Electromagnetic Field Theory - Study Mode

[#141] A loop antenna is a commonly used for
Correct Answer

(B) Direction finding

Explanation

Solution: Option A: Radar Loop antennas are not commonly used for radar systems. Radar systems typically use high-gain antennas such as parabolic reflectors or phased arrays to achieve precise directional transmission and reception. Option B: Direction finding Loop antennas are widely used for direction finding. Their ability to detect the direction of an incoming signal based on variations in induced voltage makes them suitable for this application. This is a key characteristic of loop antennas. Option C: Satellite communication Loop antennas are not ideal for satellite communication. Satellite communication generally requires antennas with high gain and wide coverage, such as parabolic dish antennas, to handle the high-frequency signals and large distances involved. Option D: All of the above While loop antennas are useful for direction finding, they are not commonly used for radar or satellite communication. Thus, this option is incorrect. Conclusion: The correct answer is Option B: Direction finding , as loop antennas are specifically designed and effectively used for detecting the direction of incoming signals.

[#142] Which antenna is a wideband antenna?
Correct Answer

(C) Folded dipole

Explanation

Solution: Option A: Hertz antenna The Hertz antenna, also known as a dipole antenna, operates efficiently over a narrow frequency range. It is not considered a wideband antenna since its bandwidth is limited. Option B: Marconi antenna The Marconi antenna is a type of monopole antenna typically used for narrowband applications. It is not designed to handle a wide range of frequencies, making it unsuitable as a wideband antenna. Option C: Folded dipole The folded dipole is a type of wideband antenna. Its construction allows it to operate over a broader frequency range compared to standard dipole antennas. This characteristic makes it suitable for applications requiring wideband operation. Option D: None of the above This option is incorrect because the folded dipole antenna is explicitly a wideband antenna. Therefore, this statement does not apply. Conclusion: The correct answer is Option C: Folded dipole , as it is specifically designed to function as a wideband antenna.

[#143] The potential that appears at a point in space due to the current which caused it is called potential
Correct Answer

(B) Retardation

[#144] The minimum height of outer atmosphere is
Correct Answer

(D) 400 km

[#145] The radiation pattern of a parabola antenna is
Correct Answer

(C) Highly directional