Ham Radio Technician Test Radio Wave Propagation & Modulation 3

Question 1

What happens to the MUF (Maximum Usable Frequency) when solar activity decreases?

Accepted Answer

MUF decreases because the ionosphere is less ionized

Answer

MUF increases because the ionosphere is less disturbed

Answer

MUF stays the same regardless of solar activity

Answer

MUF only changes at night

Question 2

What is the purpose of a CTCSS tone on an FM transmission?

Accepted Answer

To access repeaters or squelch a receiver only when the correct tone is present

Answer

To increase transmitter power

Answer

To modulate the carrier for better audio quality

Answer

To identify the transmitting station automatically

Question 3

Why does AM voice occupy more bandwidth than SSB?

Accepted Answer

AM transmits both sidebands plus a full carrier, while SSB suppresses one sideband and the carrier

Answer

AM uses a higher carrier frequency

Answer

AM modulates at a higher audio frequency

Answer

AM requires a larger antenna

Question 4

What is multipath propagation?

Accepted Answer

Signals arriving at a receiver via two or more different paths, causing interference

Answer

Signals that travel through multiple ionospheric layers simultaneously

Answer

Using two separate antennas to send the same signal

Answer

A propagation mode that works on multiple frequency bands

Question 5

At what time of day is the D layer absorption of HF signals greatest?

Accepted Answer

Local noon when solar radiation is strongest

Answer

Just before sunrise

Answer

Midnight when the ionosphere is most stable

Answer

Early morning when the E layer is active

Question 6

What does the term 'skip zone' mean in HF propagation?

Accepted Answer

The area where ground wave coverage ends and sky wave coverage begins, with no coverage in between

Answer

A region of heavy ionospheric absorption

Answer

The distance between two ionospheric reflection points

Answer

The area covered by tropospheric ducting

Question 7

Which emission type is most efficient for weak-signal HF communication when bandwidth is limited?

Accepted Answer

Single sideband suppressed carrier (SSB)

Answer

AM double-sideband full carrier

Answer

Frequency modulation (FM)

Answer

On-off keying (OOK)