DGCA Air Navigation: Radio Wave Fundamentals Questions
173 exam-style Radio Wave Fundamentals questions for the DGCA Air Navigation paper (CPL · ATPL · PPL). The first 12 are free below with answers and explanations — sign up free to practise all of them with progress tracking.
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Q1
A radio beacon has an operational range of 10 NM. By what factor should the transmitter power be increased in order to achieve an operational range of 20 NM?
- A Four
- B Six
- C Eight
- D Two
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Correct answer: A. Four
Radio range varies with the square root of transmitter power, so to double the operational range the power must be increased by a factor of four. Quadrupling power doubles the distance at which the same field strength is received.
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Q2
What is the wavelength of an NDB transmitting on 375 kHZ?
- A 800 m
- B 8000 m
- C 8 m
- D 80 m
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Correct answer: A. 800 m
Wavelength equals the speed of light divided by frequency, so 300 million metres per second divided by 375 000 Hz gives 800 metres. This places the beacon firmly in the low/medium frequency band used for NDBs.
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Q3
A radio wave is:
- A an energy wave comprising an electrical field in the same plane as a magnetic field
- B an electrical field alternating with a magnetic field
- C an energy wave where there is an electrical field perpendicular to a magnetic field
- D an energy field with an electrical component
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Correct answer: C. an energy wave where there is an electrical field perpendicular to a magnetic field
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Q4
The process which causes the reduction in signal strength as range from a transmitter increases is known as:
- A absorption
- B diffraction
- C attenuation
- D ionisation
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Correct answer: C. attenuation
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Q5
he bandwidth produced when a radio frequency (RF) of 4716 kHz is amplitude modulated with an audio frequency of 6 khz is
- A 6 kHz
- B 3 kHz
- C 12 kHz
- D 9 kHz
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Correct answer: C. 12 kHz
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Q6
The ideal length for a Marconi aerial for a frequency of 406 MHz is:
- A 36.9 cm
- B 35.1 cm
- C 17.5 cm
- D 18.5 cm
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Correct answer: D. 18.5 cm
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Q7
The speed of radio waves is:
- A 300 km per second
- B 300 million metres per second
- C 162 nm per second
- D 162 million nm per second
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Correct answer: B. 300 million metres per second
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Q8
Which of the following will give the greatest surface wave range?
- A 243 MHz
- B 500 kHz
- C 2182 khz
- D 15 MHz
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Correct answer: B. 500 kHz
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Q9
Which of the following statements concerning AM is correct?
- A the amplitude of the RF is modified by the frequency of the AF
- B the amplitude of the RF is modified by the amplitude of the AF
- C the frequency of the RF is modified by the frequency of the AF
- D the frequency of the RF is modified by the amplitude of the AF
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Correct answer: B. the amplitude of the RF is modified by the amplitude of the AF
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Q10
A disadvantage of directivity is:
- A reduced range
- B sidelobes
- C phase distortion
- D ambiguity
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Correct answer: B. sidelobes
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Q11
The plane of polarisation of an electromagnetic wave is:
- A the plane of the magnetic field
- B the plane of the electrical field
- C the plane of the electrical or magnetic field dependent on the plane of the aerial
- D none of the above
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Correct answer: B. the plane of the electrical field
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Q12
It is intended to increase the range of a VHF transmitter from 50 nm to 100 nm. This will be achieved by increasing the power output by a factor of:
- A 2
- B 8
- C 16
- D 4
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Correct answer: D. 4
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