40%Hands-on Projects 30%Final Exam 30%6. References•Andreas F. Molisch,。
一种最优化瞬态响应的功率控制技术顾汉清;盛胜君【摘要】在需要快速实现对射频大功率幅度进行控制的场合,数字控制和传统模拟控制电路存在各自弊端。
该文阐述了利用开关电容放大技术解决大功率发射机ALC电路的过冲问题,并利用相位补偿,实现瞬态响应速度和稳定性的最优化。
测试结果表明该设计方法满足工程使用要求。
%Whether digital or traditional analog control circuit , there are still some disadvantage in fast trans-mitter amplitude control , in order to solve the problem of overshoot in high power transmitter , a switch-capacitor amplifier is introduced in this paper , an optimum transient response and stability is achieved using phase compensation and proof good in the experiment result .【期刊名称】《杭州电子科技大学学报》【年(卷),期】2013(000)005【总页数】4页(P25-28)【关键词】自动电平控制;开关电容;瞬态响应;穿越频率;相位裕量;相位补偿【作者】顾汉清;盛胜君【作者单位】中国电子科技集团公司第三十六研究所,浙江嘉兴314033;中国电子科技集团公司第三十六研究所,浙江嘉兴314033【正文语种】中文【中图分类】TN7220 引言在大功率发射机中,采用闭环自动电平控制(Automatic Level Control,ALC)实现发射功率的控制,使得发射机在不同环境条件和负载条件下输出功率稳定并达到额定值。
ALC的设计需保证在瞬态响应过程中,避免功率放大器由于过激励形成大功率瞬态脉冲造成的损坏;瞬态响应时间设计应遵循在保证发射机工作可靠的条件下尽量快,使发射机能满足不同工作体制如快速跳频通信体制。
mmpi2rf题计分方式英文回答:The MMPI-2-RF (Minnesota Multiphasic Personality Inventory-2 Restructured Form) is a widely used psychological assessment tool that measures various aspects of an individual's personality and psychopathology. It consists of 338 true/false questions that cover a range of psychological domains such as depression, anxiety, paranoia, and social introversion. The scoring of the MMPI-2-RF involves several steps to interpret the results accurately.Firstly, the raw scores are calculated by assigning one point for each endorsed item. These raw scores are then converted into T-scores, which have a mean of 50 and a standard deviation of 10. T-scores allow for comparisonwith a normative sample and provide information about the individual's relative standing on each scale. Higher T-scores indicate a higher level of endorsement for specific psychological traits or symptoms.Next, the validity scales are examined to assess the individual's response style and the overall validity of the test results. These scales can detect response patternsthat may indicate malingering, defensiveness, or random responding. They also help identify potential issues with the individual's understanding of the test or deliberate attempts to distort the results.After evaluating the validity scales, the clinical scales are analyzed to assess specific personality traits and psychopathology. There are 42 clinical scales in the MMPI-2-RF, which provide information about various aspects of psychopathology, including depression, anxiety, schizophrenia, and personality disorders. Each scale consists of several items that measure different facets of the construct being assessed.In addition to the clinical scales, the MMPI-2-RF also includes several supplemental scales that provideadditional information about the individual's psychological functioning. These scales assess areas such as substanceabuse, aggression, and somatic symptoms. The interpretation of these scales is based on the individual's T-scores and can provide valuable insights into specific areas of concern.Overall, the MMPI-2-RF scoring process involves converting raw scores into T-scores, examining validity scales, analyzing clinical scales, and considering supplemental scales. This comprehensive approach allows for a thorough assessment of an individual's personality and psychopathology, helping clinicians make informed decisions regarding diagnosis, treatment planning, and intervention strategies.中文回答:MMPI-2-RF(Minnesota Multiphasic Personality Inventory-2 Restructured Form)是一种广泛使用的心理评估工具,用于测量个体的人格和心理病理学的各个方面。
empirical◙adj. [usually before noun]• based on experiments or experience rather than ideas or theories• 以实验(或经验)为依据的;经验主义的:»empirical evidence / knowledge / research实践经验的证明;从实际经验中获得的知识;以实验为基础的研究»an empirical study经验式研究【OPP】theoretical♦empirically/ -kli / adv.:»Such claims need to be tested empirically.这类断言需要实践来检验。
formulationnoun1.[mass noun] the action of creating or preparing something•创建或准备某物的动作the formulation of foreign policy外交政策的制定■[count noun] a particular expression of an idea, thought, or theory2. a material or mixture prepared according to a formuladeductive◙adj. [usually before noun]• using knowledge about things that are generally true in order to think about and understand particular situations or problems• 演绎的;推论的;推理的:»deductive logic / reasoning演绎逻辑/推理--› compare inductive(1)presence◙noun1. [U] (of a person 人) the fact of being in a particular place• 在场;出席:»He hardly seemed to notice my presence.他似乎没有注意到我在场。
Abstract:This extensive analysis delves into the intricate details and multi-faceted aspects of CO2 metal tube radio frequency (RF) lasers, emphasizing their exceptional quality and adherence to high industry standards. Spanning over 1345 words, the discussion covers the fundamental principles, operational mechanisms, key features, applications, performance benchmarks, maintenance requirements, and future advancements in this cutting-edge technology. The objective is to provide readers with a thorough understanding of the CO2 metal tube RF laser's superiority and its pivotal role in various industrial sectors.1. IntroductionCO2 metal tube RF lasers represent a pinnacle of innovation in the realm of laser technology, offering unparalleled precision, efficiency, and reliability in material processing tasks. These lasers, harnessing the power of carbon dioxide molecules stimulated by radio frequency energy, have established themselves as indispensable tools across diverse industries, ranging from aerospace and automotive to medical device manufacturing and packaging. This comprehensive analysis explores the intricacies of CO2 metal tube RF lasers, examining their underlying principles, technical specifications, applications, and future prospects, all while maintaining a focus on their unwavering commitment to high quality and stringent standards.2. Fundamental Principles and Operational MechanismsAt the core of a CO2 metal tube RF laser lies the principle of stimulated emission. The laser cavity contains a mixture of carbon dioxide, nitrogen, hydrogen, and helium gases, which, when excited by an RF electric field, undergoes population inversion. This process enables the CO2 molecules to transition from higher energy states to lower ones, releasing photons of coherent light at a characteristic wavelength of 10.6 μm. The RF excitation, typically generated by a resonant RF circuit, ensures uniform energy distribution and enhanced stability compared to DC-excited or transverse discharge systems.The metal tube serves as the containment vessel for the gas mixture, providing robustness, thermal conductivity, and precise optical alignment. The tube is designed with highly reflective inner surfaces to facilitate multiple passes of the laser beam, amplifying it through constructive interference. Additionally, the RF laser incorporates advanced cooling systems, such as water jackets or forced-air cooling, to maintain optimal operating temperatures and ensure long-lasting performance.3. Key Features and Performance BenchmarksCO2 metal tube RF lasers are renowned for several distinguishing features that contribute to their high-quality and standard-compliant performance:a. **Versatility:** Capable of processing a wide range of materials, including metals, plastics, ceramics, glass, textiles, and wood, these lasers exhibit excellent versatility, making them suitable for numerous applications.b. **Precision and Speed:** With beam quality factors (M²values) typically ranging from 2 to 7, CO2 RF lasers deliver highly focused, controllablebeams, enabling precise cutting, engraving, and welding at rapid speeds. Their high peak powers and repetition rates further enhance productivity.c. **Efficiency and Reliability:** The RF excitation mechanism ensures efficient energy transfer to the lasing medium, resulting in superior electrical-to-optical conversion efficiencies (typically around 10-20%). Moreover, the metal tube design, combined with advanced cooling systems, promotes longevity and minimal downtime.d. **Environmental Compatibility:** CO2 metal tube RF lasers emit minimal ultraviolet (UV) and infrared (IR) radiation, reducing potential hazards to operators and the environment. They also feature efficient fume extraction systems to manage byproducts generated during material processing.4. ApplicationsCO2 metal tube RF lasers find extensive use in various industrial sectors due to their remarkable performance characteristics:a. **Manufacturing:** Precision cutting, drilling, and welding of metals and non-metals in automotive, aerospace, electronics, and appliance production.b. **Packaging and Printing:** Marking, coding, and cutting of cardboard, paper, and plastic packaging materials; trimming and die-cutting in the converting industry.c. **Medical Devices:** Microprocessing of polymers, ceramics, and metals for medical implants, surgical instruments, and diagnostic equipment.d. **Textiles and Leather:** Cutting, engraving, and marking of fabrics, leather goods, and footwear components.e. **Architecture and Artwork:** Laser cutting and engraving of acrylics, woods, and metals for architectural models, signage, and decorative elements.5. Maintenance Requirements and Service LifeMaintaining a CO2 metal tube RF laser involves regular inspection, cleaning, and calibration of critical components, such as the optical path, gas supply system, and cooling apparatus. The service life of the metal tube itself can span several thousand hours, depending on usage conditions and adherence to recommended maintenance schedules. Replacement tubes, manufactured to exacting standards, ensure seamless integration and continued high-performance operation.6. Future Advancements and TrendsOngoing research and development in CO2 metal tube RF laser technology aim to enhance performance, reduce costs, and expand application areas. Key trends include:a. **Integration of Artificial Intelligence (AI):** AI algorithms can optimize laser parameters in real-time, adapting to varying material properties and processing requirements, thereby enhancing productivity and quality.b. **Miniaturization and Modular Design:** Smaller, lighter, and more versatile laser systems are being developed, enabling easier integration into existing production lines and facilitating mobile applications.c. **Energy Efficiency and Sustainability:** Efforts are underway tofurther improve energy conversion efficiencies and minimize environmental impacts, such as through the use of eco-friendly gases and advanced waste management systems.d. **Hybrid Laser Systems:** Combining CO2 RF lasers with other laser sources, such as fiber or disk lasers, can offer unique processing capabilities, expanding the range of materials and applications addressed.ConclusionCO2 metal tube RF lasers exemplify the fusion of advanced scientific principles and engineering excellence, delivering high-quality, high-standard performance across a multitude of industrial applications. Their versatility, precision, speed, efficiency, and reliability, coupled with ongoing technological advancements, solidify their position as indispensable tools in modern manufacturing and processing environments. As research continues to push the boundaries of laser technology, the future of CO2 metal tube RF lasers appears promising, with potential for even greater versatility, sustainability, and cost-effectiveness, ensuring their enduring relevance in the ever-evolving landscape of material processing.。
MPI Probe Selection GuideWith a critical understanding of the numerous measurement challenges associated with today’s RF ap-plications, MPI Corporation has developed TITAN™ RF Probes, a product series specifically optimized for these complex applications centered upon the requirements of advanced RF customers.TITAN™ Probes provide the latest in technology and manufacturing advancements within the field of RF testing. They are derived from the technology transfer that accompanied the acquisition of Allstron, then significantly enhanced by MPI’s highly experienced RF testing team and subsequently produced utilizing MPI’s world class MEMS technology. Precisely manufactured, the TITAN™ Probes include matched 50 Ohm MEMS contact tips with improved probe electrical characteristics which allow the realization of unmat -ched calibration results over a wide frequency range. The patented protrusion tip design enables small passivation window bond pad probing, while significantly reducing probe skate thus providing the out -standing contact repeatability required in today’s extreme measurement environments. TITAN TM Probes with all their features are accompanied by a truly affordable price.The TITAN™ Probe series are available in single-ended and dual tip configurations, with pitch range from 50 micron to 1250 micron and frequencies from 26 GHz to 110 GHz. TITAN™ RF Probes are the ideal choice for on-wafer S-parameter measurements of RF, mm-wave devices and circuits up to 110 GHz as well as for the characterization of RF power devices requiring up to 10 Watts of continuous power. Finally, customers can benefit from both long product life and unbeatable cost of ownership which they have desired foryears.Unique design of the MEMS coplanar contacttip of the TITAN™ probe series.DC-needle-alike visibility of the contact point and the minimal paddamage due to the unique design of the tipAC2-2 Thru S11 Repeatability. Semi-Automated System.-100-80-60-40-200 S 11 E r r o r M a g n i t u d e (d B )Frequency (GHz)Another advantage of the TITAN™ probe is its superior contact repeatability, which is comparable with the entire system trace noise when measured on the semi-automated system and on gold contact pads.CROSSTALKCrosstalk of TITAN™ probes on the short and the bare ceramic open standard of 150 micron spacing compared to conventional 110 GHz probe technologies. Results are corrected by the multiline TRL calibration. All probes are of GSG configuration and 100 micron pitch.-80-60-40-200Crosstalk on Open. Multiline TRL Calibration.M a g (S21) (d B )Frequency (GHz)-80-60-40-200Crosstalk on Short. Multiline TRL Calibration.M a g (S21) (d B )Frequency (GHz)The maximal probe c ontac t repeatability error of the c alibrate S11-parameter of the AC2-2 thru standard by T110 probes. Semi-automated system. Ten contact circles.Cantilever needle material Ni alloy Body materialAl alloy Contact pressure @2 mils overtravel 20 g Lifetime, touchdowns> 1,000,000Ground and signal alignment error [1]± 3 µm [1]Planarity error [1] ± 3 µm [1]Contact footprint width < 30 µm Contact resistance on Au < 3 mΩThermal range-60 to 175 °CMechanical CharacteristicsAC2-2 Thru S21 Repeatability. Manual TS50 System.-100-80-60-40-200S 21 E r r o r M a g n i t u d e (d B )Frequency (GHz)MECHANICAL CHARACTERISTICSThe maximal probe c ontac t repeatability error of the c alibrate S21-parameter of the AC2-2 thru standard by T50 probes. Manual probe system TS50.26 GHZ PROBES FOR WIRELESS APPLICATIONSUnderstanding customer needs to reduce the cost of development and product testing for the high competitive wireless application market, MPI offers low-cost yet high-performance RF probes. The specifically developed SMA connector and its outstanding transmission of electro-magnetic waves through the probe design make these probes suitable for applications frequencies up to 26 GHz. The available pitch range is from 50 micron to 1250 micron with GS/SG and GSG probe tip configurations. TITAN™ 26 GHz probes are the ideal choice for measurement needs when developing components for WiFi, Bluetooth, and 3G/4G commercial wireless applications as well as for student education.Characteristic Impedance 50 ΩFrequency rangeDC to 26 GHz Insertion loss (GSG configuration)1< 0.4 dB Return loss (GSG configuration)1> 16 dB DC current ≤ 1 A DC voltage ≤ 100 V RF power, @10 GHz≤ 5 WTypical Electrical Characteristics26 GHz Probe Model: T26Connector SMAPitch range50 µm to 1250 µm Standard pitch step from 50 µm to 450 µm from 500 µm to 1250 µm25 µm step 50 µm stepAvailable for 90 µm pitch Tip configurations GSG, GS, SG Connector angleV-Style: 90-degree A-Style: 45-degreeMechanical CharacteristicsT26 probe, A-Style of the connectorTypical Electrical Characteristics: 26 GHz GSG probe, 250 micron pitchPROBES FOR DEVICE AND IC CHARACTERIZATION UP TO 110 GHZTITAN™ probes realize a unique combination of the micro-coaxial cable based probe technology and MEMS fabricated probe tip. A perfectly matched characteristic impedance of the coplanar probe tips and optimized signal transmission across the entire probe down to the pads of the device under test (DUT) result in excellent probe electrical characteristics. At the same time, the unique design of the probe tip provides minimal probe forward skate on any type of pad metallization material, therefo -re achieving accurate and repeatable measurement up to 110 GHz. TITAN™ probes are suitable for probing on small pads with long probe lifetime and low cost of ownership.The TITAN™ probe family contains dual probes for engineering and design debug of RF and mm-wave IC’s as well as high-end mm-wave range probes for S-parameter characterization up to 110 GHz for modeling of high-performance microwave devices.Characteristic Impedance 50 ΩFrequency rangeDC to 40 GHz Insertion loss (GSG configuration)1< 0.6 dB Return loss (GSG configuration)1> 18 dB DC current ≤ 1 A DC voltage ≤ 100 V RF power, @10 GHz≤ 5 WTypical Electrical Characteristics40 GHz Probe Model: T40Connector K (2.92 mm)Pitch range50 µm to 500 µmStandard pitch step For GSG configuration:from 50 µm to 450 µm from 500 µm to 800 µmFor GS/SG configuration:from 50 µm to 450 µm 25 µm step 50 µm stepAvailable for 90 µm pitch25 µm stepAvailable for 90/500 µm pitch Tip configurations GSG, GS, SG Connector angleV-Style: 90-degree A-Style: 45-degreeMechanical CharacteristicsTypical Electrical Characteristics: 40 GHz GSG probe, 150 micron pitchT40 probe, A-Style of the connectorCharacteristic Impedance50 ΩFrequency range DC to 50 GHz Insertion loss (GSG configuration)1< 0.6 dB Return loss (GSG configuration)1> 17 dBDC current≤ 1 ADC voltage≤ 100 VRF power, @10 GHz≤ 5 W Typical Electrical Characteristics Connector Q (2.4 mm)Pitch range50 µm to 250 µm Standard pitch stepFor GSG configuration: from 50 µm to 450 µm For GS/SG configuration: from 50 µm to 450 µm 25 µm stepAvailable for 90/500/550 µm pitch 25 µm stepAvailable for 90/500 µm pitchTip configurations GSG, GS, SG Connector angle V-Style: 90-degreeA-Style: 45-degreeMechanical CharacteristicsT50 probe, A-Style of the connectorTypical Electrical Characteristics: 50 GHz GSG probe, 150 micron pitchCharacteristic Impedance50 ΩFrequency range DC to 67 GHz Insertion loss (GSG configuration)1< 0.8 dB Return loss (GSG configuration)1> 16 dBDC current≤ 1 ADC voltage≤ 100 VRF power, @10 GHz≤ 5 W Typical Electrical Characteristics Connector V (1.85 mm)Pitch range50 µm to 250 µm Standard pitch stepFor GSG configuration: from 50 µm to 400 µm For GS/SG configuration: from 50 µm to 250 µm 25 µm step Available for 90 µm pitch25 µm step Available for 90 µm pitchTip configurations GSG Connector angle V-Style: 90-degreeA-Style: 45-degreeMechanical CharacteristicsT67 probe, A-Style of the connectorTypical Electrical Characteristics: 67 GHz GSG probe, 100 micron pitchCharacteristic Impedance 50 ΩFrequency rangeDC to 110 GHz Insertion loss (GSG configuration)1< 1.2 dB Return loss (GSG configuration)1> 14 dB DC current ≤ 1 A DC voltage ≤ 100 V RF power, @10 GHz≤ 5 WTypical Electrical CharacteristicsMechanical CharacteristicsTypical Electrical Characteristics: 110 GHz GSG probe, 100 micron pitchT110 probe, A-Style of the connectorCharacteristic impedance50 ΩFrequency range DC to 220 GHz Insertion loss (GSG configuration)1< 5 dB Connector end return loss(GSG configuration)1> 9 dBTip end return loss(GSG configuration)1> 13 dBDC current≤ 1.5 ADC voltage≤ 50 V Typical Electrical CharacteristicsConnector Broadband interface Pitch range50/75/90/100/125 µm Temperature range -40 ~ 150 ºC Contact width15 µmquadrant compatible(allowing corner pads)Yes recommended pad size20 µm x 20 µm recommended OT (overtravel)15 µmcontact resistance(on Al at 20 ºC using 15 µm OT)< 45 mΩlifetime touchdowns(on Al at 20 ºC using 15 µm OT)> 200,000Mechanical CharacteristicsT220 probe, broadband interface Typical Performance (at 20 ºC for 100 µm pitch)BODY DIMENSIONS PROBES Single-Ended V-StyleT220 GHz Probe1.161.1628.328437.455.6512.5527.73Single-Ended A-StyleCALIBRATION SUBSTRATESAC-series of calibration standard substrates offers up to 26 standard sets for wafer-level SOL T, LRM probe-tip cali -bration for GS/SG and GSG probes. Five coplanar lines provide the broadband reference multiline TRL calibration as well as accurate verification of conventional methods. Right-angled reciprocal elements are added to support the SOLR calibration of the system with the right-angled configuration of RF probes. A calibration substrate for wide-pitch probes is also available.Material Alumina Elements designCoplanarSupported calibration methods SOLT, LRM, SOLR, TRL and multiline TRL Thickness 635 µmSizeAC2-2 : 16.5 x 12.5 mm AC3 : 16.5 x 12.5 mm AC5 : 22.5 x 15 mm Effective velocity factor @20 GHz0.45Nominal line characteristic impedance @20 GHz 50 ΩNominal resistance of the load 50 ΩTypical load trimming accuracy error ± 0.3 %Open standardAu pads on substrate Calibration verification elements Yes Ruler scale 0 to 3 mm Ruler step size100 µmCalibration substrate AC2-2Probe Configuration GSGSupported probe pitch100 to 250 µm Number of SOL T standard groups 26Number of verification and calibration lines5Calibration substrate AC-3Probe Configuration GS/SG Supported probe pitch50 to 250 µm Number of SOL T standard groups 26Number of verification and calibration lines5Calibration substrate AC-5Probe Configuration GSG, GS/SG Supported probe pitch250 to 1250 µm Number of SOL T standard groups GSG : 7GS : 7SG : 7Open standardOn bare ceramic Number of verification and calibration linesGSG : 2GS : 1Typical characteristics of the coplanar line standard of AC2-2 calibration substrate measured using T110-GSG100 probes, and methods recommended by the National Institute of Standard and Technologies [2, 3].2468(d B /c m )F requency (G Hz)α-6-4-202I m a g (Z 0) ()F requency (G Hz)AC2-2 W#006 and T110A-GSG100Ω2.202.222.242.262.282.30 (u n i t l e s s )F requency (G Hz)β/βо4045505560R e a l (Z 0) ()F requency (G Hz)ΩTypical Electrical CharacteristicsMPI QAlibria® RF CALIBRATION SOFTWAREMPI QAlibria® RF calibration software has been designed to simplify complex and tedious RF system calibration tasks. By implementing a progressive disclosure methodology and realizing intuitive touch operation, QAlibria® provides crisp and clear guidance to the RF calibration process, minimizing con-figuration mistakes and helping to obtain accurate calibration results in fastest time. In addition, its concept of multiple GUI’s offers full access to all configuration settings and tweaks for advanced users. QAlibria® offers industry standard and advanced calibration methods. Furthermore, QAlibria® is integrated with the NIST StatistiCal™ calibration packages, ensuring easy access to the NIST mul-tiline TRL metrology-level calibration and uncertainty analysis.MPI Qalibria® supports a multi-language GUI, eliminating any evitable operation risks and inconvenience.SpecificationsRF AND MICROWAVE CABLESMPI offers an excellent selection of flexible cables and acces-sories for RF and mm-wave measurement applications forcomplete RF probe system integration.CablesHigh-quality cable assemblies with SMA and 3.5 mm connectorsprovide the best value for money, completing the entry-level RFsystems for measurement applications up to 26 GHz. Phase stab-le high-end flexible cable assemblies with high-precision 2.92, 2.4, 1.85 and 1 mm connectors guarantee high stability, accuracy and repeatability of the calibration and measurement for DC applications up to 110 GHz.MPI offers these cable assemblies in two standard lengths of 120 and 80 cm, matching the probe system’s footprint and the location of the VNA.Cables Ordering InformationMRC-18SMA-MF-80018 GHz SMA flex cable SMA (male) - SMA (female), 80 cmMRC-18SMA-MF-120018 GHz SMA flex cable SMA (male) - SMA (female), 120 cmMRC-26SMA-MF-80026 GHz SMA flex cable SMA (male) - SMA (female), 80 cmMRC-26SMA-MF-120026 GHz SMA flex cable SMA (male) - SMA (female), 120 cmMRC-40K-MF-80040 GHz flex cable 2.92 mm (K) connector, male-female, 80 cm longMRC-40K-MF-120040 GHz flex cable 2.92 mm (K) connector, male-female, 120 cm longMRC-50Q-MF-80050 GHz flex cable 2.4 mm (Q) connector, male-female , 80 cm longMRC-50Q-MF-120050 GHz flex cable 2.4 mm (Q) connector, male-female , 120 cm longMRC-67V-MF-80067 GHz flex cable 1.85 mm (V) connector, male-female, 80 cm longMRC-67V-MF-120067 GHz flex cable 1.85 mm (V) connector, male-female, 120 cm longMMC-40K-MF-80040 GHz precision flex cable 2.92 mm (K) connector, male-female, 80 cm long MMC-40K-MF-120040 GHz precision flex cable 2.92 mm (K) connector, male-female, 120 cm long MMC-50Q-MF-80050 GHz precision flex cable 2.4 mm (Q) connector, male-female , 80 cm long MMC-50Q-MF-120050 GHz precision flex cable 2.4 mm (Q) connector, male-female , 120 cm long MMC-67V-MF-80067 GHz precision flex cable 1.85 mm (V) connector, male-female, 80 cm long MMC-67V-MF-120067 GHz precision flex cable 1.85 mm (V) connector, male-female, 120 cm long MMC-110A-MF-250110 GHz precision flex cable 1 mm (A) connector, male-female, 25 cm longMPI Global PresenceDirect contact:Asia region: ****************************EMEA region: ******************************America region: ********************************MPI global presence: for your local support, please find the right contact here:/ast/support/local-support-worldwide© 2023 Copyright MPI Corporation. All rights reserved.[1] [2][3] REFERENCESParameter may vary depending upon tip configuration and pitch.R. B. Marks and D. F. Williams, "Characteristic impedance determination using propagation constant measu -rement," IEEE Microwave and Guided Wave Letters, vol. 1, pp. 141-143, June 1991.D. F. Williams and R. B. Marks, "Transmission line capacitance measurement," Microwave and Guided WaveLetters, IEEE, vol. 1, pp. 243-245, 1991.AdaptersHigh-In addition, high-quality RF and high-end mm-wave range adapters are offered to address challenges ofregular system reconfiguration and integration with different type of test instrumentation. MRA-NM-350F RF 11 GHz adapter N(male) - 3.5 (male), straight MRA-NM-350M RF 11 GHz adapter N(male) - 3.5 (female), straightMPA-350M-350F Precision 26 GHz adapter 3.5 mm (male) - 3.5 mm (female), straight MPA-350F-350F Precision 26 GHz adapter 3.5 mm (female) - 3.5 mm (female), straight MPA-350M-350M Precision 26 GHz adapter 3.5 mm (male) - 3.5 mm (male), straight MPA-292M-240F Precision 40 GHz adapter 2.92 mm (male) - 2.4 mm (female), straight MPA-292F-240M Precision 40 GHz adapter 2.92 mm (female) - 2.4 mm (male), straight MPA-292M-292F Precision 40 GHz adapter 2.92 mm (male) - 2.92 mm (female), straight MPA-292F-292F Precision 40 GHz adapter 2.92 mm (female) - 2.92 mm (female), straight MPA-292M-292M Precision 40 GHz adapter 2.92 mm (male) - 2.92 mm (male), straight MPA-240M-240F Precision 50 GHz adapter 2.4 mm (male) - 2.4 mm (female), straight MPA-240F-240F Precision 50 GHz adapter 2.4 mm (female) - 2.4 mm (female), straight MPA-240M-240M Precision 50 GHz adapter 2.4 mm (male) - 2.4 mm (male), straight MPA-185M-185F Precision 67 GHz adapter 1.85 mm (male) -1.85 mm (female), straight MPA-185F-185F Precision 67 GHz adapter 1.85 mm (female) -1.85 mm (female), straight MPA-185M-185M Precision 67 GHz adapter 1.85 mm (male) -1.85 mm (male), straight MPA-185M-100FPrecision 67 GHz adapter 1.85 mm (male) -1.00 mm (female), straightDisclaimer: TITAN Probe, QAlibria are trademarks of MPI Corporation, Taiwan. StatistiCal is a trademark of National Institute of Standards and Technology (NIST), USA. All other trademarks are the property of their respective owners. Data subject to change without notice.。
基于超声 RF 信号的超声成像实验设计黄韫栀;刘奇;肖勇【摘要】In order to better understand intuitively the process of reconstructing B -mode images from focused ultrasound RF sig-nal for undergraduate students,an experiment is well designed.Firstly,it makes students complete the collection of RF data on ultra-sound equipment.Secondly,it completes imaging process simulation by analyzing the collected signals in each imaging module on MAT-LABplatform.Finally,it compares the obtained results with shown image in ultrasound equipment.This experiment allows students par-ticipating in designing with an opening result.The practical result shows that:the experiment process can not only help students in-crease the ability to analyze certain problem,but also deepen students'understanding of the curriculum,stimulate their interest in learning.Thus this experiment will achieve the purpose of improving the teaching effect and quality.%该文为让学生更直观地了解超声 RF 信号重建出 B 超图像的过程,首先在超声设备上完成RF 数据的采集,然后在 Matlab 平台上对每个成像步骤的信号进行分析,完成成像过程的仿真,最后将得到的结果与超声设备上显示的图像进行对比。
分解学术英语教程2 答案Unit 1 Multidisciplinary EducationKeys to the ExercisesApproaching the Topic1. 1) The aim of college education is to produce individuals who are well on their way to becomeexperts in their field of interest.2) The growing importance of producing professionals who have the skills to work with peoplefrom a diverse set of disciplines.3) First, through an interdisciplinary approach; Second, through a multidisciplinary approach.4) College education should produce individuals who may later become expert who areinterdisciplinary problem solvers.2. 1) f 2) d 3) a 4) e 5) g 6) m 7) j 8) k 9) l 10) i 11) b 12) h 13) c4. (1) offered (2) stresses (3) ability (4) different (5) approach(6) increasingly (7) graduates (8) enter (9) positions (10) Employment6. 1) Multidisciplinary studies.2) They both believe that current college education should lay emphasis on multidisciplinarystudies, which is a prerequisite to producing future expert who are interdisciplinary problemsolvers.3) Open.4) Open.5) Open.Reading about the Topic3. 1) The students have brought to MIT their individual gifts, such as their own intellect, energy,ideas, aspirations, distinctive life experience and point of view, etc.2) They represent the geographic and symbolic center of MIT.3) Names of intellectual giants.4) Leonardo da Vinci was a painter, scientist, engineer, sculptor, inventor, city planner andarchitect.4.Set 1: 1) c 2) e 3) d 4) h 5) a 6) g 7) f 8) bSet 2: 1) e 2) a 3) h 4) b 5) c 6) f 7) d 8) g 5.(b) Para. A (b) Para. B (a) Para. C (c) Para. D(f) Para. E (e) Para. F (d) Para. G (g) Para. A6. 1) Because for him, the simplicity he appreciated in nature became his ultimate standard indesign.2) First was da Vinci’s complete disregard for the accepted boundaries between different f ieldsof knowledge. The second facet of da Vinci’s character was his respect for and fascinationwith nature. The third quality of da Vinci’s character was an enthusiastic demand forhands-on making, designing, practicing and testing, and for solving problems in the real world.3)“There is a good chance that you will never again live and work in a community with as manydifferent cultures and backgrounds as MIT.”(Para. F) 4) Because by doing so, the students can engage themselves in new intellectual adventures so as touse their time at MIT to its fullest potential.5) It means that “They took the initiative to search for the deepest answers, instead of sitting backand letting things happen to them.”7. Set 1: 1) h 2) d 3) a 4) g 5) f 6) e 7) b 8) cSet 2: 1) c 2) g 3) d 4) a 5) h 6) f 7) e 8) b 8. 1) She wanted to describe for the new students three of his characteristics that particularly f itwith the value of MIT.2) Because by doing so, the students can encounter the most stimulating minds and inspiringrole models, experience a life in a community with diversif ied cultures and backgrounds andparticipate in various new intellectual adventures, so that they can get the most out of theirMIT education.3) The three of Da Vinci’s characteristics will be the heritage of MIT to be inherited by thestudents. She hoped that the new students would follow Da Vinci as well as a great manyextraordinary MIT teachers as their role models to use their time to its fullest potential.4) Multidisciplinary thinking is a mode of thinking that goes beyond disciplinary boundaries inorder to gain new ideas and fresh perspectives.9. 1) Human ingenuity will never devise any inventions more beautiful, nor more simple, nor moreto the purpose than Nature does. (Para. A)2) For Da Vinci, the simplicity he appreciated in Nature became his ultimate standard in design.(Para. B)3) Be as determined in your curiosity as Leonardo da Vinci — and you will use your time atMIT to its fullest potential. (Para. F)4) MIT is a place of practical optimism and of passionate engagement with the most importantproblems of the world. (Para. G)5) I had long since observed that people of accomplishment rarely sat back and let thingshappen to them. (Para. H)10. Many scientists and engineers at MIT pursue simplicity in their design and development oftechnologies.Exploring the Topic4. 1) It is believed that a multidisciplinary approach to scientific education is of vital importance.2) Second, a multidisciplinary emphasis is believed to be a prerequisite to training individuals.3) It cannot be denied that these f irms areparticipating in turning out the future thinkers.4) How about examining our problems about science and technology from a liberal artsperspective.5) Surprisingly, however, our universities and colleges fail to switch from the conventionaldivisions and departmental sections to daily extracurricular multidisciplinary work.5. Reading 1 begins with a contrast —“College education has always had the responsibility to ...However, ... we also see the growing importance of producing ...”. The introduction of Reading2 is informative as well as interesting, which arouses the readers’ interest to go on reading.Integrated Exercises2. (1) ultimate (2) spirit (3) feed (4) approach (5) property (6) represent(7) discipline (8) aspiration (9) inspire (10) perspective (11) inherit (12) generate3.(1) inspiring (2) generation (3) collaborative (4) aspiring (5) Intelligent(6) inherit (7) celebrity (8) speculated (9) representative (10) anatomical4. (1) D (2) A (3) C (4) B (5) D (6) A (7) B (8) C (9) A (10) C5. (1) Many celebrated researchers around the world are collaborating to develop a new vaccine.(2) The scientists’ experiment generated an unexpected outcome.(3) If the systems are restructured, their effectiveness will be ultimately integrated into theglobal economy.(4) The doctors speculate that he died of a stroke caused by a blow on the head.(5) The murder trial attracted considerable public attention.(6) The aspiration for college education inspires peoplein remote areas to work hard.(7) He inherited his parents’ fortune after their death.(8) He disregarded his father’s advice and left college.(9) In this address, he asked the youngsters, who embody the spirits of the nation, to join thecampaign.(10) The special diet incorporates many different fruits and vegetables.7. (1) Whoever run the red light shows a complete disregard for public safety.(2) Success, as he explained, was nothing more than a consistent pursuit of art and good luck.(3) The new product has benef ited from research work at the crossroads between biological andmedical studies.(4)It was amazing that his idea echoed well the great philosopher’s belief, which he claimed notto have heard about before.(5) The one-month intense training program prepared the team members well for possibleemergencies.(6) The audience was deeply impressed with the vigor andpower of the speech delivered by theenvironmentalist.(7) This traveling experience will provide you with a rare opportunity to sample a different way oflife.(8) Using the limited time to its fullest potential is one of the must-have/required skills in adaptingto the fast-paced modern life.(9) More and more countries are bringing robots to bear on their various problems.(10) These students are encouraged from a very early age to follow their own boundless interestswell beyond the boundaries of conventional belief in obedient learning.8.A. (1) B (2) C (3) B (4) B (5) DB. As multidisciplinary design has become a trend in the industry, there is a need for moreemphasis on multidisciplinary perspectives. Educational institutions should take their role intraining individuals who can function in a collaborative environment and be prepared to facemultifaceted projects that they may not have been exposed to. However, our universities andcolleges fail to shift from traditional divisions and departmental sections to multidisciplinarywork being practiced on a daily basis outside the classroom.C. 1) F 2) T 3) F 4) T 5) TD. (1) what learning is about (2) be inquisitive (3) learn a new subject(4) analyze a new problem (5) teacher-taught (6) master-inspired(7) self-learner (8) the trap of dogma (9) no single simple answer(10) black and white (11) critical thinking (12) tolerant and supportive(13) a new thesis topic (14) flexibility (15) style of leadershipUnit 2 The Scientific MethodKeys to the ExercisesApproaching the Topic1. 1) The Scientific Method is a body of techniques for investigating phenomena and acquiringknowledge, as well as correcting/integrating previous knowledge. It involves gatheringobservable, empirical and measurable evidence, the collection of data through observationand experimentation, and the formulation and testing of hypotheses.2)Scientists put forward hypotheses to explain what is observed. They then conduct experimentsto test these hypotheses. The steps taken in the experiment must be capable of replication andthe results emerge as the same. What is discovered may lead to a new hypothesis.3) Scientists are human and can be unintentionally biased; total objectivity is impossible.4) Scientists are human and can be unintentionally biased. Science uses our senses and our sensescan be mistaken. We can never understand something as it really is because our very presenceaffects what is being studied.5) ① Science is both a body of knowledge and a process.② Sc ience is exciting.③ Science is useful.④ Science is ongoing.⑤ Science is reliable.⑥ Science is a community endeavor.2. 1) c 2) g 3) e 4) f 5) a 6) d 7) h 8) k 9) b 10) i 11) j4. (1) aspects (2) process (3) satisfy (4) technologies(5) puzzle(6) collection (7) evidence (8) ensure (9) diversity (10) professional6. 1) Science.2) It brings to mind many different pictures: white lab coats and microscopes, a scientist peeringthrough a telescope, the launch of the space shuttle, and so on.3) Science can discover the laws to understand the order of nature.4) Because it relies on a systems of checks and balances, which helps ensure that science moves towards greater accuracy and understanding, and this system is facilitated by diversity withinthe scientific community, which offers a range of perspectives on scientific ideas.5) Open.Reading about the Topic3. 1) The modern scientific method is characterized by confirmations and observations which“verified”the theories in q uestion, but some genuinely testable theories, when found to befalse, are still upheld by their admirers, which rescues the theory from refutation only at theprice of destroying, or at least lowering, its scientific status.2) A theory which is not refutable by any conceivable event is non-scientific.3) Their theories were constantly verified by their clinical observations. They always fitted andwere always confirmed.4) Light must be attracted by heavy bodies (such as the sun).5) There is the risk involved in a prediction: the theory is incompatible with certain possibleresults of observation —in fact with results which everybody before Einstein would haveexpected.4. Set 1: 1) c 2) a 3) d 4) b 5) f 6) e 7) h 8) g Set 2: 1) b 2) e 3) a 4) f 5) d 6) c 7) h 8) g5. Para. A (b) Para. B (c) Para. C (e)Para. D (e) Para. E (a) Para. F (d)6. 1) Observations, hypotheses, and deductions, then conclusions.2) You will need to research everything that you can f ind about the problem.3) You shouldn’t change the hypothesis. Instead, try to explain what might have been wrongwith your original hypothesis.4) An important thing to remember during this stage of the scientific method is that once youdevelop a hypothes is and a prediction, you shouldn’t change it, even if the results of yourexperiment show that you were wrong.5) Because there is a chance that you made a miscue somewhere along the way.7. Set 1: 1) c 2) a 3) d 4) b 5) f 6) e 7) h 8) g Set 2: 1) e 2) g 3) a 4) f 5) c 6) b 7) d 8) h 8. 1) Observation, as the f irst stage of the scientific method, is a way of collecting informationfrom any possible sources, which can serve as a foundation in verifying a theory. In thisprocess, one should expect an event which could refute the theory. Only through beingrefuted by new observations which are incompatible with the theory could it be falsified,which ref lects its truescientific virtue.2) A hypothesis is a possible solution to a problem, based on knowledge and research, while atheory is a hypothesis confirmed by the research findings. Every theory cannot be applied toevery situation; otherwise, it is not a good theory. 3) It is always possible to verify nearly every theory, but that would rescue the theory fromrefutation at the price of destroying, or at least lowering its scientific status.4) To falsify a theory is more valuable, because a theory which is not refutable by any conceivableevent is non-scientific.9. 1) Because of this personal experience and an interest in the problem, you decide to learn moreabout what makes plants grow. (Para. B)2) The experiment that you will design is done to test the hypothesis. (Para. D)3) Through informal, exploratory observations of plants in a garden, those with more sunlightappear to grow bigger. (Para. H)4) The judges at your science fair will not take points off simply because your results don’tmatch up with your hypothesis. (Para. K)5) You cannot prove the hypothesis with a single experiment, because there is a chance that youmade a miscue somewhere along the way. (Para. Q)10. Observation, the initial stage of the research, requires a thorough understanding of a researchproject you have chosen by collecting adequate information from various sources, and isfollowed by the next stage known as hypothesis, an uncomplicated statement that defineswhat you think the outcome of your experiment will be. Exploring the Topic4. 1) Science does not include explanations based on no empirical evidence.2) The human nature of science, however, renders it unlikely to be free of personal prejudices,misapprehensions, and bias.3) The scope of science encompasses the whole universe and natural world.4) Science is a process of deciding whether the acquired evidence may prove what is mostlikely to be correct currently.5) It is not possible to prove a hypothesis with a single experiment, as chances are that amistake was made somewhere in the process.Integrated Exercises2. (1) additional (2) illustrate (3) interpret (4) conduct (5) previous (6) involve(7) design (8) verify (9) reflect (10) collect (11) research (12) support3.(1) methodical (2) commitment (3) achievable (4) assume(5) illogical(6) exposure (7) constitutive (8) emphatic (9) confirmation (10) identity4. (1) A (2) B (3) A (4) D (5) A (6) B (7) C (8) A (9) D (10) B5. (1) This observation motivated Newton to develop a theory of gravity.(2) Other scholars attempt to approach the subject from an economical perspective.(3) Participating in the activity will provide one with an initial taste of the objectives ofsociology.(4) Scientists insisted there was a rational explanation for the strange phenomenon.(5) To most young people, higher education is nothing but a process of acquiring knowledge.(6) The study demonstrates the necessity of taking amuch broader view in the matter.(7) The new car’s design successfully integrates art and technology.(8) China actually encountered the identical stages of its development in the early 1990s to theWest.(9) The virus can spread to a document or application between computers and render thecomputer useless.(10) If the sustainable development of small economies is facilitated, their effectiveness will beultimately integrated into the global economy.7. 1) We could not attend a conference without hearing some talks about change and challenge.2) Things seem highly optimistic in the light of numerous reports, especially from countrydistricts.3) I am in favor of the argument that urbanization should be controlled properly.4) Something slowly began to dawn on me —I still loved what I did.5) My computer does not work because it was renderedparalyzed by some viruses.6) Experts are working on the plan in question. And they’ll come to an answer.7) A national curriculum framework is logically incompatible with pupil-centered learning.8) For many women success is often achieved at the price of their married life.9) Many attempts had been made before I successfully entered a key university.10) There is a good chance that it will turn fine tomorrow.8. A. (1) B (2) A (3) C (4) A (5) BB. Understanding scientific method is critical to your scientific endeavor. The scientificmethod is a series of steps that serve as guidelines for scientific efforts, and a tool that helps scientists solve problems and determine answers to questions in a logical format.There are two forms of scientific method: the experimental method and the descriptivemethod. The former employs numerical data and graphs, used in physical sciences, whilethe latter gathers Information through visual observation and interviewing, employed inzoology and anthropology. The scientific method involves five steps, namely, identifying aproblem, researching the problem, formulating a hypothesis, conducting an experiment andreaching a conclusion.C. (1) The process of science, in contrast to the linear steps of the simplified scientific method,is iterative.(2) Science circles back on itself so that useful ideas are built upon and used to learn evenmore about the natural world.(3) Gregor Mendel showed that inheritance is particulate that information is passed along indiscrete packets that cannot be diluted.(4) Any point in the process leads to many possible next steps, and where that next stepleads could be a surprise.(5) Science may involve many different people engaged in all sorts of different activities indifferent orders and at different points in time.D. (1) natural world (2) investigations (3) basic question(4) information (5) Experiments (6) detailed understanding(7) built upon (8) deepen and extend (9) in the process(10) testing (11) observation (12) new direction(13) in different orders (14) represent (15) less importantUnit 3 Ancient China’s Contribution to ScienceKeys to the ExercisesApproaching the Topic1. 1) Needham is the world’s famous Sinologist and author of Science and Civilization inChina.2) The European people just take these inventions for granted. All originated in China buthave long since been adopted by the West.3) They helped to inspire the European agricultural and industrial revolutions.4) It has won five literary awards in America and been translated into 43 languages.5) His book, The Spirit of Chinese Invention, was approved by the Chinese Ministry ofEducation for use in connection with the national secondary curriculum in China.2. 1) f 2) k 3) c 4) a 5) o 6) n 7) g 8) e 9) d 10) m 11) i 12) h 13) j 14) l 15) b4. (1) credit (2) considerable (3) befriended (4) breakthroughs (5) thoroughly(6) flown (7) academic (8) embark (9) suggested (10) staff6. 1) The overlooked great breakthroughs in ancient China.2)Dr. Needham argued that a proper book on the history of Chinese science and technologywould have a wide bearing on the general history of thought and ideas.3) He helped to bring due credit to China’s overlooked contribution to scientific innovation.4) Yes, he does. Because he believed that a proper popular book would have a wide bearing onthe general history of thoughts and ideas, which could not be possible if the book was tooacademic.Reading about the Topic3. 1) Both Westerners and Chinese people are ignorant of the fact that the West imported a lot ofinventions from ancient China.2) Because more than half of the basic inventions and discoveries upon which the“modernworld”rests come from China.3) Because they take many great achievements for granted, and even the Chinese themselveslost sight of the truth, so their western inheritors wouldn’t trouble themselves to know thetruth.4) Because it is always more satisfying to the ego to think that they have reached theirpresent position alone and unaided, and that they are the proud masters of all abilities andall crafts.4. Set 1: 1) d 2) e 3) a 4) b 5) c 6) g 7) f 8) hSet 2: 1) d 2) g 3) e 4) h 5) b 6) a 7) c 8) f 5. Para. A (e) Para. B (b) Para. C (f) Para. D (a)Para. E (a)Para. F (a) Para. G (c) Para. H (g) Para. I (h) Para. J (d)6. 1) The three inventions transform-ed completely the modern world and mark-ed it off fromthe ancient and the Middle Ages.2) The European agricultural revolution, which laid the basis for the Industrial Revolution,came about only because of the importation of Chinese ideas and inventions.3) The truth that half of the basic inventions and discoveries originated from China needs tobe imparted to schoolchildren. The purpose is to let them know the truth and then tobridge the chasm between the East and the West.4) The bureaucratic organization of China in its earlier stages strongly helped science togrow; only in its later ones did it inhibit further growth, and in particular prevented abreakthrough which has occurred in Europe.5) The author points out the reasons why China was developed in the past but backward atpresent and why the West was underdeveloped in the past but advanced at present.7. Set 1: 1) c 2) g 3) h 4) b 5) f 6) d 7) a 8) eSet 2: 1) c 2) d 3) g 4) e 5) a 6) b 7) f 8) h 8. 1) The two readings both list a series of great inventions and discoveries that originated inancient China. Reading 1 tends to be factual, while Reading 2 is more critical of the factthat the Chinese are ignorant of their ancient achievements and the Westerners simply takethem for granted.2) The argument in Reading 2 is more reasonable and acceptable since the author uses a lot ofexamples and examines the question from both the Chinese and Western perspectives toillustrate his point.3) Reading 2 holds more obvious negative attitudes towards Westerners.4) It would be better if the nations and the peoples of the world had a clearer understandingof each other, allowing the mental gap between Eastand West to be bridged. (Reading 2)The discoveries and inventions made in Europe in the seventeenth century and thereafterdepended so much in so many cases on centuries of previous Chinese progress in science,technology and medicine. (Reading 3)9. 1) He regarded the origins of these inventions as “obscure”and he died without everknowing that all of them were Chinese. (Para. B)2) Chauvinistic Westerners, of course, always try to minimize the indebtedness of Europe toChina in the ancient and the Middle Ages, but often the circumstantial evidence iscompelling. (Para. C)3) In many cases we simply cannot identify the channels through which knowledge wasconveyed from East to West. (Para. C)4) Modern science which developed in the seventeenth century was a mathematization ofhypotheses about nature, combined with experimentation. (Para. D)5) One factor which must have great relevance here isthe circumstance that the feudalism ofEurope and China were fundamentally different. (Para. E)10.The feudalism of China differed greatly from that of Europe in that its bureaucraticorganization promoted the growth of science in ancient China but inhibited its furtherdevelopment later on.Exploring the Topic4. 1) Increasingly being bewitched by the advanced European technology, the Chinese haveforgotten their own achievements.2) A book like that would be absolutely non-academic; it would nevertheless have afar-reaching influence on the general history of thought and ideas.3) The lesson to be drawn from the history of agriculture can best illustrate the ignorance ofthe egoistic westerners.4) The Chinese and Westerners are equally surprised when they realize that modernagriculture, modern shipping and even the essentialdesign of the steam engine alloriginated from China.5) A clear understanding among the nations and the peoples of the world would be welcomedto bridge the gap between East and West.5. 2) The deafening noise, and the glare of the engine fire, would have a bad effect on nerves.Further, being moved through the air at a high speed would do great injury to delicatelungs. The sudden plunging of a train into the darkness of a tunnel, and the equally suddenrush into full daylight, would cause great damage to the eyesight.3) What was it that enabled them to become great or successful? Were they born withsomething special? Or did their greatness have more to do with timing, devotion and,perhaps, an uncompromising personality? The answer is a never surrender attitude. If greatachievers share anything, it is an unrelenting drive to succeed. There is a tendency to thinkthat they are endowed with something super-normal.Integrated Exercises2. (1) insight (2) expertise (3) obscure (4) backward(5) undertake (6) ignorant (7) acknowledge (8) essential(9) minimize (10) shatter (11) fading (12) illustration 3.(1) insightful (2) transformation (3) respectively (4) dazzling (5) resurgent(6) indebted (7) backwards (8) irrelevant (9) unparalleled (10) illusionary4. (1) C (2) D (3) A (4) B (5) A (6) A (7) C (8)D (9) B (10) D5. (1) Examples will be drawn from literature and popular media to illustrate the range ofleadership and non-leadership behaviors and competencies.(2) You’ll never be able to eliminate interruptions altogether but you can do a lot to minimizethem.(3) There is evidence that the movie reinforces negative stereotypes about women.(4) The violence to property will do nothing to facilitate that investigation.(5) Determination and effort enable-d the young man to acquire success.(6) The project was held back by budget restraints.(7) We will continue to press governments in the region to undertake political reforms.(8) This level of economic growth is unprecedented and unique.(9) This policy could isolate the country from the other permanent members of the UnitedNations Security Council.(10) The profound economic effect would accumulate day by day, and much of it might bereversible.7. (1) It must be realized that China experienced a great transformation in the last century.(2) However, it is rather questionable whether the majority of Americans know the truthabout China and Chinese people.(3) All of the information can be conveyed by simple graphs.(4) It is essential that our children absorb this lesson into their outlook on the world.(5) It is a lesson that all of us should take to heart.(6) We must never lose sight of the fact that many inventions originated in China.(7) Many of us take it for granted that technology is the top priority in economicdevelopment.(8) How was it that you had the right information at the right place and at the right time?(9) I can think of no better illustration of the importance of higher education than the fact thatmany university graduates have become the leaders in various f ields.(10) The demand for a raise ref lects as much a desire for the recognition of their success asfor more money.8. A. (1) C (2) B (3) D (4) D (5) CB. China’s ancient great inventions and discoveries, as the forerunners of some of themodern technologies, both enhance the quality of human life and change Chinese historyof science. The most signif icant ones are papermaking, gunpowder, compass and printing.Paper, one of the most widely used and indispensable materials, led to subsequentinnovations like paper currency, woodblock printing and ceramic movable type printing.The most important invention of gunpowder triggered a series of related discoveries like。
experiment results和experimental results -回复问题并解释这两个术语之间的区别。
文章应包括以下内容:1. 引言:介绍实验结果和实验结果术语的重要性和使用范围。
2. 实验结果的定义:解释实验结果的含义和来源。
3. 实验结果的目的:描述实验结果的主要目的和用途。
4. 实验结果的组成部分:介绍实验结果的主要组成部分,如数据、图表和文字描述。
5. 实验结果的展示和解释:讨论如何展示和解释实验结果以便于理解和分析。
6. 实验结果的验证和重复性:解释实验结果的验证过程和重复性的重要性。
7. 实验结果与实验结果的区别:区分实验结果和实验结果术语之间的差异并解释其使用场景和含义。
8. 结论:总结实验结果和实验结果术语的重要性,并强调实验结果的有效展示和解释对于科学研究的重要性。
以下是一份参考文章:标题:实验结果和实验结果术语:定义、目的和区别的解释引言:实验结果和实验结果术语是科学研究中非常重要的概念。
它们帮助研究人员有效地记录、分析和解释实验数据,并为其他研究人员提供复制实验的基础。
在本文中,我们将探讨实验结果和实验结果术语的定义、目的以及它们之间的区别,并强调实验结果的有效展示和解释对于科学研究的重要性。
实验结果的定义:实验结果是指在科学实验中观察到的现象、测量到的数据或得出的结论。
这些结果可以通过各种方法获得,例如测量、观察、计算或实验操作的输出。
实验结果是研究人员根据实验过程的实际结果来描述和解释的数据,这些数据可以用于验证或推翻假设。
实验结果的目的:实验结果的主要目的是提供对实验得出的结论、观察或测量的描述和解释。
实验结果的目的是帮助其他研究人员理解实验过程中所观察到的现象,并在进一步的研究中重复实验。
此外,实验结果还可以用于验证或推翻原始假设,并为其他研究提供依据和参考。
实验结果的组成部分:实验结果通常由以下几个主要组成部分构成:1. 数据:实验数据是实验过程中记录的数值、测量结果或观察到的现象。
学术英语作文视听说2第二版课后答案Title: Academic English Writing and Listening Speaking 2 Second Edition Post-lesson AnswersIntroduction:Academic English Writing and Listening Speaking 2 is a comprehensive textbook designed to help students improve their academic English skills. In this document, we will provide the answers to the exercises at the end of each chapter in the second edition of the textbook.Chapter 1: Introduction to Academic English1. What are the key features of academic writing?Answer: The key features of academic writing include clarity, coherence, precision, and objectivity. Academic writing should be formal, structured, and based on evidence.2. Why is it important to use citations in academic writing?Answer: It is important to use citations in academic writing to give credit to the original source of ideas and information, to avoid plagiarism, and to provide evidence for arguments.Chapter 2: The Writing Process1. What are the steps in the writing process?Answer: The steps in the writing process include prewriting, drafting, revising, editing, and proofreading.2. How can brainstorming help you generate ideas for your writing?Answer: Brainstorming can help you generate ideas for your writing by allowing you to explore different perspectives, make connections between ideas, and identify key points to focus on.Chapter 3: Organizing Your Ideas1. What are some strategies for organizing your ideas in an academic paper?Answer: Some strategies for organizing your ideas in an academic paper include creating an outline, using topic sentences, and incorporating transitions between paragraphs.2. How can you effectively use evidence to support your arguments in academic writing?Answer: You can effectively use evidence to support your arguments in academic writing by citing credible sources, providing relevant examples, and analyzing and interpreting the evidence.Chapter 4: Developing Academic Vocabulary1. Why is it important to develop a range of academic vocabulary?Answer: It is important to develop a range of academic vocabulary to express ideas clearly and accurately, to understand complex texts, and to communicate effectively in academic settings.2. What are some strategies for learning and practicing academic vocabulary?Answer: Some strategies for learning and practicing academic vocabulary include reading academic texts, using a dictionary and thesaurus, and creating flashcards to study new words.Chapter 5: Understanding Academic Readings1. How can you improve your reading comprehension skills in academic texts?Answer: You can improve your reading comprehension skills in academic texts by previewing the text, identifying key ideas and main points, and making connections between the text and your own knowledge.2. What are some common reading strategies that can help you understand academic texts?Answer: Some common reading strategies that can help you understand academic texts include skimming, scanning, annotating, and summarizing the text.Chapter 6: Listening and Speaking Skills1. What are some strategies for improving your listening skills in academic settings?Answer: Some strategies for improving your listening skills in academic settings include focusing on key ideas, taking notes, and asking questions for clarification.2. How can you prepare for and participate in academic discussions and presentations?Answer: You can prepare for and participate in academic discussions and presentations by researching the topic, organizing your ideas, practicing your speaking skills, and actively engaging with others in the discussion.Conclusion:In conclusion, the exercises at the end of each chapter in Academic English Writing and Listening Speaking 2 providevaluable practice opportunities for students to enhance their academic English skills. By reviewing the answers to these exercises, students can reinforce their understanding of key concepts and improve their writing, reading, listening, and speaking skills in academic contexts.。
Experiment 2: Spectral Analysis of Signal HarmonicsPurpose and DiscussionThe purpose of this simulation is to demonstrate the characteristics of signalharmonics using the Spectrum Analyzer and Wattmeter. Pure sinusoidal waveforms represent themselves as a single vertical spectral line in the frequency versusamplitude domain. When distortion is introduced, harmonics appear at multiples of the fundamental or frequency of oscillation. Mathematically, the addition of power in mW of each harmonic to that of the fundamental frequency results in the reconstruction of the total waveform.Other waveforms such as square waves, triangle waves and sawtooth waves contain an infinite number of harmonics which, when added together, furnish the shape, amplitude and frequency of the signal. Whatever the overall signal characteristics, spectral analysis is essential in the study of its individual components. Spectral Analysis is used in Experiment 9 to dissect an amplitude modulated signal.A sawtooth wave is made up of an infinite number of periodic sinusoidal frequencies which are whole multiples of the fundamental frequency. As their order increases, their amplitude and power decreases. The Fourier series for a sawtooth wave is:For our rms harmonic voltage level calculations we will use the approximation:The fundamental frequency is:Although f 0 might represent the fundamental frequency of a square wave without the addition of its odd harmonics, f 0 is simply a sinusoidal wave. The second harmonic has a sinusoidal frequency of 3f 0. The third harmonic has a sinusoidal frequency of 5f 0. As each harmonic is added, the waveform looks more like a square wave. A perfect square wave is made up of an infinite number of odd harmonics.For example, if the fundamental frequency of a square wave is 1 kHz, 3f 0 = 3 kHz, 5f 0 = 5 kHz and 7f 0 = 7 kHz. The Fourier series for a square wave is:E A t t t t n =−+−+2122133144ωωωω(sin sin sin sin .....)E Amplitude n n =23πf period 01=τE A t t t t n =−+−+4133155177πωωωω(cos cos cos cos .....)6 Understanding RF Circuits with MultisimFor our rms harmonic voltage level calculations we will use the approximation:Since the amplitude of higher order harmonics is significantly smaller than that of the fundamental frequency, harmonics are generally only calculated to the 5th order.PartsResistor: 1 k ΩTest Equipment• Function Generator • Oscilloscope • Wattmeter•Spectrum AnalyzerFormulaePower in wattsP = V rms 2/ R L Equation 2-1Voltage in rms of nth order harmonic of a square waveEquation 2-2 rms = amplitude Equation 2-3Voltage in rms of nth order harmonic of a sawtooth waveEquation 2-4Equation 2-5E Amplituden n =42πE Amplitude n n =23πE Amplitude n n =42πrms amplitude =3Spectral Analysis of Signal Harmonics7 ProcedureFigure 2-11.Connect the circuit illustrated in Figure 2-1. Connect the Function Generator,Oscilloscope, Wattmeter and Spectrum Analyzer as shown. When connecting the Wattmeter, note that the side of the meter marked with V is connected in parallelwith the load and the right side is connected in series with the load.2.Double-click the Oscilloscope to view its display. Set the time base to 50 µs/Divand Channel 1 to 10 V/Div. Select Auto triggering and DC coupling.3.Double-click the Function Generator to view its display. Choose Frequency =10 kHz, Duty Cycle = 50%, Amplitude = 10 V and Offset = 0. Choose Squarewave.4.Double-click on the Spectrum Analyzer to view its display. Select Set Span.Choose Start = 10k, End = 100k and Amplitude = Lin. Click Enter.5.Start the simulation.6.Double-click the Oscilloscope and verify that the amplitude is 10 V.7.Double-click the Spectrum Analyzer. Move the vertical marker to the left side ofthe window and measure the frequency and amplitude of the fundamental 10 kHz signal. These values will be shown at the bottom left of the window. Calculate the associated power in mW, using equation 2-1.8.Calculate the expected rms voltage using equation 2-3. Calculate the expectedpower. Repeat measurements and calculations for the 3rd and 5th harmonics. Addthe power in mW of the fundamental, 3rd and 5th harmonics to calculate the totalpower. Verify your results by double-clicking on the Wattmeter. Record yourresults in Table 2-1.9.Double-click on the Function Generator and select the triangle waveform.8 Understanding RF Circuits with Multisim10.Observe the display on the Oscilloscope window.11.Double-click the Spectrum Analyzer and observe the display. Describe thespectrum including the location of the harmonics.12.Double-click on the Function Generator once more and select a duty cycle of80%. Observe the display on the Oscilloscope window noting the change in thewaveform.13.Double-click on the Spectrum Analyzer and observe the spectrum of a sawtoothwaveform.plete Table 2-2 for the sawtooth waveform.Expected OutcomeFigure 2-2 Frequency Spectrum of a 10 kHz Square waveSpectral Analysis of Signal Harmonics9 Data for Experiment 2MeasuredFrequency (Hz) Measured rmsVoltage (V)Measured Power(mW)Expected rmsVoltage (V)Expected Power(mW)f0f3f5Table 2-1 Square Wave Results Total Power in mW (measured)Total Power in mW from wattmeterMeasuredFrequency (Hz) Measured rmsVoltage (V)Measured Power(mW)Expected rmsVoltage (V)Expected Power(mW)f0f2f3Table 2-2 Sawtooth Wave ResultsTotal Power in mW (measured)Total Power in mW from wattmeterAdditional ChallengeDouble-click on the Function Generator. Select triangle wave at a frequency of 1 kHz, an amplitude of 5 V and a duty cycle of 50%. Repeat steps 2 to 5 for measured parameters.10 Understanding RF Circuits with Multisim。