Electronics Technician/Volume 7/Assignment Questions

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Appendix II
Electronics Technician, Volume 7 - Antennas and Wave Propagation
US Navy
Assignment Questions
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​

Assignment Questions





Information: The text pages that you are to study are
provided at the beginning of the assignment questions.




​

ASSIGNMENT 1

Textbook Assignment; "Wave Propagation," chapter 1, pages 1-1 through 1-14.

1-1. Which of the following factors can affect atmospheric conditions?

  1. Geographic height
  2. Geographic location
  3. Changes in time
  4. All of the above

1-2. In what portion. of the atmosphere does the majority of weather phenomena take place?

  1. Ionosphere
  2. Stratosphere
  3. Troposphere
  4. Hydrosphere

1-3. Because the stratosphere is a relatively calm region with little or no temperature change, it will have almost no effect on radio wave propagation.

  1. True
  2. False

1-4. Variations in the ionosphere ionosphere can be separated into how many classes?

  1. regular variations
  2. irregular variations
  3. both 1 and 2 above
  4. seasons

1-5. The regular variations in the ionosphere can be seperated into how many classes?

  1. One
  2. Two
  3. Three
  4. Four

1-6. In ionization, when an electron is knocked free from a neutral gas atom, what is the overall charge of the atom?

  1. Negative
  2. Positive
  3. Neutral
  4. Inverted

1-7. The frequency of ultraviolet light passing through the atmosphere has what relationship to the ionospheric layer it ionizes?

  1. It is inversely proportional
  2. It is directly proportional
  3. It is inversely proportional during the day and directly proportional at night
  4. It is directly proportional during the day and inversely proportional at night

1-8. What term best describes the process that returns positive resulting from changes in the ions to their original neutral sun’s activity are known as state?

  1. Refraction
  2. Recombination
  3. Ionization
  4. Polarization

1-9. At what approximate time of day is the density of the ionospheric layers at its lowest level?

  1. Just before sunrise
  2. Mid-morning
  3. Afternoon
  4. Sunset

1-10 How many distinct layers make up the ionosphere?

  1. One
  2. Two
  3. Three
  4. Four

​1-11. At what frequencies does the combination of the earth's surface and. the D layer act as a waveguide?

  1. Vlf
  2. Lf
  3. Mf
  4. Hf

1-12. The D layer loses its 1-18 absorptive qualities at frequencies above what level?

  1. 30 MHZ
  2. 20 MHZ
  3. 10 MHZ
  4. 3 MHZ

1-13. What is the approximate range of the E layer above the earth's surface?

  1. 30-54 miles
  2. 55-90 miles
  3. 91-130 miles
  4. 131-160 miles

1-14. Frequencies above what level pass through the E layer unaffected?

  1. 50 MHZ
  2. 100 MHZ
  3. 150 MHZ
  4. 200 MHZ

1-15. During daylight hours, the F layer will divide into how many separate layers?

  1. Five
  2. Two
  3. Three
  4. Four

1-16. Most high-frequency, long-range communications occur in what layer(s) of the ionosphere?

  1. D
  2. E
  3. F
  4. H

1-17. Which. of the following is NOT a factor for radio wave refraction?

  1. Ionization density of the layer
  2. Frequency of the radio wave
  3. Angle of incidence
  4. Transmitter power

1-18. For any given ionized layer, the critical frequency is just below the escape point.

  1. True
  2. False

1-19. The critical angle for radio wave propagation depends on what two factors?

  1. Angle of incidence and layer density only
  2. Layer density and wavelength only
  3. Angle of incidence and wavelength only
  4. Wavelength and antenna height only

1-20. What term best describes the area located between the transmitting antenna and the point where the sky wave first returns to the earth?

  1. Ground
  2. Skip zone
  3. Skip distance
  4. Ace area

1-21. Which of the following factors will affect the outer limits of the skip zone?

  1. Frequency
  2. Sunspot activity
  3. Angle of transmission
  4. All of the above

1-22. Radio waves reflecting from the earth's surface or the ionosphere, 180 degrees out of phase, have what effect, if any, at the receiving station?

  1. The signal will be weak or faded
  2. The signal will be stronger
  3. The signal will be garbled
  4. None

​1-23. For ionospheric reflection to occur, the ionized layer must not be thicker than. how many wavelengths of the transmitted frequency?

  1. One
  2. Two
  3. Three
  4. Four

1-24. The ability of radio waves to turn sharp corners and bend around obstacles is known as

  1. reflection
  2. refraction
  3. diffraction
  4. waveshaping

1-25. Which of the following definitions best describes a shadow zone?

  1. The area of complete coverage at vlf frequencies
  2. The area within the diameter of an obstruction
  3. The area ranging the height of the obstruction
  4. The area on the opposite side of the obstruction, in line-of-site from the transmitter to the receiver

1-26. What type of fading occurs for the longest amount of time?

  1. Phase shift
  2. Absorption
  3. Multipath
  4. Diffraction

1-27. Which of the following are examples of multipath radio wave transmissions?

  1. Groundwaves
  2. Ionospheric refractions
  3. Reflection from the earth's surface
  4. All of the above

1-28. Fading on the majority of the ionospheric circuits is a result of what particular type fading?

  1. Selective
  2. Absorption
  3. Multipath
  4. Weather

IN ANSWERING QUESTIONS 1-29 AND 1-30, SELECT FROM THE FOLLOWING LIST THE DEFINITION OF THE INDICATED TERM.

A. Two or more receiving antennas spaced apart to produce a usable signal

B. Two or more receiving antennas of varying heights located together

C. The use of two separate transmitters and receivers on different frequencies transmitting the same information

D. The use of two separate transmitters and receivers on the same frequency transmitting the same information

1-29. Space diversity.

  1. A
  2. B
  3. C
  4. D

1-30. Frequency diversity.

  1. A
  2. B
  3. C
  4. D

1-31. A. wide band of frequencies is transmitted and selective fading occurs. Which of the following statements best describes the effect of the fading on the signal?

  1. It affects various frequencies
  2. It can cause changes in phase and amplitude
  3. It can cause severe distortion and limit total signal strength
  4. All of the above

Which ionospheric layer is most dense during the winter?

  1. E
  2. D
  3. F2
  4. F1

​1-33. During the 27-day sunspotcycle, which ionospheric layer experiences the greatest fluctuations in density?

  1. D
  2. E
  3. F1
  4. F2

IN ANSWERING QUESTIONS 1-34 THROUGH 1-38, SELECT FROM THE FOLLOWING LIST THE DEFINITION OF THE INDICATED TERM.

A. Depends on the angle of the sun; refracts hf waves during the day, up to 20 MHz, to distances of 1200 miles; greatly reduced at night
B. Reflects vlf waves for long-range communications; refracts If and. mf for short-range communications; has little effect on. vhf and above; gone at night
C. Density depends on the angle of the sun; its main effect is absorption of hf waves passing through to the F2 layer
D. Provides long-range hf communications; very variable; height and density change with time of day, season, and sunspot activity
E. Structure and density depend. on the time of day and the angle of the sun; consists of one layer at night and two layers during the day

1-34. D layer.

  1. A
  2. B
  3. C
  4. D

1-3. E layer

  1. A
  2. B
  3. C
  4. D

1-36. F layer

  1. B
  2. C
  3. D
  4. E

1-37. F1 layer

  1. A
  2. B
  3. C
  4. D

1-38. F2 layer

  1. A
  2. C
  3. D
  4. E

1-39. During periods of maximum sunspot activity within the eleven-year cycle, critical frequencies for all layers increase.

  1. True
  2. False

1-40. Which of the following problems is NOT a negative side effect of the sporadic E layer?

  1. Causes increased multipath problems
  2. Provides additional absorption
  3. Blanks out more favorable layers
  4. Increased static in line of sight communications

1-41. When sudden ionospheric disturbances (SID) occurs, which ionospheric layer is affected the most?

  1. D
  2. E
  3. F1
  4. F2

1-42. What effect do ionospheric storms have on (a) the range of frequencies and (b) the working frequency used for communications?

  1. (a) Increase (b) increase
  2. (a) Decrease (b) decrease
  3. (a) Increase (b) decrease
  4. (a) Decrease (b) increase

​1-43. What form of precipitation has the greatest absorption effect on RF energy?

  1. Fog
  2. Snow
  3. Rain
  4. Hail

1-44. The duct effect produced by temperature inversion allows for long—distance communications over what frequency band?

  1. Vlf
  2. Lf
  3. Hf
  4. Vhf

1-45. Which of the following factors affect(s) the amount of ground reflection loss when a radio wave is reflected from the earth's surface?

  1. Angle of incidence
  2. Ground irregularities
  3. Electrical conductivity at the point of reflection
  4. All of the above

1-46. As an RF wave increases in distance, the wavefront spreads out, reducing the amount of energy available within any given. unit of area. This action produces what type of energy loss?

  1. Absorption
  2. Ground reflection
  3. Freespace
  4. Spread

1-47. Radio waves above the MUF will experience what effect when refracted from the ionosphere?

  1. They will fall short of the desired location
  2. They will overshoot the desired location
  3. They will be absorbed by lower layers
  4. They will experience multipath fading

1-48. Variations in the ionosphere may change a preexisting muf. This is especially true because of the volatility of which of the following layers?

  1. F1
  2. F2
  3. D
  4. E

1-49. Radio waves that are propagated below the LUF are affected by what problem(s)?

  1. Increased absorption
  2. Higher levels of atmospheric noise
  3. Higher rate of refraction
  4. All of the above

1-50. The frequency that will avoid the problems of multipath fading, absorption, noise, and rapid changes in the ionosphere is known by what term?

  1. LUF
  2. MUF
  3. FOT
  4. LOS
​

ASSIGNMENT 2

Textbook Assignment: "Antennas," chapter 2, pages 2-1 through 2-32.

2-1 Electromagnetic radiation from an antenna is made up of what two components?

  1. E and. H fields
  2. Ground and sky waves
  3. Vertical and horizontal wavefronts
  4. Reflected and refracted energy

2-2. What determines the size of a transmitting antenna?

  1. Transmitter power
  2. Available space
  3. Operating frequency
  4. Distance to be transmitted

2-3. Most practical transmitting antennas are divided into two classifications, Hertz and Marconi.

  1. T
  2. F

2-4. Hertz antennas are designed to operate at what wavelength in relationship to their operating frequency?

  1. Quarter-wave
  2. Half-wave
  3. Three quarter-wave
  4. Full-wave

2-5. Marconi antennas are used for operating frequencies below what level?

  1. 10 MHz
  2. 6 MHz
  3. 4 MHz
  4. 2 MHz

2-6. All antennas regardless of their shape or size have how many basic characteristics?

  1. 1
  2. 2
  3. 3
  4. 4


2-7 The ability to use the same antenna for both transmitting and receiving is known by what term?

  1. Gain
  2. Reciprocity
  3. Directivity
  4. Polarization

2-8. The ability of an antenna or or more specific array to focus energy in one directions is represented by a measurement of what antenna property?

  1. Signal Strength
  2. Reciprocity
  3. Directivity
  4. Polarization

2-9. The gain of a transmitting antenna is 9 dB, what will the gain be for the same antenna used for receiving?

  1. 9 dB
  2. 6 dB
  3. 4 dB
  4. 3 dB

2-10. Which, if any, of the following components of a radiated electromagnetic field determines its direction of polarization?

  1. H lines
  2. E lines
  3. Angle of Propagation
  4. None of the above

2-11. Over long distances the polarization of a radiated wave changes, at what frequencies will this change be the most dramatic?

  1. VLF
  2. LF
  3. MF
  4. HF

​2-12. A transmitting antenna at ground level should be polarized in what manner to achieve best signal strength?

  1. Horizontally
  2. Vertically
  3. Circularly
  4. Linearly

2-13. What term describes the distance a wave travels during the period of one cycle?

  1. Wavelength
  2. Frequency
  3. Travel time
  4. Radiation rate

IN ANSWERING QUESTIONS 2-14 AND 2-15, REFER TO FIGURE 2-4 OF THE TEXT.

2-14. The points of high current and voltage are best described by which of the following terms?

  1. Peaks
  2. Crescents
  3. Loops
  4. Highs

2-15. The points of minimum voltage and minimum current are represented by which of the following terms?

  1. Lows
  2. Valleys
  3. Descents
  4. Nodes

2-16. An antenna at resonance will transmit at maximum efficiency; an antenna that is not at resonance will lose power in which of the following ways?

  1. Skin effect loss
  2. Heat loss
  3. Ground absorption
  4. Wave scattering

2-17. An antenna that radiates energy in all directions is said to have what type of radiation pattern?

  1. Isotropic
  2. Anisotropic
  3. Bysotropic
  4. Circumstropic

2-18. An antenna that radiates energy more strongly in one direction than another is said to have what type of radiation pattern?

  1. Isotropic
  2. Anisotropic
  3. Bysotropic
  4. Circumstropic

2-19. When viewing a radiation pattern graph, you can expect the areas of maximum and minimum radiation be identified by which of the following terms?

  1. High and low probes
  2. Maximum and minimum points
  3. Major and minor lobes
  4. Positive and negative lobes

2-20. If an antenna. is too short for the wavelength being used, what electrical compensation must be introduced for the antenna to achieve resonance?

  1. Lumped resistance
  2. Lumped capacitive reactance
  3. Lumped inductive reactance
  4. More power

2-21. If an antenna is too long for the wavelength being used, what electrical compensation must be introduced for the antenna to achieve resonance?

  1. Lumped resistance
  2. Lumped capacitive reactance
  3. Lumped inductive reactance
  4. Less power

2-22. A ground screen is a series of conductors buried 1 or 2 feet below the surface in a radial pattern and is usually of what length in comparison to the wavelength being used?

  1. One-quarter wavelength
  2. One-half wavelength
  3. Three-quarter wavelength
  4. Full wavelength

​2-23. When would a counterpoise be used?

  1. When easy access to the antenna base is necessary
  2. When the surface below is solid rock
  3. When the surface below is sandy ground
  4. All the above

2-24. Capacitive top-loading helps to increase which of the following antenna characteristics?

  1. Bandwidth
  2. Power-handling
  3. Directivity
  4. Radiation efficiency

2-25. What is the most limiting characteristic of the Yagi antenna?

  1. Power-handling
  2. Narrow bandwidth
  3. Physical size
  4. Lack of directivity

2-26. In general, log-periodic antennas have which of the following characteristics?

  1. Medium power handling capabilities
  2. High gain
  3. Extremely broad bandwidth
  4. All the above

2-27. A typical vertical monopole log periodic antenna designed to cover a frequency range of 2 to 30 MHz will require approximately how many acres of land for its ground plane system?

  1. 1 acre
  2. 2 acres
  3. 3 acres
  4. 4 acres

2-28. A sector log-periodic array can act as an antenna for a minimum of what number of transmit or receive systems?

  1. 1
  2. 2
  3. 3
  4. 4

2-29. The most distinct advantage of the rotatable log-periodic antenna is its ability to perform what function?

  1. Rotate 360 degrees
  2. Rotate from horizontal to vertical and back
  3. Ability to handle high transmitter power
  4. Ability to produce high antenna gain

2-30. What is the average power handling capability of an Inverted Cone antenna?

  1. 20 kw
  2. 30 kw
  3. 40 kw
  4. 50 kw

2-31. What determines the gain and directivity of a Rhombic antenna?

  1. Transmitter power
  2. Antenna height
  3. Radiated wave interaction
  4. Transmitted frequency

2-32. Most Whip antennas require some kind of a tuning system to improve bandwidth and power handling capabilities.

  1. T
  2. F

Why are UHF and. VHF antennas on board ship installed as high as possible?

  1. To prevent radiation hazard to personnel
  2. To prevent radiation hazard to ordinance
  3. To increase power handling capabilities
  4. To prevent unwanted directivity in the radiation pattern from mast structures

2-34. The central feed section for both the biconical and center-fed dipole are protected by what type of covering?

  1. SCOTCHCOAT
  2. RTV
  3. Laminated fiberglass
  4. Rubber shield

​2-35. The adjustable stub on the AS-390/SRC uhf antenna is used to adjust what antenna characteristic?

  1. The counterpoise angle
  2. The input impedance
  3. The radiation angle
  4. The feed point

2-36. The OE-82B/WSC-I(V) antenna group uses what type of polarization?

  1. Vertical
  2. Horizontal
  3. Right-hand circular
  4. Left-hand circular

2-37. The AN/WSC-S (V) shore station antenna consists of what number of OE-82A/WSC-1 (V) assemblies?

  1. 1
  2. 2
  3. 3
  4. 4

2-38. What does the acronym LPI stand for?

  1. Low power interference
  2. Low probability of intercept
  3. Low phase intercept
  4. Last pass intercept

2-39. The reflectors for the AN/WSC-6 (V) are mounted on three-axis pedestals and provide auto tracking using what scanning technique?

  1. Conical
  2. Peripheral
  3. Vertical
  4. Horizontal

2-40. Antenna tuning is accomplished using what piece or pieces of equipment?

  1. Couplers
  2. Tuners
  3. Multicouplers
  4. All the above

2-41. Antenna multicouplers are used to match more than one transmitter or receiver to what number of antennas?

  1. 1
  2. 2
  3. 3
  4. 4

2-42. The AN/URA-38 antenna coupler is an automatic tuning system primarily used with which radio transmitter?

  1. AN/WSC-3
  2. AN/URT-23
  3. AN/URC-8O
  4. AN/FRT-84

2-43. The AN/SRA-57 coupler group operates in which of the following frequency ranges?

  1. 2-6 Mhz
  2. 4-12 Mhz
  3. 10-30 Mhz
  4. 40-60 Mhz

2-44. How many channels are provided with the AN/SRA-12 multicoupler?

  1. 4
  2. 5
  3. 6
  4. 7

2-45. What type of radar would use a truncated paraboloid reflector that has been rotated 90 degrees?

  1. A surface search
  2. An air search
  3. A navigation
  4. A height-finder

2-46. Of the following methods, which is NOT used to feed a cylindrical paraboloid reflector?

  1. A linear array of dipoles
  2. A slit in the side of a waveguide
  3. A thin waveguide radiator
  4. A quarter-wave stub

​2-47. The elements of a broadside array are spaced one—half wavelength apart and are spaced how many wavelengths away from the reflector?

  1. One—eighth
  2. One—quarter
  3. One—half
  4. Three—quarter

2-48. What is the advantage, if any, to offsetting a feedhorn radiator for a parabolic dish?

  1. A broader beam angle
  2. The elimination of shadows
  3. A narrower beam angle
  4. No advantage

2-49. What is the range in nautical miles of the AN/GPN-27 radar?

  1. 55
  2. 75
  3. 105
  4. 155

2-50. What is the purpose of the jackscrew on the AS-3263/SPS-49(V) antenna?

  1. To adjust the beam width
  2. To vary the antenna feed horn focal distance
  3. To adjust the beam elevation angle
  4. To lockdown the antenna for PM

2-51. The OE-172/SPS-55 antenna normally operates in the linearly polarized mode, for what reason. would you use the circular polarized mode?

  1. To compensate for the ships pitch and roll
  2. To prevent jamming
  3. To reduce return echoes from precipitation
  4. To achieve over the horizon coverage

2-52. Which of the following is NOT a mode of operation. for the AN/SPN-35A radar set?

  1. Final
  2. Dual
  3. Surveillance
  4. Simultaneous

2-53. The two primary safety concerns associated with rf fields are rf burns and injuries caused by dielectric heating.

  1. T
  2. F

2-54. When a person. is standing in an rf field, power in excess of what level will cause a noticeable rise in body temperature?

  1. 5 milliwatts
  2. 10 milliwatts
  3. 15 milliwatts
  4. 20 milliwatts

2-55. When working aloft, what safety precaution(s) must be followed?

  1. Tag out the antenna at the switchboard to prevent it from becoming operational
  2. Secure motor safety switches for rotating antennas
  3. Wear the proper oxygen breathing apparatus when working near a stack
  4. All the above
​

ASSIGNMENT 3

Textbook Assignment: "Transmission Lines and Waveguides," chapter 3, pages 3-1 through 3-32.

3-1. A transmission line is designed to perform which of the following functions?

  1. Disperse energy in all directions
  2. Detune a transmitter to match the load
  3. Guide electrical energy from point to point
  4. Replace the antenna in a communications system

3-2. The conductance value of a transmission line represents which of the following values?

  1. Expected value of current flow through the insulation
  2. Expected value of voltage supplied by the transmitter
  3. Value of the lump and distributed constants of the line divided by impedance
  4. Value of the lumped constants of the line as seen by the source and the load

3-3. Distributed constants in a transmission line are distributed in which of the following ways?

  1. Between ground and any single point on the line
  2. Along the length of the line
  3. According to the thickness of the line
  4. According to the cross-sectional area of the line

3-4. Leakage current in a two-wire transmission line is the current that flows through what component?

  1. The resistor
  2. The inductor
  3. The insulator
  4. The conductor

3-5. Conductance is the reciprocal of what electrical property?

  1. Inductance
  2. Resistance
  3. Capacitance
  4. Reciprocity

3-6. A transmission line that has current flowing through it has which of the following fields about it?

  1. Electric only
  2. Magnetic only
  3. Both electric and magnetic
  4. Capacitive

3-7. A measurement of the voltage to current ratio (EinIout at the input end of a transmission ine is called the

  1. input-gain. rate
  2. voltage-gain ratio
  3. output impedance
  4. input impedance

3-8. The characteristic impedance (2.) of a transmission. line is calculated by using which of the following ratios?

  1. Rsource to Rload of the line
  2. Imax to Imin at every point along the line
  3. E to I at every point along the line
  4. Ein to Eout of the line

​3-9. 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?

  1. When the load impedance equals the source impedance
  2. When the load impedance is twice the source impedance
  3. When the load impedance is half the source impedance
  4. When the load impedance is one-fourth the source impedance

3-10. Which of the following sets of terms represents a type of loss in a transmission line?

  1. I2R and induction only
  2. Induction and dielectric only
  3. Dielectric and radiation only
  4. I2R, induction, and dielectric

3-11. Skin effect is classified as which of the following types of loss?

  1. Copper
  2. Voltage
  3. Induction
  4. Dielectric

3-12. What transmission—line loss is caused by magnetic lines of force not returning to the conductor?

  1. Copper
  2. Radiation
  3. Induction
  4. Dielectric

3-13. 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?

  1. They are in phase with each other
  2. They are equal to Zo the line
  3. They are out of phase with each other
  4. They are evenly distributed along the line

3-14. The initial waves that travel from the generator to the load of a transmission line are referred to as what type of waves?

  1. Incident
  2. Refracted
  3. Reflected
  4. Diffracted

3-15. Waves that travel from the output end to the input end of a transmission line are referred to as what type of waves?

  1. Incident
  2. Refracted
  3. Reflected
  4. Diffracted

3-16. The ratio of maximum voltage to minimum voltage on a transmission line is referred to as the

  1. rswr
  2. pswr
  3. vswr
  4. iswr

3-17. Which of the following ratios samples the magnetic field along a line?

  1. Vszr
  2. Pswr
  3. Iswr
  4. Rswr

3-18. Which of the following lines is NOT a transmission medium?

  1. Load line
  2. Coaxial line
  3. Two—wire open line
  4. Twisted—pair line

3-19. Electrical power lines are most often made of which of the following types of transmission lines?

  1. Twin—lead line
  2. Shielded—pair line
  3. Two—wire open line
  4. Two—wire ribbon line

​3-20. Uniform capacitance throughout the length of the line is an advantage of which of the following transmission lines?

  1. Coaxial line
  2. Twisted pair
  3. Shielded pair
  4. Two—wire open line

3-21. What is the primary advantage of a rigid coaxial line?

  1. Low radiation losses
  2. Inexpensive construction
  3. Low high—frequency losses
  4. Easy maintenance

3-22. The most efficient transfer of electromagnetic energy can be provided by which of the following mediums?

  1. Waveguides
  2. Twin-lead flat lines
  3. Single-conductor lines
  4. Coaxial transmission lines

3-23. Copper I2R losses are reduced by what physical property of waveguides?

  1. Small surface area
  2. Large surface area
  3. Shape of the waveguides
  4. Waveguide material being used

3-24. In a coaxial line, the current—carrying area of the inner conductor is restricted to a small surface layer because of which of the following properties?

  1. Skin effect
  2. Copper loss
  3. Conductor density
  4. Waveguide material beingused

3-25. Which of the following dielectrics is used in waveguides?

  1. Air
  2. Mica
  3. Insulating oil
  4. Insulating foam

3-26. Which of the following characteristics of a waveguide cause its lower—frequency limitation?

  1. I2R loss
  2. Physical size
  3. Wall thickness
  4. Dielectric loss

3-27. At very high frequencies, ordinary insulators in a two—wire transmission line display the characteristics of what electrical component?

  1. An inductor
  2. A resistor
  3. A capacitor
  4. A transformer

3-28. At high frequencies, which of the following devices works best as an insulator?

  1. An open half—wave section
  2. An open quarter—wave section
  3. A shorted half—wave section
  4. A shorted quarter—wave section

3-29. The range of operating frequencies is determined by which of the following waveguide dimensions?

  1. The widest (height/width)
  2. The narrowest (height/width)
  3. The shortest (length)
  4. The longest (length)

3-30. The cutoff frequency for a waveguide is controlled by the physical dimensions of the waveguide and is defined as the frequency at which two quarter wavelengths are

  1. shorter than the "a" dimension
  2. shorter than the "b" dimension
  3. longer than the "a" dimension
  4. longer than the "b" dimension

​3-31. In practical applications, which of the following dimensions describes the wide dimension of the waveguide at the operating frequency?

  1. 0.1 wavelength
  2. 0.2 wavelength
  3. 0.5 wavelength
  4. 0.7 wavelength

3-32. Which of the following fields is/are present in waveguides?

  1. E field only
  2. H field only
  3. E and. H fields
  4. Stationary fields

3-33. A difference in potential across a dielectric causes which of the following fields to develop?

  1. Electric only
  2. Magnetic only
  3. Electromagnetic

3-34. H lines have which. of the following distinctive characteristics?

  1. They are continuous straight lines
  2. They are generated by voltage
  3. They form closed loops
  4. They form only in the waveguide

3-35. For an electric field to exist at the surface of a conductor, the field must have what angular relationship to the conductor?

  1. 0°
  2. 30°

3 45° 4 90°

3-36. If the wall of a waveguide is perfectly flat, the angle of reflection is equal to which of the following angles?

  1. Cutoff
  2. Incidence
  3. Refraction
  4. Penetration

3-37. The cutoff frequency in a waveguide occurs at exactly what angle of reflection?

  1. 10°
  2. 30°
  3. 45°
  4. 90°

3-38. How does the group velocity of an electromagnetic field in a waveguide compare to the velocity of a wavefront through free space?

  1. Group velocity is somewhat faster
  2. Group velocity is somewhat slower
  3. Group velocity is twice that of free velocity
  4. Free velocity is twice that of group velocity

3-39. The group velocity of a wavefront in a waveguide may be increased by which of the following actions?

  1. Decreasing the frequency of the input energy
  2. Increasing the frequency of the input energy
  3. Increasing the power of the input energy
  4. Decreasing the power of the input energy

3-40. The various field configurations that can exist in a waveguide are referred to as

  1. wavefronts
  2. modes of operation
  3. fields of operation
  4. fields of distribution

3-41. The most efficient transfer of energy occurs in a waveguide in what mode?

  1. Sine
  2. Dominant
  3. Transverse
  4. Time-phase

​3-42. How is the cutoff wavelength for a circular waveguide computed?

  1. 1.17 times the radius of the waveguide
  2. 1.17 times the diameter of the waveguide
  3. 1.71 times the diameter of the waveguide
  4. 1.71 times the radius of the waveguide

3-43. The field configuration in waveguides is divided into what two categories?

  1. Half-sine and dominant
  2. Transverse electric and transverse magnetic
  3. Transverse electric and dominant
  4. Transverse magnetic and half-sine

3-44. With a mode description of TE1,0, what maximum number of half-wave patterns exist across the "a" dimension of a waveguide?

  1. One
  2. Two
  3. Three
  4. Four

3-45. With the mode description, TE1,0 what maximum number of half-wave patterns exist across the diameter of a circular waveguide?

  1. One
  2. Two
  3. Three
  4. Four

3-46. Which of the following devices CANNOT be used to inject or remove energy from a waveguide?

  1. A slot
  2. A loop
  3. A probe
  4. A horn

3-47. Loose coupling is a method used to reduce the amount of energy being transferred from a waveguide. How is loose coupling achieved when using a probe?

  1. By doubling the size of the probe
  2. By increasing the length of the probe
  3. By decreasing the length of the probe
  4. By placing the probe directly in the center of the energy field

3-48. Increasing the size of the loop wire increases which of the following loop capabilities?

  1. Efficiency
  2. Bandwidth coverage
  3. Power-handling capability
  4. Each of the above

3-49. A waveguide that is not perfectly impedance matched to its load is not efficient. Which of the following conditions in a waveguide causes this inefficiency?

  1. Sine waves
  2. Dominant waves
  3. Standing waves
  4. Transverse waves

A waveguide iris that covers part of both the electric and magnetic planes acts as what type of equivalent circuit at the resonant frequency?

  1. As an inductive reactance
  2. As a shunt resistance
  3. As a capacitive reactance
  4. As a shorted 1/4 wave stub

3-51. A horn can be used as a waveguide termination device because it provides which of the following electrical functions?

  1. A reflective load
  2. An absorptive load
  3. An abrupt change in impedance
  4. A gradual change in impedance

​3-52. For a waveguide to be terminated with a resistive load, that load must be matched to which of the following properties of the waveguide?

  1. The bandwidth
  2. The frequency
  3. The inductance
  4. The characteristic impedance

3-53. A resistive device with the sole purpose of absorbing all the energy in a waveguide without causing reflections is a/an

  1. iris
  2. horn
  3. antenna
  4. dummy load

3-54. A resistive load most often dissipates energy in which of the following forms?

  1. Heat
  2. Light
  3. Magnetic
  4. Electrical

3-55. Reflections will be caused by an abrupt change in which of the following waveguide's physical characteristics?

  1. Size and shape only
  2. Size and dielectric material only
  3. Dielectric material and shape only
  4. Size, shape, and dielectric material

3-56. A waveguide bend that in the E and H plane must be greater than. two wavelengths to prevent

  1. cracking
  2. reflections
  3. energy gaps
  4. electrolysis

3-57. A flexible waveguide is used in short sections because of the power-loss disadvantages. What is the cause of this power loss?

  1. Walls are not smooth
  2. E and H fields are not perpendicular
  3. Cannot be terminated in its characteristic impedance
  4. Wall size cannot be kept consistent

3-58. The choke joint is used for what purpose in a waveguide?

  1. To reduce standing waves
  2. To restrict the volume of electron flow
  3. To prevent the field from rotating
  4. To provide a joint that can be disassembled during maintenance

3-59. A circular waveguide is normally used in a rotating joint because rotating a rectangular waveguide would cause which of the following unwanted conditions?

  1. Oscillation
  2. Large power
  3. Decrease in bandwidth
  4. Field—pattern distortion

3-60. In your waveguide inspection, you should be alert for which of the following problems?

  1. Corrosion
  2. Damaged surfaces
  3. Improperly sealed joints
  4. Each of the above

3-61. What type of corrosion occurs when dissimilar metals are in contact with each other?

  1. Contact
  2. Metallic
  3. Electrical
  4. Electrolytic

​3-62. Internal arcing in a waveguide is usually a symptom of which of the following conditions?

  1. Change in mode
  2. Electrolysis at a joint
  3. Moisture in the waveguide
  4. Gradual change in frequency

3-63. What is the primary purpose of a directional coupler?

  1. To sample the energy in a waveguide
  2. To change the phase of the energy in the waveguide
  3. To change the direction of energy travel in the waveguide
  4. To allow energy in the waveguide to travel in one direction only

3-64. What is the electrical distance between. the two holes in a simple directional coupler?

  1. 1/8 wavelength
  2. 1/4 wavelength
  3. 1/2 wavelength
  4. 3/4 wavelength

3-65. Of the following characteristics, which is NOT required for a device to be considered a resonant cavity?

  1. Be enclosed by conducting walls
  2. Possess resonant properties
  3. Contain oscillating electromagnetic fields
  4. Be round or elliptical in shape

3-66. What property gives a resonant cavity a narrow bandpass and allows very accurate tuning?

  1. Low Q
  2. High Q
  3. Inductive reactance
  4. Capacitive reactance

3-67. What factor(s) determine(s) the primary frequency of a resonant cavity?

  1. Size only
  2. Shape only
  3. Size and shape
  4. Q of the cavity

3-68. Tuning is the process of changing what property of a resonant cavity?

  1. The Q
  2. The power
  3. The cutoff frequency
  4. The resonant frequency


3-69. What are the two basic types of waveguide T junctions?

  1. H and T
  2. H and E
  3. Hybrid Ring and magic T
  4. Q and magic T

3-70. A waveguide junction in which the arm area extends from the main waveguide in the same direction as the electric field is an example of what type junction?

  1. E-type T
  2. H-type T
  3. H-type T junction
  4. H-type junction

3-71. Low power handling capabilities and internal power losses are the primary disadvantages of which of the following junctions?

  1. Magic T
  2. Rat race
  3. Duplexer
  4. Hybrid ring

3-72. The hybrid ring is usually used as what type of device in radar systems?

  1. Mixer
  2. Detector
  3. Duplexer
  4. Impedance matcher

This work is in the public domain in the United States because it is a work of the United States federal government (see 17 U.S.C. 105).

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