www.WH6FQE.com

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

 

​

​

G3A – Sunspots and solar radiation; ionospheric disturbances; propagation forecasting and indices

 

​

G3A01

What is the significance of the sunspot number with regard to HF propagation?

A. Higher sunspot numbers generally indicate a greater probability of good propagation at higher frequencies

B. Lower sunspot numbers generally indicate greater probability of sporadic E propagation

C. A zero sunspot number indicates that radio propagation is not possible on any band

D. A zero sunspot number indicates undisturbed conditions

~~

 

 

G3A02

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

~~

 

 

G3A03

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

A. 28 days

B. 1 to 2 hours

C. 8 minutes

D. 20 to 40 hours

~~

 

 

G3A04

Which of the following are least reliable for long-distance communications during periods of low solar activity?

A. 80 meters and 160 meters

B. 60 meters and 40 meters

C. 30 meters and 20 meters

D. 15 meters, 12 meters, and 10 meters

~~

 

 

G3A05

What is the solar flux index?

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

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

C. Another name for the American sunspot number

D. A measure of solar radiation at 10.7 centimeters wavelength

~~

 

 

G3A06

What is a geomagnetic storm?

A. A sudden drop in the solar flux index

B. A thunderstorm that affects radio propagation

C. Ripples in the ionosphere

D. A temporary disturbance in Earth’s magnetosphere

~~

 

 

G3A07

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

~~

 

 

G3A08

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

A. Improved high-latitude HF propagation

B. Degraded high-latitude HF propagation

C. Improved ground wave propagation

D. Degraded ground wave propagation

~~

 

 

G3A09

What benefit can high geomagnetic activity have on radio communications?

A. Auroras 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

~~

 

 

G3A10

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

A. Long term oscillations in the upper atmosphere

B. Cyclic variation in Earth’s radiation belts

C. The sun’s rotation on its axis

D. The position of the moon in its orbit

~~

 

 

G3A11

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

A. 28 days

B. 14 days

C. 4 to 8 minutes

D. 20 to 40 hours

~~

 

 

G3A12

What does the K-index indicate?

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

B. The short-term stability of Earth’s magnetic field

C. The stability of the sun’s magnetic field

D. The solar radio flux at Boulder, Colorado

~~

 

 

G3A13

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 Earth’s geomagnetic field

D. The solar radio flux at Boulder, Colorado

~~

 

 

G3A14

How are radio communications usually affected by the charged particles that reach 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

~~

 

 

​

G3B – Maximum Usable Frequency; Lowest Usable Frequency; propagation

 

​

G3B01

What is a characteristic of skywave signals arriving at your location 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 slightly delayed echo might be heard

~~

 

 

G3B02

What factors affect the MUF?

A. Path distance and location

B. Time of day and season

C. Solar radiation and ionospheric disturbances

D. All these choices are correct

~~

 

 

G3B03

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

~~

 

 

G3B04

What is a reliable way to determine if the 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 in the frequency range you plan to use

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

~~

 

 

G3B05

What usually happens to radio waves with frequencies below the MUF and above the LUF when they are sent into the ionosphere?

A. They are bent back to 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 Earth

~~

 

 

G3B06

What usually happens to radio waves with frequencies below the LUF?

A. They are bent back to 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 Earth

~~

 

 

G3B07

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

~~

 

 

G3B08

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

~~

 

 

G3B09

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

~~

 

 

G3B10

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

~~

 

 

G3B11

What happens to HF propagation when the LUF exceeds the 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

~~

 

 

​

G3C – Ionospheric layers; critical angle and frequency; HF scatter; Near Vertical Incidence Skywave

 

​

G3C01

Which ionospheric layer is closest to the surface of Earth?

A. The D layer

B. The E layer

C. The F1 layer

D. The F2 layer

~~

 

 

G3C02

Where on Earth do ionospheric layers reach their maximum height?

A. Where the sun is overhead

B. Where the sun is on the opposite side of Earth

C. Where the sun is rising

D. Where the sun has just set

~~

 

 

G3C03

Why is the F2 region mainly responsible for the longest distance radio wave propagation?

A. Because it is the densest ionospheric layer

B. Because of the Doppler effect

C. Because it is the highest ionospheric region

D. Because of meteor trails at that level

~~

 

 

G3C04

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 Earth under specific ionospheric conditions

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

~~

 

 

G3C05

Why is long-distance communication on the 40-meter, 60-meter, 80-meter, 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

~~

 

 

G3C06

What is a characteristic of HF scatter?

A. Phone signals have high intelligibility

B. Signals have a fluttering sound

C. There are very large, sudden swings in signal strength

D. Scatter propagation occurs only at night

~~

 

 

G3C07

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

~~

 

 

G3C08

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. Propagation is through ducts in the F region, which absorb most of the energy

~~

 

 

G3C09

What type of propagation allows signals to be heard in the transmitting station’s skip zone?

A. Faraday rotation

B. Scatter

C. Chordal hop

D. Short-path

~~

 

 

G3C10

What is Near Vertical Incidence Skywave (NVIS) propagation?

A. Propagation near the MUF

B. Short distance MF or HF propagation using high elevation angles

C. Long path HF propagation at sunrise and sunset

D. Double hop propagation near the LUF

~~

 

 

G3C11

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

~~