CHAPTER 7: TRANSMISSION LINES

1. Indicate the false statement. The SWR on a transmission line infinity; the line is terminated ina. a short circuitb. a complex impedancec. an open circuitd. a pure resistance

2. A (75 - j50) load is connected to a coaxial transmission line of Zo = 75, at 10GHz. The best method of matching consists in connectinga. a short circuited stub at the loadb. an inductance at the loadc. a capacitance at some specific distance from the loadd. a short circuited stub at some specific distance from the load

3. The velocity factor of a transmission linea. depends on the dielectric constant of the material usedb. increase the velocity along the transmission linec. is governed by the skin effectd. is higher for a solid dielectric than for air

4. Impedance inversion may be obtained witha. a short circuited stubb. an open circuited stubc. a quarter wave lined. a half wave line

5. Short-circuited stubs are preferred to open circuited stub because the latter area. more difficult to make and connectb. made of transmission line with a different characteristic impedancec. liable to radiated. incapable of giving a full range of reactance

6. For a transmission line load matching over a range of frequencies, it is best to use aa. balun b. broadband directional couplerc. double stubd. single stud of adjustable position

7. The main disadvantage of the two hole directional couple isa. low directional couplingb. poor directivityc. high SWRd. narrow bandwidth

8. To couple a coaxial line to a parallel wire, it is best to use aa. slotted lineb. balun c. directional couplerd. quarter wave transformer

9. Indicate the three types of transmission line energy lossesa. (I^2)R, RL, and temperatureb. Radiation, (I^2)R, and dielectric heatingc. Dielectric separation, insulation breakdown, and radiationd. Conductor heating, dielectric heating, and radiation resistance

10. Indicate the true statement below. The directional coupler isa. A device used to connect a transmitter to a directional antennab. A coupling device for matching impedancec. A device used to measure transmission line powerd. An SWR measuring instrument

CHAPTER 8: RADIATION AND PROPAGATION OF WAVES

1. Indicated which one of the following terms applies to troposcatter propagation:a. SIDsb. Fadingc. Atmospheric stormsd. Faraday Rotation

2. VLF waves are used for some types of services becausea. of the low powers requiredb. the transmitting antennas are of convenient sizec. they are very reliabled. they penetrate the ionosphere easily

3. Indicate which of the following frequencies cannot be used for reliable beyond the horizon terrestrial communication without repeatersa. 20KHzb. 15MHzc. 900MHzd. 12GHz

4. High frequency waves area. absorbed by the F2 layerb. reflected by the D layerc. capable of use for long distance communication on the moond. affected by the solar cycle

5. Distances near the skip distance should be used for the sky-wave propagationa. to avoid tiltingb. to prevent sky-wave and upper ray interferencec. to avoid the Faraday effectd. so as not to exceed the critical frequency

6. A ship-to-ship communication system is plagued by fading. The best solution seems to be the use of

a. a more directional antennasb. broadband antennasc. frequency diversityd. space diversity

7. A range of microwave frequency more easily passed by the atmosphere than the other is called aa. windowb. critical frequencyc. gyro frequency ranged. Resonance in the atmosphere

8. Frequencies in the UHF range normally propagate by means ofa. ground wavesb. sky wavesc. surface wavesd. space waves

9. Tropospheric scatter is used with frequencies in the following rangea. HFb. VHFc. UHFd. VLF

10. The ground wave eventually disappears, as one moves away from the transmitter, because ofa. interference from the sky waveb. loss of line of sight conditionsc. maximum single hop distance limitationsd. tilting

11. In electromagnetic waves, polarizationa. is caused by reflectionb. is due to the transverse nature of the wavesc. results from the longitudinal nature of wavesd. is always vertical in an isotropic antenna

12. As electromagnetic waves travel in free space, one the following can happen to them:a. absorptionb. attenuationc. refractiond. reflection

13. The absorption of radio waves by the atmosphere depends ona. their frequencyb. their distance from the transmitterc. the polarization of the wavesd. the polarization of the atmosphere

14. Electromagnetic waves are refracted when theya. pass into a medium of different dielectric constant

b. are polarized at right angles to the direction of propagationc. encounter a perfectly conducting surfaced. pass through small slot in a conducting plane

15. Diffraction of electromagnetic wavea. is caused by reflections from the groundb. arises only with the spherical wave frontsc. will occur when the waves pass through a large slotd. may occur around the edge of a sharp obstacle

16. When microwave signals follow the curvature of the earth, this is known asa. the Faraday effectb. ductingc. troposheric scatterd. ionospheric reflections

17. Helical antennas are often used for satellite tracking at VHF because ofa. troposcatter b. superrefraction c. ionospheric refractiond. the Faraday effect

CHAPTER 9: ANTENNAS

1. An ungrounded antenna near the grounda. acts a single antenna of twice the heightb. is unlikely need an earth matc. acts as an antenna arrayd. must be horizontally polarized

2. One of the following consist of non resonant antennaa. rhombic antennab. folded dipolec. end fire arrayd. broadside array

3. One of the following is very useful as a multiband HF receiving antenna. This is thea. conical hornb. folded dipolec. log-periodicd. square loop

4. Which of the following antenna is best excited from a waveguide?a. biconical b. hornc. helicald. discone

5. Indicate which of the following reasons for using a counter poise with antenna is falsea. impossibility of a good ground connection

b. protection of personnel working undergroundc. provision of an earth for the antennad. rockiness of the ground itself

6. One of the following is not a reason for the use of an antenna coupler:a. to make the antenna look resistiveb. to provide the output amplifier with the correct load impedancec. to discriminate against harmonicsd. to prevent re-radiation of the local oscillator

7. Indicate the antenna that is not wideband:a. Discone b. Folded dipolec. Helicald. Marconi

8. Indicate which of the following reasons for use of an earth mat with antennas is false:a. impossibility of a good ground connectionb. provision of an earth for the antennac. protection of personnel working underneathd. improvement of radiation pattern of the antenna

9. Which one of the following terms does not apply the yagi-uda array?a. good bandwidthb. parasitic elementsc. folded dipoled. high gain

10. An antenna that is circularly polarized is thea. helicalb. small circular loopc. parabolic reflectord. yagi–uda

11. The standard reference antenna for the directive gain is thea. infinitesimal dipoleb. isotropic antennac. elementary doubletd. half wave dipole

12. Top loading is sometimes used with an antenna in order to increase itsa. effective heightb. bandwidthc. beam widthd. input capacitance

13. Cassegrain feed is used with a parabolic reflector toa. increase the gain of the systemb. increase the beam width of the systemc. reduce the size of the main reflectord. allow the feed to be placed at a convenient point

14. Zoning is used with a dielectric antenna in order toa. reduce the bulk of the lensb. increase the bandwidth of the lensc. permit pin point focusingd. correct the curvature of the wave front from a horn that is too short

15. Helical antenna is used for satellite tracking because of itsa. circular polarizationb. maneuverabilityc. broad bandwidthd. good front to back ratio

16. The discone antenna isa. a useful direction finding antennab. used as a radar receiving antennac. circularly polarized like other circular antennasd. useful as a UHF receiving antenna

17. One of the following is not an omni directional antennaa. Half wave dipoleb. Log periodicc. Discone d. Marconi

CHAPTER 10: WAVEGUIDES, RESONATORS AND

COMPONENTS

1. When electromagnetic waves are propagated in a wave guidea. they travel along the broader walls of the guideb. they are reflected from the walls but do not travel along themc. they travel through the dielectric without touching the wallsd. they travel along all four walls of the waveguide

2. Waveguides are used mainly for microwave signals becausea. the depend on the straight line propagation which applies to microwaves onlyb. losses would be to heavy at lower frequenciesc. there are no generators powerful enough to excite them at lower frequenciesd. they would be too bulky at lower frequencies

3. The wavelength of a wave in a waveguidea. is greater than in free spaceb. depends only on the wave guide dimensions and the free space wavelengthc. is inversely proportional to the phase velocityd. is directly proportional to the group velocity

4. The main difference between the operation of transmission lines and wave guides is thata. the latter are not distributed, like transmission linesb. the former can use stubs and quarter wave transformers, unlike the latterc. transmission lines use the principal mode of propagation, and therefore do not suffer from low frequency cut offd. terms such as impedance matching and standing wave ration cannot be applied to waveguides

5. Compared with the equivalent transmission line, 3GHz waveguides (indicate the false statement)a. are less lossy b. can carry high powersc. are less bulkyd. have lower attenuation

6. When a particular mode is excited in a waveguide, there appears an extra electric component, in the direction of propagation. The resulting mode isa. transverse-electricb. transverse-magneticc. longitudinald. transverse-electromagnetic7. When electromagnetic waves are reflected at an angle from a wall, their wave length along the wall isa. the same as in free spaceb. the same as the wavelength perpendicular to the wallc. shortened because of the Doppler effectd. greater than in the actual direction of propagation

8. As a result of reflections from a plane conducting wall, electromagnetic waves require an apparent velocity greater than the velocity of light in space. This is calleda. velocity of propagationb. normal velocityc. group velocityd. phase velocity

9. Indicate the false statement. When the free space wavelength of a signal equals the cutoff waveguide of the guidea. the group velocity of the signal becomes zerob. the phase velocity of the signal becomes infinitec. the characteristic impedance of the guide becomes infinited. the wavelength within the wave guide becomes infinite

10. A signal propagated in a waveguide has a full wave of electric intensity change between the two further walls, and no component of the electric field in the direction of propagation. The mode isa. TE 1,1

b. TE 1,0c. TM 2,2d. TE 2,0

11. The dominant mode of propagation is preferred with rectangular waveguides because (false)a. it leads to the smallest waveguide dimensionsb. the resulting impedance can be matched directly to coaxial linesc. it is easier to excite than the other modesd. propagation of it without any spurious generation can be ensured

12. A choke flange may be used to couple two waveguidesa. to help in alignment of the waveguidesb. because it is simpler than any other joinc. to compensate for discontinuities at the joind. to increase the bandwidth of the system

13. In order to couple two generators to a waveguide system without coupling them to each other, one could not use aa. rat raceb. E – plane Tc. Hybrid ringd. Magic T

14. Which of the following waveguide tuning components is not easily adjustable?a. screwb. stubc. irisd. plunger

15. A piston attenuator is aa. vane attenuatorb. waveguide below cutoffc. mode filterd. flap attenuator

16. Cylindrical cavity resonators are not used with klystrons because they havea. a Q that is too lowb. a shape whose resonant frequency is too difficult to calculatec. harmonically related resonant frequenciesd. too heavy losses

17. A directional coupler with three or more holes is sometimes used in preference to the two hole couplera. because it is more efficientb. to increase coupling of the signalc. to reduce spurious mode generationd. to increase the bandwidth of the system

18. A ferrite isa. a non conductor with magnetic propertiesb. an intermetallic compound with particularly good conductivityc. an insulator which heavily attenuates magnetic fieldsd. a microwave semiconductor invented by faraday

19. Manganese ferrite may be used as a (false)a. circulatorb. isolatorc. garnetd. phase shifter

20. The maximum power that may be handled by a ferrite component is limited by thea. curie temperatureb. saturation magnetizationc. line widthd. gyromagnetic resonance

21. A PIN diode isa. a metal semiconductor point contact diodeb. a microwave mixer diodec. often used as a microwave detectord. suitable for the use as a microwave switch

22. A duplexer is useda. to couple two different antennas to a transmitter without mutual interferenceb. to allow the one antenna to be used for reception or transmission without mutual interferencec. To prevent interference between two antennas when they are connected to a receiverd. to increase the speed of the pulses in pulsed radar

23. For some applications, circular waveguides may be preferred to rectangular ones because ofa. smaller cross section needed at any frequencyb. lower attenuationc. freedom from spurious modesd. rotation of polarization

24. Indicate which of the following cannot be followed by the word “waveguide”:a. Ellipticalb. Flexiblec. Coaxiald. Ridged

25. In order to reduce cross sectional dimensions, the waveguide to use isa. circular

b. ridgedc. rectangulard. flexible

26. For low attenuation, the best transmission medium isa. flexible waveguideb. ridged waveguidec. rectangular waveguided. coaxial line

CHAPTER 18: INTRODUCTION TO FIBER OPTIC TECHNOLOGY

1. What is the frequency limit of copper wire?a. Approximately 0.5 MHzb. Approximately 1.0 MHzc. Approximately 40 GHzd. None of the above

2. Approximately what is the frequency limit of the optical fiber?a. 20 GHz (no given answer)b. 1 MHzc. 100 MHzd. 40 MHz

3. A single fiber can handle as many voice channels asa. A pair of copper conductorsb. A 1500-pair cablec. A 500-pair cabled. A 1000- pair cable

4. An incident ray can be defined asa. A light ray reflected from a flat surfaceb. A light ray directed towards a surfacec. A diffused light rayd. A light ray that happens periodically

5. The term dispersion describes the process ofa. Separating light into its component frequenciesb. Reflecting light from a smooth surfacec. The process by which light is absorbed by an uneven rough surfaced. Light scattering

6. The cladding which surrounds the fiber corea. Is used to reduce optical interferenceb. Is used to protect the fiberc. Acts to help guide the light in the cored. Ensures that the refractive index remains constant

7. Which of the following terms describes the reason that light is refracted at different angles?a. Photon energy changes with wavelengthb. Light is refracted as a function of surface smoothness

c. The angle is determined partly by a and bd. The angle is determined by the index of the materials

8. The term critical angle describesa. The point at which light is refractedb. The point at which light becomes invisiblec. The point at which light has gone from the refractive mode to the reflective moded. The point at which light has crossed the boundary layers from one index to another

9. The reflective index number isa. A number which compares the transparency of a material with that of airb. A number assigned by the manufacturer to the fiber in questionc. A number which determines the core diameterd. A term for describing core elasticity

10. The terms single mode and multimode are best described asa. The number of fibers placed into a fiber-optic cableb. The number of voice channels each fiber can supportc. The number of wavelengths each fiber can supportd. The index number

11. The higher the index numbera. The higher the speed of lightb. The lower the speed of lightc. Has no effect on the speed of lightd. The shorter the wavelength propagation

12. The three major groups in the optical system area. The components, the data rate, and the response timeb. The source, the link, and the receiverc. The transmitter, the cable, and the receiverd. The source, the link, and the detector

13. As light is coupled in a multipoint reflective device, the power is reduce bya. 1.5 dBb. 0.1 dBc. 0.5 dBd. 0.001 dB

14. When connector losses, splice losses, and coupler losses are added, what is the final limiting factor?a. Source powerb. Fiber attenuationc. Connector and splice lossesd. Detector sensitivity

15. The term responsivity as it applies to a light detector is best described asa. The time required for the signal to go from 10 to 90 percent of maximum amplitudeb. The ratio of the diode output current to optical input powerc. The ratio of output current to output powerd. The ratio of output current to input current

16. Loss comparisons between fusion splices and mechanical splices area. 1:10b. 10:1c. 20:1d. 1:20

17. The mechanical splice is best suited fora. Quicker installation under ideal conditionsb. Minimum attenuation lossesc. Field service conditionsd. Situations in which cost of equipment is not a factor

18. EMD is best described by which statement?a. 70 percent of the core diameter and 70 percent of the fiber NA should be filled with lightb. 70 percent of the fiber diameter and 70 percent of the cone of acceptance should be filled with lightc. 70 percent of input light should be measured at the outputd. 70 percent of the unwanted wavelengths should be attenuated by the fiber

19. Which of the following cables will have the highest launch power capabilitya. 50/125/0.2b. 85/125/0.275c. 62.5/125/0.275d. 100/140/0.3

20. The term power budgeting refers toa. The cost of cables, connectors, equipment, and installationb. The loss of power due to defective componentsc. The total power available minus the attenuation lossesd. The comparative costs of fiber and copper installations