# Microwave Engineering Mcqs

Q:

A) 1.06 pW | B) 1.06 fW |

C) 2 µW | D) None of the mentioned |

Answer & Explanation
Answer: B) 1.06 fW

Explanation: The received power by the antenna is given by E²Ae/Zₒ. Substituting the known values in the above equation, the power received is 1.06×10-¹⁵ watts.

Explanation: The received power by the antenna is given by E²Ae/Zₒ. Substituting the known values in the above equation, the power received is 1.06×10-¹⁵ watts.

57

Q:

A) True | B) False |

Answer & Explanation
Answer: A) True

Explanation: Considering distance as a parameter, two types of field zones can be defined around an antenna) .The field near the antenna is called near field or Fresnel region and the other region is the far field that is also called as Fraunhofer region.

Explanation: Considering distance as a parameter, two types of field zones can be defined around an antenna) .The field near the antenna is called near field or Fresnel region and the other region is the far field that is also called as Fraunhofer region.

48

Q:

A) 1.5 | B) 3 |

C) 2.5 | D) 3.5 |

Answer & Explanation
Answer: A) 1.5

Explanation: To find the directivity of the given source, the power radiated by the given source is found out by the method of integration. Taking the ratio of the power radiated by the given source to the power radiated by an isotropic source gives the directivity. Following the above steps, the directivity of the given source is 1.5.

Explanation: To find the directivity of the given source, the power radiated by the given source is found out by the method of integration. Taking the ratio of the power radiated by the given source to the power radiated by an isotropic source gives the directivity. Following the above steps, the directivity of the given source is 1.5.

132

Q:

A) 1 | B) 2 |

C) 3 | D) 4 |

Answer & Explanation
Answer: B) 2

Explanation: Given the directivity of unidirectional power pattern, the directivity of bidirectional power pattern is half of it. Hence the directivity of the source is 2.

Explanation: Given the directivity of unidirectional power pattern, the directivity of bidirectional power pattern is half of it. Hence the directivity of the source is 2.

152

Q:

A) P/ 4πR² | B) P/4π |

C) P/ 4πR | D) P×4πR² |

Answer & Explanation
Answer: A) P/ 4πR²

Explanation: The pointing field vector for an isotropic source is given by the expression P/ 4πR².P is the total power radiated y the source. As the distance of the point from the source increases, the magnitude of pointing vector decreases.

Explanation: The pointing field vector for an isotropic source is given by the expression P/ 4πR².P is the total power radiated y the source. As the distance of the point from the source increases, the magnitude of pointing vector decreases.

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Q:

A) True | B) False |

Answer & Explanation
Answer: A) True

Explanation: All physically realizable, simplest antennas also have directional properties. That is, they radiate energy in one direction than in any other direction. Such sources are called anisotropic point sources.

Explanation: All physically realizable, simplest antennas also have directional properties. That is, they radiate energy in one direction than in any other direction. Such sources are called anisotropic point sources.

53

Q:

A) Isotropic source | B) Anisotropic source |

C) Point source | D) None of the mentioned |

Answer & Explanation
Answer: A) Isotropic source

Explanation: Isotropic source radiates energy in all the direction uniformly. For such a source, the radial component Sr of the pointing vector is independent of θ and φ. The three dimensional power pattern of n isotropic source is a sphere.

Explanation: Isotropic source radiates energy in all the direction uniformly. For such a source, the radial component Sr of the pointing vector is independent of θ and φ. The three dimensional power pattern of n isotropic source is a sphere.

134

Q:

A) 0.4 m² | B) 0.2 m² |

C) 0.1 m² | D) None of the mentioned |

Answer & Explanation
Answer: A) 0.4 m²

Explanation: Given the directivity of the antenna, effective aperture of the antenna is given by Dλ²/4π. substituting the given values of the variables; the effective aperture of the antenna is 0.4 m².

Explanation: Given the directivity of the antenna, effective aperture of the antenna is given by Dλ²/4π. substituting the given values of the variables; the effective aperture of the antenna is 0.4 m².

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