Transmission Fundamentals
1. What is the opposition to the transfer of energy which is considered the dominant characteristic of a cable or circuit that emanates from its physical structure?
• a. Conductance
• b. Resistance
• c. Reactance
• d. Impedance
2. When load impedance equals to Zo of the line, it means that the load _____ all the power.
• a. reflects
• b. absorbs
• c. attenuates
• d. radiates
3. impedance matching ratio of a coax balun.
• a. 1:4
• b. 4:1
• c. 2:1
• d. 3:2
4. Which stands for dB relative level?
• a. dBrn
• b. dBa
• c. dBr
• d. dBx
5. Standard test tone used for audio measurement.
• a. 800 Hz • b. 300 Hz
• c. 100 Hz
• d. 1000 Hz
6. When VSWR is equal to zero, this means
• a. that no power is applied
• b. that the load is purely resistive
• c. that the load is a pure reactance
• d. that the load is opened
7. ______is the ratio of reflected voltage to the forward travelling voltage.
• a. SWR
• b. VSWR
• c. Reflection coefficient
• d. ISWR
8. Transmission line must be matched to the load to ______.
• a. transfer maximum voltage to the load
• b. transfer maximum power to the load
• c. reduce the load current
• d. transfer maximum current to the load
9. Which indicate the relative energy loss in a capacitor?
• a. Quality factor
• b. Reactive factor
• c. Dissipation factor
• d. Power factor
10. What is the standard test tone? • a. 0 dB
• b. 0 dBW
• c. 0 dBm
• d. 0 dBrn
11. The energy that neither radiated into space nor completely transmitted.
• a. Reflected waves
• b. Captured waves
• c. Incident waves
• d. Standing waves
12. Micron is equal to ______meter.
• a. 10-10
• b. 10-9
• c. 10-6
• d. 10-3
13. 1 Angstrom (A) is equal to ______.
• a. 10-3 micron
• b. 10-10 m
• c. 10-6 micron
• d. 10-6 m
14. Why is it impossible to use a waveguide at low radio frequencies?
• a. Because of the size of the waveguide
• b. Due to severe attenuation
• c. Due to too much radiation
• d. All of these 15. ______is the transmission and reception of information.
• a. Modulation
• b. Communications
• c. Radiation
• d. Emission
16. What is the loss of the circuit in dB if the power ration of output to input is 0.01?
• a. 20
• b. -20
• c. 40
• d. -40
17. Transmission lines are either balanced or unbalanced with respect to
• a. Negative terminal
• b. Reference
• c. Ground
• d. Positive terminal
18. The standing wave ratio is equal to ______if the load is properly matched with the transmission line.
• a. Infinity
• b. 0
• c. -1
• d. 1
19. ______is the advantage of the balanced transmission line compared to unbalanced line.
• a. Low attenuation
• b. Easy installation
• c. Low radiation loss • d. Tensile strength
20. ______is the method of determining the bandwidth of any processing system.
• a. Fourier series
• b. Spectral analysis
• c. Frequency analysis
• d. Bandwidth analysis
21. What causes the attenuation present in a waveguide?
• a. The air dielectric filling the guide
• b. The coating of silver inside
• c. Losses in the conducting walls of the guide
• d. Radiation loss
22. A device that converts a balanced line to an unbalanced line of a transmission line.
• a. Hybrid
• b. Stub
• c. Directional coupler
• d. Balun
23. What is the approximate line impedance of a parallel-strip line spaced 1 cm apart with the length of 50 cm?
• a. 10 ohms
• b. 15 ohms
• c. 18 ohms
• d. 23 ohms
24. What is the average power rating of RG-58 C/u?
• a. 25 W
• b. 50 W • c. 75 W
• d. 200 W
25. A coaxial cable used for high temperatures.
• a. RG-58C
• b. RG-11A
• c. RG-213
• d. RG-211
26. If you have available number of power amplifiers with a gain of 100 each, how many such amplifiers do you need to cascade to give an overall gain of 60dB?
• a. 2
• b. 3
• c. 4
• d. 5
27. You are measuring noise in a voice channel at a -4 dB test point level, the meter reads -73 dBm, convert the reading into dBrnCO.
• a. 12
• b. 16
• c. 18
• d. 21
28. The velocity factor for a transmission line
• a. depends on the dielectric constant of the material used
• b. increases the velocity along the transmission line
• c. is governed by the skin effect
• d. is higher for a solid dielectric than for air
29. Impedance inversion can be obtained by • a. a short-circuited stub
• b. an open-circuited stub
• c. a quarter-wave line
• d. a half-wave line
30. Transmission lines when connected to antennas have
• a. capacitive load
• b. resistive load whose resistance is greater than the characteristic impedance of the line
• c. resistive load whose resistance is less than the characteristic impedance of the line
• d. resistive load at the resonant frequency
31. One of the following is not a bounded media.
• a. Coaxial line
• b. Two-wire line
• c. Waveguide
• d. Ocean
32. The impedance measured at the input of the transmission line when its length is infinite.
• a. Input impedance
• b. Open circuit impedance
• c. Characteristic impedance
• d. Short circuit impedance
33. The following are considered primary line constants except
• a. conductance
• b. resistance
• c. capacitance
• d. complex propagation constant 34. The dielectric constants of materials commonly used in transmission lines range from about
• a. 1.2 to 2.8
• b. 2.8 to 3.5
• c. 3.5 to 5.2
• d. 1.0 to 1.2
35. Typically, the velocity factor (VF) of the materials used in transmission lines range from
• a. 0.6 to 0.9
• b. 0.1 to 0.5
• c. 1.0 to 0.9
• d. 0.6 to 0.8
36. For an air dielectric two-wire line, the minimum characteristic impedance value is
• a. 85 ohms
• b. 85 ohms
• c. 90 ohms
• d. 88 ohms
37. When a quarter-wave section transmission line is terminated by a short circuit and is connected to an RF source at the other end, its input impedance is
• a. inductive
• b. capacitive
• c. resistive
• d. equivalent to a parallel resonant LC circuit
38. A transmitter operating at 30 MHz with 4 W output is connected via 10 m of RG-8A/u cable to an antenna that has an input resistance of 300 ohms. Find the reflection coefficient.
• a. 0.71
• b. 0.77 • c. 0.97
• d. 0.76
39. A quarter wave transformer is connected to a parallel wire line in order to match the line to a load of 1000 ohms. The transformer has a characteristic impedance of 316.23 ohms. The distance between centers is 4 inches. What is the percentage reduction in the diameter of the line?
• a. 85%
• b. 83%
• c. 86%
• d. 90%
40. The concept used to make one Smith chart universal is called
• a. ionization
• b. normalization
• c. rationalization
• d. termination
41. What are the basic elements of communications system?
• a. Source, transmission channel, transmitter
• b. Transmitter, receiver, transmission channel
• c. Information, transmission channel, receiver
• d. Sender and receiver
42. ______is the transmission of printed material over telephone lines.
• a. Internet
• b. Data communication
• c. Telegraphy
• d. Facsimile
43. ______is a continuous tone generated by the combination of two frequencies of 350 Hz and 440 Hz used in telephone sets. • a. DC tone
• b. Ringing tone
• c. Dial tone
• d. Call waiting tone
44. ______are unidirectional amplifiers having 20-25 decibel gain that are placed about 75 km apart used to compensate for losses along the telephone line.
• a. VF repeaters
• b. Loading coils
• c. Loop extenders
• d. Echo suppressors
45. ______is a component in the telephone set that has the primary function of interfacing the handset to the local loop.
• a. Resistor
• b. Capacitor
• c. Varistor
• d. Induction coil
46. Pulse dialing has ______rate.
• a. 20 pulses/min
• b. 10 pulses/min
• c. 10 pulses/sec
• d. 80 pulses/sec
47. ______is a telephone wire that connects two central offices.
• a. 2-wire circuit
• b. Trunk line
• c. Leased line