Which of the following is not true with respect to loop antennas? - Avionics MCQ

Aeronautical & Aerospace Engineering : Avionics - Quiz(MCQ)

Which of the following is not true with respect to loop antennas?

A)

Resonance is achieved by a variable capacitor

B)

The horizontal antenna pattern is a figure of eight

C)

The currents are equal in amplitude and phase when the antenna is 90° with the transmitted signal

D)

Horizontal polarization is assumed

Correct Answer : Horizontal polarization is assumed

Explanation : The loop antenna is a rectangular loop of wire whose inductance is resonated by a variable capacitor. The signal is assumed to be vertically polarized and the horizontal antenna pattern is a figure of eight. When the loop is 90° with respect to the transmitted signal the currents induced are of same amplitude and phase.

Recently Updated in Avionics Questions

Which of the following type is not used in an Omega system?

A)

Valley span

B)

Insulated tower

C)

Hanging tower

D)

Grounded tower

Correct Answer : Option (C) : Hanging tower

Explanation : Since the Omega stations transmit in very low frequencies, the antennas are the largest physical structures in the stations. Three types of antennas are employed in the Omega system: grounded tower, insulated tower, and the valley span.

_____ acts as a coarse tuning device for the antenna?

A)

Loop

B)

Helix

C)

Filters

D)

Amplifiers

Correct Answer : Option (B) : Helix

Explanation : The RF signal that is to be transmitted is transferred to the ‘Helix,’ a large helical coil that acts as a coarse tuning device for the antenna. The helix is equipped with separate taps for each signal frequency transmitted.

What type of transmission is used in Omega system?

A)

Phase modulated wave

B)

Continuous wave

C)

Amplitude modulated wave

D)

Frequency modulated wave

Correct Answer : Option (B) : Continuous wave

Explanation : At each Omega station, continuous wave signals on four common frequencies and one station unique frequency. The signal frequencies are time shared among the stations so that a given frequency is transmitted by only one station at any given time.

Advertisement