250+ TOP MCQs on Radio Shop – HF and Answers

Aircraft Maintenance Multiple Choice Questions on “Radio Shop – HF”.

1. What is the full form of MUF?
a) Most usable frequency
b) Minimum usable frequency
c) Maximum usable frequency
d) Minimal usable frequency
Answer: c
Clarification: MUF refers to Maximum usable frequency. The maximum usable frequency is dependent on the angle of incidence of the waves and thus keeps on changing.

2. Which of the following is not a factor influencing HF propagation?
a) Wind speed
b) Season
c) Solar activity
d) Sunspot cycle
Answer: a
Clarification: Wind speed is not a factor influencing HF propagation. However, season, solar activity and sunspot cycle along with other factors influence HF propagation.

3. The High frequency band is also known as ___________
a) Pentameter band
b) Decameter band
c) Quadmeter band
d) Hexameter band
Answer: b
Clarification: The High frequency (HF) Band is also known as the Decameter band. This is because of the wavelengths in this band range from one to ten decameters.

4. Communication at high frequencies is often called as ____________
a) Longwave radio
b) Ultra shortwave radio
c) Shortwave radio
d) Mediumwave radio
Answer: c
Clarification: Communication at high frequencies is often called shortwave radio. This is because the HF band is a major part of the shortwave band of frequencies.

5. What is the wavelength range of HF?
a) 100km to 10km
b) 1000m to 100m
c) 1000km to 100km
d) 100m to 10m
Answer: d
Clarification: 100m to 10m is the wavelength range of HF. These frequencies are suitable for long-distance communication across intercontinental distances.

6. Frequencies immediately below HF are referred to as _______
a) Medium frequency
b) Ultra high frequency
c) Low frequency
d) Ultra low frequency
Answer: a
Clarification: The frequencies immediately below HF are referred to as Medium frequency. The medium frequency band also comprises of the medium wave band, used specifically for broadcasting AM.

7. What is the frequency range of HF (High frequency)?
a) 3 MHz to 30 MHz
b) 3 Hz to 30 Hz
c) 3 KHz to 30 KHz
d) 3 mHz to 30 mHz
Answer: a
Clarification: High frequency refers to the radio frequency range lying between 3 MHz to 30 MHz. These waves possess wavelengths from one to ten decameters and the band is thus referred to as the decameter band.

8. What is the full form of FOT?
a) Frequency of open transmission
b) Frequency of optimum transmission
c) Frequency of optical transmission
d) Frequency of optional transmission
Answer: b
Clarification: FOT refers to the Frequency of optimum transmission. It is the highest effective frequency, predicted to be useful for a specified path in the transmission of radio waves, via ionospheric reflection.

9. The lowest usable frequency depends on the absorption of which of the following layers?
a) D-layer
b) E-layer
c) F-layer
d) G-layer
Answer: a
Clarification: The lowest usable frequency depends on the absorption of the D-layer. The D-layer is the lower layer of the ionosphere and lies beneath the E-layer.

10. In aviation, HF communication systems are required for all trans-oceanic flights.
a) False
b) True
Answer: b
Clarification: True. In aviation, HF communication systems are required for all trans-oceanic flights. This is because HF is suitable for long-distance communication and for mountainous terrains.

11. On a day in full summer the __________ tend to be more usable.
a) Ultra low frequencies
b) Medium frequencies
c) Lower frequencies
d) Higher frequencies
Answer: d
Clarification: On a day in full summer the higher frequencies tend to be more usable. This is because of the MUF and LUF phenomenon, which depend on the angle of incidence of the waves.

12. What is the full form of RFID?
a) Real frequency identification
b) Radar frequency identification
c) Radio frequency identification
d) Rate frequency identification
Answer: c
Clarification: RFID refers to radio frequency identification. The RFID tags use High Frequency (HF). These tags are commonly known as High-Frequency Identification or HFIDs.

13. Which of the following is referred to as the upper section of HF?
a) 26.5 MHz to 30 MHz
b) 26.5 Hz to 30 Hz
c) 265 MHz to 300 MHz
d) 265 Hz to 300 Hz
Answer: a
Clarification: The upper section of high frequency range refers to frequencies having a magnitude between 26.5 MHz and 30 MHz. Frequencies from this section possess characteristics similar to frequencies in the lower part of VHF.

14. The MUF is lowest when the waves are directed ___________
a) Straight downwards
b) Straight upwards
c) Diagonally
d) Incidentally
Answer: b
Clarification: The maximum usable frequency is lowest when the waves are directed straight upwards, and it is higher with less acute angles. This means that at longer distances, the MUF might be much higher.

15. HF radio waves can travel beyond the horizon.
a) False
b) True
Answer: b
Clarification: True, HF radio waves can travel beyond the horizon. These waves can travel around the curve of the earth, however its suitability is dependent on various complex factors.