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. 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 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 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.

• 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

• 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 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 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.

• d. complex 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