Ham Radio Technician Test Radio Wave Propagation & Modulation 4

Question 1

What is the approximate height of the F2 ionospheric layer above Earth's surface?

Accepted Answer

200–400 km

Answer

10–15 km

Answer

50–90 km

Answer

600–1000 km

Question 2

What causes 'flutter' in signals received via auroral propagation?

Accepted Answer

The rapid movement and structure of the aurora causing continuously shifting reflection points

Answer

Rapid changes in transmitter power

Answer

Interference from multiple repeaters

Answer

Antenna oscillation in high winds

Question 3

Which type of modulation encodes information by varying the frequency of the carrier wave?

Accepted Answer

Frequency modulation (FM)

Answer

Amplitude modulation (AM)

Answer

Phase modulation (PM)

Answer

Pulse-width modulation (PWM)

Question 4

Why is the 10-meter band generally considered a daytime band during low solar activity?

Accepted Answer

Without adequate F2 ionization, signals are not refracted back to Earth and pass into space

Answer

The band becomes overcrowded at night

Answer

Night-time regulations prohibit 10-meter operation

Answer

The band is used by satellite services at night

Question 5

What is the relationship between frequency and wavelength for radio waves?

Accepted Answer

They are inversely proportional — higher frequency means shorter wavelength

Answer

They are directly proportional — higher frequency means longer wavelength

Answer

They are unrelated

Answer

Wavelength increases with frequency above 30 MHz only

Question 6

What does 'over-deviation' cause in an FM transmission?

Accepted Answer

Splatter into adjacent channels, causing interference to nearby frequencies

Answer

The carrier disappears

Answer

The signal becomes weaker

Answer

The audio becomes quieter than normal

Question 7

During a solar flare, what often happens to HF communication on the sunlit side of Earth?

Accepted Answer

HF signals are absorbed by intense D layer ionization, causing a radio blackout

Answer

HF signals improve dramatically due to increased ionization

Answer

HF signals are redirected to the dark side of Earth

Answer

Solar flares only affect VHF and higher frequencies