FCC Technician Exam Question Pool. Subelement 3AC. Radio Wave Propagation. 3 Questions. -------------------------------------------------- 3C 1.1 A What is the IONOSPHERE? A. That part of the upper atmosphere where enough ions and free electrons exist to affect radio wave propagation. B. The boundary between two air masses of different temperature and humidity, along which radio waves can travel. C. The ball that goes on the top of a mobile whip antenna. D. That part of the atmosphere where weather takes place. 3C 1.2 A Which Ionospheric layer limits daytime radiocommunications in the 80 meter band to short distances? A. D layer. B. F1 layer. C. E layer. D. F2 layer. 3C 1.3 D What is the region of the outer atmosphere which makes long distance radiocommunications possible as a result of bending of radio waves? A. Troposphere. B. Stratosphere. C. Magnetosphere. D. Ionosphere. 3C 1.4 D Which layer of the Ionosphere is mainly responsible for long distance sky wave radiocommunication? A. D layer. B. E layer. C. F1 layer. D. F2 layer. 3C 1.5 B What are the two distinct sublayers of the F layer during the daytime? A. Troposphere and Stratosphere. B. F1 and F2. C. Electrostatic and Electromagnetic. D. D and E. 3C 1.8 B What is the lowest region of the Ionosphere that is useful for long distance radio wave propagation? A. The D layer. B. The E layer. C. The F1 layer. D. The F2 layer. 3C 1.11 C What type of solar radiation is most responsible for ionization in the outer atmosphere? A. Thermal. B. Ionized particle. C. Ultraviolet. D. Microwave. 3C 1.12 B What is the lowest Ionospheric layer? A. The A layer. B. The D layer. C. The E layer. D. The F layer. 3C 1.14 A What is the region of the outer atmosphere which makes Long Distance radiocommunications possible as a result of bending of the radio waves? A. The Ionosphere. B. The Troposphere. C. The Magnetosphere. D. The Stratosphere. 3C 2.1 D Which layer of the Ionosphere is most responsible for absorption of radio signals during daylight hours? A. The E layer. B. The F1 layer. E. The F2 layer. D. The D layer. 3C 2.2 A When is Ionospheric absorption most pronounced? A. When radio waves enter the D Layer at low angles. B. When Tropospheric ducting occurs. C. When radio waves travel to the F Layer. D. When a temperature inversion occurs. 3C 2.5 A During daylight hours, what effect does the D Layer of the Ionosphere have on 80 meter radio waves? A. The D Layer absorbs the signals. B. The D Layer bends the radio waves out into space. C. The D Layer refracts the radio waves back to Earth. D. The D Layer has little or no effect on 80 meter radio wave propagation. 3C 2.6 B What causes IONOSPHERIC ABSORPTION of radio wave? A. A lack of D Layer ionization. B. D Layer ionization. C. The presence of ionized clouds in the E Layer. D. Splitting of the F Layer. 3C 3.1 D What is the highest radio frequency that will be refracted back to Earth called? A. Lowest Usable Frequency. B. Optimum Working Frequency. C. Ultra High Frequency. D. Critical Frequency. 3C 3.2 D What causes the MAXIMUM USABLE FREQUENCY to vary? A. Variations in the temperature of the air at Ionospheric levels. B. Upper atmospheric wind patterns. C. Intensity of auroral activity. D. The amount of ultraviolet and other types of radiation received from the Sun. 3C 3.5 A What does the term MAXIMUM USABLE FREQUENCY refer to? A. The maximum frequency that allows a radio signal to reach its destination in a single hop. B. The minimum frequency that allows a radio signal to reach its destination in a single hop. C. The maximum frequency that allows a radio signal to be absorbed in the lowest Ionospheric layer. D. The minimum frequency that allows a radio signal to be absorbed in the lowest Ionospheric layer. 3C 4.1 D What is usually the condition of the Ionosphere just before sunrise? A. Atmospheric attenuation is at a maximum. B. Ionization is at a maximum. C. The E layer is above the F layer. D. Ionization is at a minimum. 3C 4.2 D At what time of day does maximum ionization of the Ionosphere occur? A. Dusk. B. Midnight. C. Dawn. D. Midday. 3C 4.3 D Which two daytime Ionospheric layers combine into one layer at night? A. E and F1. B. D and E. C. E1 and E2. D. F1 and F2. 3C 4.4 A Minimum ionization of the Ionosphere occurs daily at what time? A. Shortly before Dawn. B. Just after Midday. C. Just after Dusk. D. Shortly before Midnight. 3C 6.1 C When two stations are within each other's skip zone on the frequency being used, what mode of propagation would it be desirable to use? A. Ground Wave propagation. B. Sky Wave propagation. C. Scatter Mode propagation. D. Ionospheric Ducting propagation. 3C 6.3 B When is E Layer ionization at a maximum? A. Dawn. B. Midday. C. Dusk. D. Midnight. 3C 8.1 A What is the transmission path of a wave that travel directly from the transmitting antenna to the receiving antenna called? A. Line of sight. B. The sky wave. C. The linear wave. D. The plane wave. 3C 8.2 B How are VHF signals within the range of the visible horizon propagated? A. By sky wave. B. By direct wave. C. By plane wave. D. By geometric wave. 3C 9.1 D Ducting occurs in which region of the atmosphere? A. F2. B. Ionosphere. C. Stratosphere. D. Troposphere. 3C 9.2 A What effect does tropospheric bending have on 2 meter radio waves? A. It increases the distance over which they can be transmitted. B. It decreases the distance over which they can be transmitted. C. It tends to garble 2 meter phone transmissions. D. It reverses the sideband of 2 meter phone transmissions. 3C 9.3 D What atmospheric phenomenon causes tropospheric ducting of radio waves? A. A very low pressure area. B. An Aurora to the North. C. Lightning between the transmitting and receiving station. D. A temperature inversion. 3C 9.4 A Tropospheric ducting occurs as a result of what phenomenon? A. A temperature inversion. B. Sun spots. C. An Aurora to the North. D. Lightning between the transmitting and receiving station. 3C 9.5 B What atmospheric phenomenon causes VHF radio waves to be propagated several hundred miles through stable air masses over oceans? A. Presence of a maritime polar air mass. B. A widespread temperature inversion. C. An overcast of cirriform clouds. D. Atmospheric pressure of roughly 29 inches of Mercury or higher. 3C 9.6 D In what frequency range does tropospheric ducting occur most often? A. LF. B. MF. C. HF. D. VHF. -------------------------------------------------- End of Subelement 3AC.