35. (213) Direct waves are radio waves that travel

a. long distances with few interruptions.

b. from point to point along the earth’s surface.

c. through the air in a straight line.

d. no more than 20 miles to the receive antenna.

36. (213) Radio waves that travel near the earth’s surface are called

a. earth waves.

b. global waves.

c. ground waves.

d. terrestrial waves.

37. (213) Sky wave transmission is used for which type of communications?

a. Long distance.

b. Subterrestrial.

c. Atmospheric.

 d. Line of sight.

38. (214) The path that undergoes a 180° phase shift is a

a. ground-reflected path.

b. surface path.

c. direct path.

d. sky path.

39. (214) Which gives sky wave propagation its ability to communicate beyond the optical line-of-sight (LOS)?

a. Refraction.

b. Reflection.

c. Earth’s conductivity.

d. Atmospheric charge.

40. (214) Frequencies higher than the critical frequency are

a. returned to earth.

b. passed into space.

c. the most desirable.

d. refracted by the F2 layer.

41. (214) In high frequency (HF) communications, the lowest frequency that arrives at the distant receiver on 90 percent of the undisturbed days of the month is called the

a. maximum usable frequency ( MUF).

b. lowest usable frequency (LUF).

c. operating frequency.

d. critical frequency.

42. (214) The abbreviation FOT is derived from the term

a. outbound traffic frequency.

b. optimum tropospheric frequency.

c. frequency of optimum transmission.

d. frequency of outbound transmission.

43. (214) Magneton splitting creates two waves called

a. direct and indirect.

b. ordinary and abnormal.

c. in-phase and out-of-phase.

d. ordinary and extraordinary.

44. (214) What occurs when a transmitted signal travels over two or more separate paths during transmission?

a. Skip effects.

b. Modulation.

c. Multipathing.

d. Magneton splitting.

45. (215) What is the recombination process dependent upon?

a. Season.

b. Time of day.

c. Regular variation.

d. Irregular variations.

46. (215) Which layer of the ionosphere is most important to high frequency (HF) communications?

a. D.

b. E.

c. F.

d. Topside.

47. (215) During what season do we have the wider range of critical frequencies and less absorption of all frequencies?

a. Fall.

b. Winter.

c. Spring.

d. Summer.

48. (215) Sunspots are disturbances

a. in the sun’s atmosphere.

b. on the sun’s surface.

c. in the ionosphere.

d. beneath the sun’s surface.

49. (216) For communications purposes, the usable frequency spectrum ranges from

a. 3 hertz (Hz) to 300 gigahertz (GHz+.

b. 300 Hz to 300 GHz.

c. 3000Hz to 3000 GHz.

d. 30 megahertz (MHz) to 300 MHz.

50. (216) What U.S. government agency divides the radio frequency (RF) spectrum into different bands?

a. Federal Aviation Agency.

b. American National Standard Institute.

 c. Federal Communications Commission.

d. Institute of Electrical & Electronics Engineers, Inc.

51. (217) Near-vertical-incidence sky (NVIS) wave operations are most effective when you’re using

a. lower high frequency (HF) frequencies.

b. higher HF frequencies.

c. medium HF frequencies.

d. low takeoff antenna angles.

52. (217) What frequency band is most susceptible to jamming?

a. Low frequency.

b. Medium frequency.

c. High frequency.

d. Very high frequency.

53. (217) What frequency bands does the MILSTAR satellite system use?

a. High frequency (HF) and ultrahigh frequency (UHF).

b. Super-high frequency (SHF) and extremely high frequency (EHF).

c. Very high frequency (VHF) and SHF.

d. VHF and UHF.

54. (218) The main very high frequency (VHF)/ultra high frequency (UHF) communications emphasis is on

a. long range deployable communications.

b. short range fixed communications.

c. emergency communications.

d. air-ground communications.

55. (219) Super high frequency (SHF)/extremely high frequency (EHF) range is limited to

a. scattering.

b. line-of-sight (LOS).

c. Earth’s conductivity.

d. atmospheric absorption.

56. (220) In a move to overcome the limited range of forward propagation by tropospheric scatter (FPTS) without requiring many costly relay systems, what was developed?

a. Optical horizon radar.

b. Satellite communications.

c. Microwave communications.

d. Line-of-sight (LOS) communications.

57. (220) Why isn’t very high frequency (VHF) normally used for satellite communications?

a. The frequency is too low.

b. The frequency is too high.

c. Ionospheric refraction can occur.

d. The rate of absorption is too great.

58. (220) When comparing the radio and optical horizons, which one is farther away and by what percent?

a. Optical; 15.

b. Radio; 15.

c. Optical; 33.

d. Radio; 33.

59. (220) When K is greater than 4/3, the radio horizon will

a. decrease, then increase.

b. remain the same.

c. decrease.

d. increase.