Introduction To Wave Propagation Transmission Lines And Antennas

NONRESIDENT TRAINING COURSE SEPTEMBER 1998 Navy Electricity and Electronics Training Series Module 10—Introduction to Wave Propagation, Transmission Lines, and Antennas NAVEDTRA 14182 DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited Although the words “he,” “him,” and “his” are used sparingly in this course to enhance communication, they are not intended to be gender driven or to affront or discriminate against anyone DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited PREFACE By enrolling in this self-study course, you have demonstrated a desire to improve yourself and the Navy Remember, however, this self-study course is only one part of the total Navy training program Practical experience, schools, selected reading, and your desire to succeed are also necessary to successfully round out a fully meaningful training program COURSE OVERVIEW: To introduce the student to the subject of Wave Propagation, Transmission Lines, and Antennas who needs such a background in accomplishing daily work and/or in preparing for further study THE COURSE: This self-study course is organized into subject matter areas, each containing learning objectives to help you determine what you should learn along with text and illustrations to help you understand the information The subject matter reflects day-to-day requirements and experiences of personnel in the rating or skill area It also reflects guidance provided by Enlisted Community Managers (ECMs) and other senior personnel, technical references, instructions, etc., and either the occupational or naval standards, which are listed in the Manual of Navy Enlisted Manpower Personnel Classifications and Occupational Standards, NAVPERS 18068 THE QUESTIONS: The questions that appear in this course are designed to help you understand the material in the text VALUE: In completing this course, you will improve your military and professional knowledge Importantly, it can also help you study for the Navy-wide advancement in rate examination If you are studying and discover a reference in the text to another publication for further information, look it up 1998 Edition Prepared by FCC(SW) R Stephen Howard and CWO3 Harvey D Vaughan Published by NAVAL EDUCATION AND TRAINING PROFESSIONAL DEVELOPMENT AND TECHNOLOGY CENTER NAVSUP Logistics Tracking Number 0504-LP-026-8350 i Sailor’s Creed “I am a United States Sailor I will support and defend the Constitution of the United States of America and I will obey the orders of those appointed over me I represent the fighting spirit of the Navy and those who have gone before me to defend freedom and democracy around the world I proudly serve my country’s Navy combat team with honor, courage and commitment I am committed to excellence and the fair treatment of all.” ii TABLE OF CONTENTS CHAPTER PAGE Wave Propagation 1-1 Radio Wave Propagation 2-1 Principles of Transmission Lines 3-1 Antennas 4-1 APPENDIX I Glossary INDEX iii AI-1 INDEX-1 NAVY ELECTRICITY AND ELECTRONICS TRAINING SERIES The Navy Electricity and Electronics Training Series (NEETS) was developed for use by personnel in many electrical- and electronic-related Navy ratings Written by, and with the advice of, senior technicians in these ratings, this series provides beginners with fundamental electrical and electronic concepts through self-study The presentation of this series is not oriented to any specific rating structure, but is divided into modules containing related information organized into traditional paths of instruction The series is designed to give small amounts of information that can be easily digested before advancing further into the more complex material For a student just becoming acquainted with electricity or electronics, it is highly recommended that the modules be studied in their suggested sequence While there is a listing of NEETS by module title, the following brief descriptions give a quick overview of how the individual modules flow together Module 1, Introduction to Matter, Energy, and Direct Current, introduces the course with a short history of electricity and electronics and proceeds into the characteristics of matter, energy, and direct current (dc) It also describes some of the general safety precautions and first-aid procedures that should be common knowledge for a person working in the field of electricity Related safety hints are located throughout the rest of the series, as well Module 2, Introduction to Alternating Current and Transformers, is an introduction to alternating current (ac) and transformers, including basic ac theory and fundamentals of electromagnetism, inductance, capacitance, impedance, and transformers Module 3, Introduction to Circuit Protection, Control, and Measurement, encompasses circuit breakers, fuses, and current limiters used in circuit protection, as well as the theory and use of meters as electrical measuring devices Module 4, Introduction to Electrical Conductors, Wiring Techniques, and Schematic Reading, presents conductor usage, insulation used as wire covering, splicing, termination of wiring, soldering, and reading electrical wiring diagrams Module 5, Introduction to Generators and Motors, is an introduction to generators and motors, and covers the uses of ac and dc generators and motors in the conversion of electrical and mechanical energies Module 6, Introduction to Electronic Emission, Tubes, and Power Supplies, ties the first five modules together in an introduction to vacuum tubes and vacuum-tube power supplies Module 7, Introduction to Solid-State Devices and Power Supplies, is similar to module 6, but it is in reference to solid-state devices Module 8, Introduction to Amplifiers, covers amplifiers Module 9, Introduction to Wave-Generation and Wave-Shaping Circuits, discusses wave generation and wave-shaping circuits Module 10, Introduction to Wave Propagation, Transmission Lines, and Antennas, presents the characteristics of wave propagation, transmission lines, and antennas iv Module 11, Microwave Principles, explains microwave oscillators, amplifiers, and waveguides Module 12, Modulation Principles, discusses the principles of modulation Module 13, Introduction to Number Systems and Logic Circuits, presents the fundamental concepts of number systems, Boolean algebra, and logic circuits, all of which pertain to digital computers Module 14, Introduction to Microelectronics, covers microelectronics technology and miniature and microminiature circuit repair Module 15, Principles of Synchros, Servos, and Gyros, provides the basic principles, operations, functions, and applications of synchro, servo, and gyro mechanisms Module 16, Introduction to Test Equipment, is an introduction to some of the more commonly used test equipments and their applications Module 17, Radio-Frequency Communications Principles, presents the fundamentals of a radiofrequency communications system Module 18, Radar Principles, covers the fundamentals of a radar system Module 19, The Technician's Handbook, is a handy reference of commonly used general information, such as electrical and electronic formulas, color coding, and naval supply system data Module 20, Master Glossary, is the glossary of terms for the series Module 21, Test Methods and Practices, describes basic test methods and practices Module 22, Introduction to Digital Computers, is an introduction to digital computers Module 23, Magnetic Recording, is an introduction to the use and maintenance of magnetic recorders and the concepts of recording on magnetic tape and disks Module 24, Introduction to Fiber Optics, is an introduction to fiber optics Embedded questions are inserted throughout each module, except for modules 19 and 20, which are reference books If you have any difficulty in answering any of the questions, restudy the applicable section Although an attempt has been made to use simple language, various technical words and phrases have necessarily been included Specific terms are defined in Module 20, Master Glossary Considerable emphasis has been placed on illustrations to provide a maximum amount of information In some instances, a knowledge of basic algebra may be required Assignments are provided for each module, with the exceptions of Module 19, The Technician's Handbook; and Module 20, Master Glossary Course descriptions and ordering information are in NAVEDTRA 12061, Catalog of Nonresident Training Courses v Throughout the text of this course and while using technical manuals associated with the equipment you will be working on, you will find the below notations at the end of some paragraphs The notations are used to emphasize that safety hazards exist and care must be taken or observed WARNING AN OPERATING PROCEDURE, PRACTICE, OR CONDITION, ETC., WHICH MAY RESULT IN INJURY OR DEATH IF NOT CAREFULLY OBSERVED OR FOLLOWED CAUTION AN OPERATING PROCEDURE, PRACTICE, OR CONDITION, ETC., WHICH MAY RESULT IN DAMAGE TO 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Red, blue, and yellow Red, blue, and green Red, violet, and indigo Blue, green, and violet Space is less dense than glass Space is more dense than glass Glass reflects the light back to the source Glass refracts the light, causing the light to travel in all directions 1-40 What are the secondary colors of light? Orange, yellow, and blue-green Magenta, yellow, and cyan Purple, yellow, and black Red, white, and blue 1-46 If a light wave strikes a sheet of glass at a perpendicular angle, what is the effect, if any, on the light wave? 1-41 What causes sunlight to separate into different wavelengths and display a rainbow of colors when passed through a prism? The wave is completely absorbed The wave is reflected back toward the source The wave is refracted as it passes through the glass The wave is unchanged and continues in a straight line Refraction Reflection Dispersion Diffraction 1-42 The sun, gas flames, and electric light filaments are visible because they are 1-47 The amount of absorption of the light that strikes an object is determined by the object’s opaque transparent nonluminous self-luminous 1-43 Substances that transmit almost all of the light waves falling upon them possess which of the following properties? Opaqueness Transparence Translucence Self-lumination color purity density complexity 1-53 The electric field and magnetic field combine to form which of the following types of waves? 1-48 In a comparison of waves of light and sound as they travel from an air into water, how is the speed of (a) light waves and (b) sound waves affected? (a) Increased (a) Increased (a) Decreased (a) Decreased (b) increased (b) decreased (b) decreased (b) increased 1-54 The magnetic field radiated from an antenna is produced by what electrical property? 1-49 Which of the following waves are NOT a form of electromagnetic energy? 4 Heat waves Sound waves Light waves Radio waves color frequency visibility application Voltage lags current by 90 degrees Voltage leads current by 90 degrees Voltage and current are 180 degrees out of phase Voltage and current are in phase X-ray Radar Light Cosmic 1-52 Which of the following electronic devices is used to radiate and/or collect electromagnetic waves? Voltage Current Reactance Resistance 1-56 Applying rf energy to the elements of an antenna results in what phase relationship between voltage and current? 1-51 Which of the following portions of the frequency spectrum contains the highest frequency? Voltage Current Reactance Resistance 1-55 The electric field radiated from an antenna is produced by what electrical property? 1-50 The electromagnetic spectrum represents the entire range of electromagnetic waves arranged in the order of their Spherical Elliptical Electromagnetic Each of the above 1-57 What field exists close to the conductor of an antenna and carries the current? Antenna Receiver Transmitter Transmission line Electric Magnetic Induction Radiation 1-58 What field travels through space after being detached from the current-carrying rod of an antenna? Electric Magnetic Induction Radiation 1-59 Electric and magnetic fields on an antenna reach their maximum intensity at which of the following times? When they are a full cycle apart When they are three-quarter cycle apart When they are a half-cycle apart When they are a quarter-cycle apart ASSIGNMENT Textbook assignment: Chapter 2, “Radio Wave Propagation,” pages 2-1 through 2-47 _ 2-6 A frequency of 3.5 GHz falls into what rf band? 2-1 The induction field is made up of which of the following fields? E field only H field only Both E and H fields 2-2 After the radiation field leaves an antenna, what is the relationship between the E and H fields with respect to (a) phase and (b) physical displacement in space? (a) In phase (a) Out of phase (a) In phase (a) Out of phase 2-7 A radio wavelength expressed as 250 meters may also be expressed as how many feet? 410 820 1,230 1,640 (b) 90 degrees (b) 90 degrees (b) 180 degrees (b) 180 degrees 2-8 An increase in the frequency of a radio wave will have what effect, if any, on the velocity of the radio wave? 2-3 What is the first harmonic of a radio wave that has a fundamental frequency of 2,000 kHz? Increase Decrease None 6,000 kHz 2,000 kHz 3,000 kHz 4,000 kHz 2-9 An increase in frequency of a radio wave will have what effect, if any, on the wavelength of the radio wave? 2-4 In a radio wave with a fundamental frequency of 1.5 kHz, which of the following frequencies is NOT a harmonic? Increase Decrease None 6,000 kHz 5,000 kHz 3,000 kHz 4,000 kHz 2-10 What is the frequency, in kiloHertz, of a radio wave that is 40 meters long? 2-5 A radio wave with a frequency of 32 kHz is part of which of the following frequency bands? High Very high Super high Extremely high 75 750 7,500 75,000 The lf band The mf band The hf band The vhf band 2-11 What is the approximate wavelength, in feet, of a radio wave with a frequency of 5,000 kHz? 197 feet 1,970 feet 19,700 feet 197,000 feet 2-12 The polarity of a radio wave is determined by the orientation of (a) what moving field with respect to (b) what reference? (a) Electric (a) Electric (a) Magnetic (a) Magneti Figure 2-A.—Reflected radio waves IN ANSWERING QUESTION 2-15, REFER TO FIGURE 2-A (b) earth (b) antenna (b) antenna (b) earth 2-15 If the two reflected radio waves shown in the figure are received at the same instant at the receiving site, what will be the effect, if any, on signal quality? 2-13 Energy radiated from an antenna is considered horizontally polarized under which of the following conditions? A stronger signal will be produced A weak or fading signal will be produced The signal will be completely canceled out None If the wavefront is in the horizontal plane If the magnetic field is in the horizontal plane If the electric field is in the horizontal plane If the induction field is in the horizontal plane 2-16 The bending of a radio wave because of a change in its velocity through a medium is known as 2-14 The ability of a reflecting surface to reflect a specific radio wave depends on which of the following factors? Striking angle Wavelength of the wave Size of the reflecting area All of the above refraction reflection deflection diffraction 2-17 Radio communications can be diffracted to exceptionally long distances through the use of (a) what frequency band at (b) what relative power level? (a) Very low frequency (b) Low power (a) Very high frequency (b) Low power (a) Very low frequency (b) High power (a) Very high frequency (b) High power THIS SPACE LEFT BLANK INTENTIONALLY 2-23 A space wave (a) is primarily a result of refraction in what atmospheric layer and (b) extends approximately what distance beyond the horizon? 2-18 Electrically charged particles that affect the propagation of radio waves are found in what atmospheric layer? Troposphere Ionosphere Chronosphere Stratosphere (a) Ionosphere (b) One-tenth farther (a) Ionosphere (b) One-third farther (a) Troposphere (b) One-third farther (a) Troposphere (b) One-tenth farther 2-19 Most weather phenomena take place in which of the following region of the atmosphere? Troposphere Ionosphere Chronosphere Stratosphere 2-24 The signal of a space wave is sometimes significantly reduced at the receiving site because of which of the following interactions? 2-20 Radio wave propagation has the least effect because of its constancy on which of the following atmospheric layers? 4 Troposphere Ionosphere Chronosphere Stratosphere 2-25 For long-range communications in the hf band, which of the following types of waves is most satisfactory? 2-21 Long range, surface-wave communications are best achieved when the signal is transmitted over seawater with (a) what polarization at (b) what relative frequency? (a) Vertical (a) Vertical (a) Horizontal (a) Horizontal Sky wave Space wave Surface wave Reflected ground wave 2-26 Ionization in the atmosphere is produced chiefly by which of the following types of radiation? (b) Low (b) High (b) High (b) Low 2-22 The Navy’s long-range vlf broadcasts are possible because of the advantages of which of the following types of propagation? Space-wave refraction Space-wave reflections Ground-wave diffraction Ground-wave reflections Alpha radiation Cosmic radiation Infrared radiation Ultraviolet radiation 2-27 Ultraviolet waves of higher frequencies produce ionized layers at what relative altitude(s)? Diffraction Ionospheric refraction Repeated reflection and refraction Both and above Lower Higher Both and above 10 2-33 A 10-MHz wave entering the ionosphere at an angle greater than its critical angle will pass through the ionosphere and be lost in space unless which of the following actions is taken? 2-28 The density of ionized layers is normally greatest during which of the following periods? At night Before sunrise Between early morning and late afternoon Between afternoon and sunset 2-29 Compared to the other ionospheric layers at higher altitudes, the ionization density of the D layer is 2-34 The distance between the transmitter and the nearest point at which refracted waves return to earth is referred to as the about the same relatively low relatively high 2-30 What two layers in the ionosphere recombine and largely disappear at night? 4 C D E F No sky-wave Weak ground wave A zone of silence Strong ground wave 2-36 The greatest amount of absorption takes place in the ionosphere under which of the following conditions? 2-32 Refraction of a sky wave in the ionosphere is influenced by which of the following factors? skip distance return distance reception distance ground-wave distance 2-35 When ground-wave coverage is LESS than the distance between the transmitter and the nearest point at which the refracted waves return to earth, which of the following reception possibilities should you expect? D and F D and E E and F2 F1 and F2 2-31 For hf-radio communications covering long distances, what is the most important layer of the ionosphere? The ground wave is canceled The frequency of the wave is increased The frequency of the wave is decreased The ground wave is reinforced When sky wave intensity is the greatest When collision of particles is least When the density of the ionized layer is the greatest When precipitation is greatest Ionospheric density Frequency of the wave Angle of incidence of the wave All of the above 2-37 Which of the following layers provide the greatest amount of absorption to the ionospheric wave? 11 D and E D and F1 E and F1 F1 and F2 2-43 Which of the following ionospheric variation causes densities to vary with the axial rotation of the sun? 2-38 If the signal strength of an incoming signal is reduced for a prolonged period, what type of fading is most likely involved? 4 Selective Multipath Absorption Polarization 2-44 Which of the following ionospheric variation causes densities to vary with the position of the earth in its orbit around the sun? 2-39 Radio waves that arrive at a receiving site along different paths can cause signal fading if these waves have different velocities amplitudes phase relationships modulation percentages 2-40 The technique of reducing multipath fading by using several receiving antennas at different locations is known as what type of diversity? 4 Space Receiver Frequency Modulation Daily variation Seasonal variation 27-day sunspot cycle 11-year sunspot cycle 2-46 What relative range of operating frequencies is required during periods of maximum sunspot activity? Lower Medium Higher Angle of incidence Ground irregularities Frequency of the wave Each of the above 2-47 What factor significantly affects the frequency of occurrence of the sporadic-E layer? 2-42 Receiving sites located near industrial areas can expect to have exceptionally large losses in signal quality as a result of which of the following propagation situations? Daily variation Seasonal variation 27-day sunspot cycle 11-year sunspot cycle 2-45 Which of the following ionospheric variation causes densities to vary with the time of the day? 2-41 The amount of rf energy lost because of ground reflections depends on which of the following factors? Daily variation Seasonal variation 27-day sunspot cycle 11-year sunspot cycle Absorption Multihop refraction Natural interference Man-made interference 12 Seasons Latitude Weather conditions Ionospheric storms 2-53 The most consistent communications can be expected at which of the following frequencies? 2-48 What effect can the sporadic-E layer have on the propagation of sky waves? Causes multipath interference Permits long distance communications at unusually high frequencies Permits short-distance communications in the normal skip zone Each of the above 2-54 If the optimum working frequency for a communications link is 4,250 kHz, what is the approximate maximum usable frequency? 2-49 A sudden and intense burst of ultraviolet light is especially disruptive to communications in which of the following frequency bands? 4 Hf Mf Lf Vlf Antenna capabilities Weather conditions along the path of communication Density of ionized layers Presence of ionized layers D E F1 F2 2-56 At frequencies above 100 MHz, the greatest attenuation of rf energy from raindrops is caused by which of the following factors? 2-51 Which irregular variation in ionospheric conditions can cause a waiting period of several days before communications return to normal? 4 Sporadic E Ionospheric storms Sudden ionospheric disturbance Each of the above Ducting Heat loss Scattering Absorption 2-57 Under certain conditions, such as ducting, line-of-sight radio waves often propagate for distances far beyond their normal ranges because of which of the following factors? 2-52 For a radio wave entering the atmosphere of the earth at a given angle, the highest frequency at which refraction will occur is known by which of the following terms? 4,500 kHz 5,000 kHz 5,500 kHz 6,000 kHz 2-55 In determining the success of radio transmission, which of the following factors is the LEAST predictable? 2-50 The density of what ionosphere layer increases because of a violent eruption on the surface of the sun? Critical frequency Maximum usable frequency Maximum working frequency Optimum working frequency Usable frequency Refraction frequency Maximum usable frequency Optimum working frequency 13 Low cloud masses Ionospheric storms Temperature inversions Frequency fluctuations 2-62 Which of the following descriptions of tropospheric scatter signal reception is NOT true? 2-58 When ducting is present in the atmosphere, multihop refraction of line-of-sight transmission can occur because of which of the following factors? Receiver signal strength decreases as the turbulence height is increased The level of reception depends on the number of turbulences causing scatter The energy received is the portion of the wave reradiated by the turbulence Increased communications distance enables more turbulence to act on the signal, thereby raising the received signal level Operating frequency of the transmitter Height of the transmitting antenna Angle of incidence of the radio wave Each of the above 2-59 A propagation technique used to extend uhf transmission range beyond the horizon uses which of the following propagation characteristics? 2-63 The tropospheric scatter signal is often characterized by very rapid fading caused by which of the following factors? Ground reflection Ionospheric scatter Tropospheric scatter Atmospheric refraction 2-60 Communications by tropospheric scatter can be affected by which of the following conditions? Extreme path lengths Multipath propagation Turbulence in the atmosphere Angle of the transmitted beam Sunspot activity Atmospheric conditions Ionospheric disturbances All of the above 2-64 For which of the following communications situations would turbulence in the troposphere scatter transmission? 2-61 What effect, if any, does the radiation angle of a transmitting antenna have on the reception of communications by tropospheric scatter? 10 MHz, range 200 miles 30 MHz, range 800 miles 50 MHz, range 600 miles 100 MHz, range 400 miles The lower the angle, the weaker the signal The lower the angle, the stronger the signal The lower the angle, the more susceptible the signal is to distortion None 14 ASSIGNMENT Textbook assignment: Chapter 3, “Principles of Transmission Lines,” pages 3-1 through 3-58 _ 3-6 Uniform capacitance throughout the length of the line is an advantage of which of the following transmission lines? 3-1 A transmission line is designed to perform which of the following functions? Disperse energy in all directions Detune a transmitter to match the load Guide electrical energy from point to point Replace the antenna in a communications system 3-7 What is the primary advantage of a rigid coaxial line? 3-2 All transmission lines must have two ends, the input end and the output end What other name is given to the input end? 4 Sending end Generator end Transmitter end Each of the above input-gain rate input impedance output impedance voltage-gain ratio Load line Coaxial line Two-wire line Twisted-pair line I2R Inductor Dielectric Each of the above 3-10 Skin effect is classified as which of the following types of loss? 3-5 Electrical power lines are most often made of which of the following types of transmission lines? Metallic Dielectric Elliptical Cylindrical 3-9 To some degree, transmission lines always exhibit which of the following types of losses? 3-4 Which of the following lines is NOT a transmission medium? Low radiation losses Inexpensive construction Low high-frequency losses Each of the above 3-8 Which of the following wave-guides is seldom used because of its large energy loss characteristics? 3-3 A measurement of the voltage to current ratio (Ein/I in) at the input end of a transmission line is called the Coaxial line Twisted pair Shielded pair Two-wire open line Twin-lead line Shielded-pair line Two-wire open line Two-wire ribbon line 15 Copper Voltage Induction Dielectric 3-16 Leakage current in a two-wire transmission line is the current that flows through what component? 3-11 What transmission-line loss is caused by magnetic lines of force not returning to the conductor? 4 Copper Radiation Induction Dielectric 3-17 Conductance is the reciprocal of what electrical property? 3-12 What is the electrical wave-length of cycle if the frequency is 60 hertz? 125,000 meters 1,250,000 meters 5,000,000 meters 20,000,000 meters Inductance Resistance Capacitance Reciprocity 3-18 A transmission line that has current flowing through it has which, if any, of the following fields about it? 3-13 A transmission line 10 meters in length is considered to be electrically long at which of the following frequencies? 60 kilohertz 600 kilohertz megahertz 60 megahertz Electric field only Magnetic field only Both electric and magnetic fields None of the above 3-19 Maximum transfer of energy from the source to the transmission line takes place when what impedance relationship exists between the source and the transmission line? 3-14 The conductance value of a transmission line represents which of the following values? Expected value of current flow through the insulation Expected value of voltage supplied by the transmitter Value of the lump and distributed constants of the line divided by impedance Value of the lump and distributed constants of the line divided by impedance When the load impedance equals source impedance When the load impedance is twice the source impedance When the load impedance is half the source impedance When the load impedance is one-fourth the source impedance 3-20 The characteristic impedance (Z0) of a transmission line is calculated by using which of the following ratios? 3-15 Electrical constants in a transmission line are distributed in which of the following ways? The resistor The inductor The insulator The conductor Into a single device Along the length of the line According to the thickness of the line According to the cross-sectional area of the line 16 Rs to Rload of the line Imax to Imin at every point along the line E to I at every point along the line Ein to Eo of the line 3-26 The input impedance of a transmission line is affected by which of the following properties? 3-21 For a given voltage, what determines the amount of current that will flow in a transmission line? 4 Conductance Spacing of the wires Diameter of the wires Characteristic impedance 3-27 When a dc voltage is applied to a transmission line and the load absorbs all the energy, what is the resulting relationship between current and voltage? 3-22 When the impedance of a transmission line is measured, which of the following values frequently is NOT considered? Radiation loss Series inductance Parallel capacitance Each of the above Inductance Resistance Conductance Capacitance 3-23 The characteristic impedance of a long transmission line may be determined by using which of the following methods? They are in phase with each other They are equal to Z0 of the line They are out of phase with each other They are evenly distributed along the line 3-28 The initial waves that travel from the source to the load of a transmission line are referred to as what type of waves? Trial and error Calculating the impedance of the entire line Calculating the impedances at each end of the line Adding the impedances of successive short sections Incident Refracted Reflected Diffracted 3-29 Waves that travel from the output end to the input end of a transmission line are referred to as what type of waves? 3-24 When should lumped values for transmission-line constants be used to calculate characteristic impedance? When the line is short compared to one wavelength When the line is long compared to one wavelength When the line is infinitely long 3-25 In actual practice, the characteristic impedance of a transmission line is usually within which of the following resistance ranges? to 0.9 ohm to 49 ohms 50 to 600 ohms 601 to 1,000 ohms 17 Incident Refracted Reflected Diffracted 3-32 The instantaneous voltage on an infinite transmission line can be plotted against time by using which of the following instruments? A wavemeter A multimeter An oscilloscope A spectrum analyzer Figure 3-A.—Equivalent infinite transmission line 3-33 On an infinite transmission line with an ac voltage applied, which of the following is an accurate description of the effective voltage distribution along the line? IN ANSWERING QUESTION 3-30, REFER TO FIGURE 3-A 3-30 When a dc voltage is applied to the equivalent infinite line in the figure, which of the following conditions occurs along the length of the line? 4 Standing waves of voltage form Standing waves of current form Current flows indefinitely Voltage appears for a short time Voltage is at all points Voltage is constant at all points Voltage varies at a sine-wave rate Voltage varies at double the sine-wave rate 3-34 The velocity of propagation on a transmission line is controlled by which of the following line characteristics? Conductance Inductance only Capacitance only Capacitance and inductance 3-35 The total charge on a transmission line is equal to the current multiplied by which of the following factors? Figure 3-B.—Equivalent transmission line IN ANSWERING QUESTION 3-31, REFER TO FIGURE 3-B 3-31 Compared to a dc input, what relative amount of time is required for an ac input voltage to travel the length of the line shown in the circuit? Less Same More 18 Time Power Voltage Resistance 3-36 With only capacitance and inductance of the line given, the time (T) required for a voltage change to travel down a transmission line can be found by what formula? The characteristic impedance for an infinite transmission line can be figured using which of the following ratios? Figure 3-C.—Equivalent transmission line IN ANSWERING QUESTIONS 3-39 AND 3-40, REFER TO FIGURE 3-C ASSUME THAT THE LINE IS 1,200 FEET LONG A 150-FOOT SECTION IS MEASURED TO DETERMINE L AND C THE 150-FOOT SECTION HAS AN INDUCTANCE OF 0.36 MILLIHENRIES AND A CAPACITANCE OF 1,000 PICOFARADS 3-37 The characteristic impedance for an infinite transmission line can be figured using which of the following ratios? 3-39 What is the characteristic impedance of the line? Input current to velocity Input voltage to input current Input voltage to line resistance Input current to line resistance 3-38 The characteristic impedance of a transmission line can be figured by using which of the following formulas? 400 ohms 600 ohms 800 ohms 900 ohms 3-40 What is the velocity of the wave on the 150-foot section? 210,000,000 fps 225,000,000 fps 250,000,000 fps 275,000,000 fps 3-41 If a transmission line is open-ended, which of the following conditions describes its terminating impedance? 19 Finite Infinitely large Equal to load impedance Equal to source impedance ... soldering, and reading electrical wiring diagrams Module 5, Introduction to Generators and Motors, is an introduction to generators and motors, and covers the uses of ac and dc generators and motors... Module 9, Introduction to Wave- Generation and Wave- Shaping Circuits, discusses wave generation and wave- shaping circuits Module 10, Introduction to Wave Propagation, Transmission Lines, and Antennas, ... applied to light waves State the difference between sound waves and light waves 10 State the electromagnetic wave theory and list the components of the electromagnetic wave INTRODUCTION TO WAVE PROPAGATION