G3 - RADIO WAVE PROPAGATION [3 Exam Questions - 3 Groups]

Question 1

What is the sunspot number?

A. A measure of solar activity based on counting sunspots and sunspot groups

B. A 3 digit identifier which is used to track individual sunspots

C. A measure of the radio flux from the Sun measured at 10.7 cm

D. A measure of the sunspot count based on radio flux measurements

Answer 1

A. A measure of solar activity based on counting sunspots and sunspot groups

Question 2

What effect does a Sudden Ionospheric Disturbance have on the daytime ionospheric propagation of HF radio waves?

A. It enhances propagation on all HF frequencies

B. It disrupts signals on lower frequencies more than those on higher frequencies

C. It disrupts communications via satellite more than direct communications

D. None, because only areas on the night side of the Earth are affected

Answer 2

B. It disrupts signals on lower frequencies more than those on higher frequencies

Question 3

Approximately how long does it take the increased ultraviolet and X-ray radiation from solar flares to affect radio-wave propagation on the Earth?

A. 28 days

B. 1 to 2 hours

C. 8 minutes

D. 20 to 40 hours

Answer 3

C. 8 minutes

Question 4

Which of the following amateur radio HF frequencies are least reliable for long distance communications during periods of low solar activity?

A. 3.5 MHz and lower

B. 7 MHz

C. 10 MHz

D. 21 MHz and higher

Answer 4

D. 21 MHz and higher

Question 5

What is the solar-flux index?

A. A measure of the highest frequency that is useful for ionospheric propagation between two points on the Earth

B. A count of sunspots which is adjusted for solar emissions

C. Another name for the American sunspot number

D. A measure of solar radiation at 10.7 cm

Answer 5

D. A measure of solar radiation at 10.7 cm

Question 6

What is a geomagnetic storm?

A. A sudden drop in the solar-flux index

B. A thunderstorm which affects radio propagation

C. Ripples in the ionosphere

D. A temporary disturbance in the Earth’s magnetosphere

Answer 6

D. A temporary disturbance in the Earth’s magnetosphere

Question 7

At what point in the solar cycle does the 20 meter band usually support worldwide propagation during daylight hours?

A. At the summer solstice

B. Only at the maximum point of the solar cycle

C. Only at the minimum point of the solar cycle

D. At any point in the solar cycle

Answer 7

D. At any point in the solar cycle

Question 8

Which of the following effects can a geomagnetic storm have on radio-wave propagation?

A. Improved high-latitude HF propagation

B. Degraded high-latitude HF propagation

C. Improved ground-wave propagation

D. Improved chances of UHF ducting

Answer 8

B. Degraded high-latitude HF propagation

Question 9

What effect do high sunspot numbers have on radio communications?

A. High-frequency radio signals become weak and distorted

B. Frequencies above 300 MHz become usable for long-distance communication

C. Long-distance communication in the upper HF and lower VHF range is enhanced

D. Microwave communications become unstable

Answer 9

C. Long-distance communication in the upper HF and lower VHF range is enhanced

Question 10

What causes HF propagation conditions to vary periodically in a 28-day cycle?

A. Long term oscillations in the upper atmosphere

B. Cyclic variation in the Earth’s radiation belts

C. The Sun’s rotation on its axis

D. The position of the Moon in its orbit

Answer 10

C. The Sun’s rotation on its axis

Question 11

Approximately how long is the typical sunspot cycle?

A. 8 minutes

B. 40 hours

C. 28 days

D. 11 years

Answer 11

D. 11 years

Question 12

What does the K-index indicate?

A. The relative position of sunspots on the surface of the Sun

B. The short term stability of the Earth�s magnetic field

C. The stability of the Sun’s magnetic field

D. The solar radio flux at Boulder, Colorado

Answer 12

B. The short term stability of the Earth�s magnetic field

Question 13

What does the A-index indicate?

A. The relative position of sunspots on the surface of the Sun

B. The amount of polarization of the Sun’s electric field

C. The long term stability of the Earth�s geomagnetic field

D. The solar radio flux at Boulder, Colorado

Answer 13

C. The long term stability of the Earth�s geomagnetic field

Question 14

How are radio communications usually affected by the charged particles that reach the Earth from solar coronal holes?

A. HF communications are improved

B. HF communications are disturbed

C. VHF/UHF ducting is improved

D. VHF/UHF ducting is disturbed

Answer 14

B. HF communications are disturbed

Question 15

How long does it take charged particles from coronal mass ejections to affect radio-wave propagation on the Earth?

A. 28 days

B. 14 days

C. 4 to 8 minutes

D. 20 to 40 hours

Answer 15

D. 20 to 40 hours

Question 16

What is a possible benefit to radio communications resulting from periods of high geomagnetic activity?

A. Aurora that can reflect VHF signals

B. Higher signal strength for HF signals passing through the polar regions

C. Improved HF long path propagation

D. Reduced long delayed echoes

Answer 16

A. Aurora that can reflect VHF signals

Question 17

How might a sky-wave signal sound if it arrives at your receiver by both short path and long path propagation?

A. Periodic fading approximately every 10 seconds

B. Signal strength increased by 3 dB

C. The signal might be cancelled causing severe attenuation

D. A well-defined echo might be heard

Answer 17

D. A well-defined echo might be heard

Question 18

Which of the following is a good indicator of the possibility of sky-wave propagation on the 6 meter band?

A. Short skip sky-wave propagation on the 10 meter band

B. Long skip sky-wave propagation on the 10 meter band

C. Severe attenuation of signals on the 10 meter band

D. Long delayed echoes on the 10 meter band

Answer 18

A. Short skip sky-wave propagation on the 10 meter band

Question 19

Which of the following applies when selecting a frequency for lowest attenuation when transmitting on HF?

A. Select a frequency just below the MUF

B. Select a frequency just above the LUF

C. Select a frequency just below the critical frequency

D. Select a frequency just above the critical frequency

Answer 19

A. Select a frequency just below the MUF

Question 20

What is a reliable way to determine if the Maximum Usable Frequency (MUF) is high enough to support skip propagation between your station and a distant location on frequencies between 14 and 30 MHz?

A. Listen for signals from an international beacon

B. Send a series of dots on the band and listen for echoes from your signal

C. Check the strength of TV signals from Western Europe

D. Check the strength of signals in the MF AM broadcast band

Answer 20

A. Listen for signals from an international beacon

Question 21

What usually happens to radio waves with frequencies below the Maximum Usable Frequency (MUF) and above the Lowest Usable Frequency (LUF) when they are sent into the ionosphere?

A. They are bent back to the Earth

B. They pass through the ionosphere

C. They are amplified by interaction with the ionosphere

D. They are bent and trapped in the ionosphere to circle the Earth

Answer 21

A. They are bent back to the Earth

Question 22

What usually happens to radio waves with frequencies below the Lowest Usable Frequency (LUF)?

A. They are bent back to the Earth

B. They pass through the ionosphere

C. They are completely absorbed by the ionosphere

D. They are bent and trapped in the ionosphere to circle the Earth

Answer 22

C. They are completely absorbed by the ionosphere

Question 23

What does LUF stand for?

A. The Lowest Usable Frequency for communications between two points

B. The Longest Universal Function for communications between two points

C. The Lowest Usable Frequency during a 24 hour period

D. The Longest Universal Function during a 24 hour period

Answer 23

A. The Lowest Usable Frequency for communications between two points

Question 24

What does MUF stand for?

A. The Minimum Usable Frequency for communications between two points

B. The Maximum Usable Frequency for communications between two points

C. The Minimum Usable Frequency during a 24 hour period

D. The Maximum Usable Frequency during a 24 hour period

Answer 24

B. The Maximum Usable Frequency for communications between two points

Question 25

What is the approximate maximum distance along the Earth's surface that is normally covered in one hop using the F2 region? A. 180 miles B. 1,200 miles C. 2,500 miles D. 12,000 miles

Answer 25

C. 2,500 miles

Question 26

What is the approximate maximum distance along the Earth's surface that is normally covered in one hop using the E region? A. 180 miles B. 1,200 miles C. 2,500 miles D. 12,000 miles

Answer 26

B. 1,200 miles

Question 27

What happens to HF propagation when the Lowest Usable Frequency (LUF) exceeds the Maximum Usable Frequency (MUF)? A. No HF radio frequency will support ordinary skywave communications over the path B. HF communications over the path are enhanced C. Double hop propagation along the path is more common D. Propagation over the path on all HF frequencies is enhanced

Answer 27

A. No HF radio frequency will support ordinary skywave communications over the path

Question 28

What factors affect the Maximum Usable Frequency (MUF)? A. Path distance and location B. Time of day and season C. Solar radiation and ionospheric disturbances D. All of these choices are correct

Answer 28

D. All of these choices are correct

Question 29

Which of the following ionospheric layers is closest to the surface of the Earth? A. The D layer B. The E layer C. The F1 layer D. The F2 layer

Answer 29

A. The D layer

Question 30

Where on the Earth do ionospheric layers reach their maximum height? A. Where the Sun is overhead B. Where the Sun is on the opposite side of the Earth C. Where the Sun is rising D. Where the Sun has just set

Answer 30

A. Where the Sun is overhead

Question 31

Why is the F2 region mainly responsible for the longest distance radio wave propagation? A. Because it is the densest ionospheric layer B. Because it does not absorb radio waves as much as other ionospheric regions C. Because it is the highest ionospheric region D. All of these choices are correct

Answer 31

C. Because it is the highest ionospheric region

Question 32

What does the term �critical angle� mean as used in radio wave propagation? A. The long path azimuth of a distant station B. The short path azimuth of a distant station C. The lowest takeoff angle that will return a radio wave to the Earth under specific ionospheric conditions D. The highest takeoff angle that will return a radio wave to the Earth under specific ionospheric conditions

Answer 32

D. The highest takeoff angle that will return a radio wave to the Earth under specific ionospheric conditions

Question 33

Why is long distance communication on the 40, 60, 80 and 160 meter bands more difficult during the day? A. The F layer absorbs signals at these frequencies during daylight hours B. The F layer is unstable during daylight hours C. The D layer absorbs signals at these frequencies during daylight hours D. The E layer is unstable during daylight hours

Answer 33

C. The D layer absorbs signals at these frequencies during daylight hours

Question 34

What is a characteristic of HF scatter signals? A. They have high intelligibility B. They have a wavering sound C. They have very large swings in signal strength D. All of these choices are correct

Answer 34

B. They have a wavering sound

Question 35

What makes HF scatter signals often sound distorted? A. The ionospheric layer involved is unstable B. Ground waves are absorbing much of the signal C. The E-region is not present D. Energy is scattered into the skip zone through several different radio wave paths

Answer 35

D. Energy is scattered into the skip zone through several different radio wave paths

Question 36

Why are HF scatter signals in the skip zone usually weak? A. Only a small part of the signal energy is scattered into the skip zone B. Signals are scattered from the magnetosphere which is not a good reflector C. Propagation is through ground waves which absorb most of the signal energy D. Propagations is through ducts in F region which absorb most of the energy

Answer 36

A. Only a small part of the signal energy is scattered into the skip zone

Question 37

What type of radio wave propagation allows a signal to be detected at a distance too far for ground wave propagation but too near for normal sky-wave propagation? A. Faraday rotation B. Scatter C. Sporadic-E skip D. Short-path skip

Answer 37

B. Scatter

Question 38

Which of the following might be an indication that signals heard on the HF bands are being received via scatter propagation? A. The communication is during a sunspot maximum B. The communication is during a sudden ionospheric disturbance C. The signal is heard on a frequency below the Maximum Usable Frequency D. The signal is heard on a frequency above the Maximum Usable Frequency

Answer 38

D. The signal is heard on a frequency above the Maximum Usable Frequency

Question 39

Which of the following antenna types will be most effective for skip communications on 40 meters during the day? A. Vertical antennas B. Horizontal dipoles placed between 1/8 and 1/4 wavelength above the ground C. Left-hand circularly polarized antennas D. Right-hand circularly polarized antenna

Answer 39

B. Horizontal dipoles placed between 1/8 and 1/4 wavelength above the ground

Question 40

Which ionospheric layer is the most absorbent of long skip signals during daylight hours on frequencies below 10 MHz? A. The F2 layer B. The F1 layer C. The E layer D. The D layer

Answer 40

D. The D layer

Question 41

What is Near Vertical Incidence Sky-wave (NVIS) propagation? A. Propagation near the MUF B. Short distance HF propagation using high elevation angles C. Long path HF propagation at sunrise and sunset D. Double hop propagation near the LUF

Answer 41

B. Short distance HF propagation using high elevation angles