Code: A-19
Subject: ANTENNAS AND WAVE PROPAGATION
Time: 3 Hours
Max. Marks: 100
NOTE: There are 11 Questions in all.  
  • Question 1 is compulsory and carries 16 marks. Answer to Q. 1. must be written in the space provided for it in the answer book supplied and nowhere else.
  • Answer any THREE Questions each from Part I and Part II. Each of these questions carries 14 marks.
  • Any required data not explicitly given, may be suitably assumed and stated
Q.1
Choose the correct or best alternative in the following: (2x8)
 
a.
The magnitude of the velocity of electromagnetic waves reflected from an infinite plane separating two ideal dielectric semi-infinite media
(A) gets multiplied by the reflection coefficient.
(B) gets divided by the reflection coefficient.
(C) remains unchanged.
(D) becomes zero.
 
b.
 The half-wave dipole antenna of the Yagi-Uda antenna, commonly used for receiving TV signals, is folded primarily
(A) To reduce the beamwidth of the antenna.
(B) To increase the maximum directivity of the antenna.
(C) To improve the matching between the antenna and its feeder.
(D) To facilitate its mounting on the boom.
 
c.
 As the main beam of a uniform, equally-spaced linear array is steered from the end-fire direction to the broadside direction by changing the progressive phase shift of the array, it
(A) Becomes broader and broader.
(B) Becomes narrower and narrower.
(C) Remains unchanged.
(D) Becomes broader, attains a minimum and then increases.
 
d.
 Which of the following antennas gives circular polarization?
(A) Helical antenna in its Axial mode.
(B) A single dipole.
(C) Pyramidal Horn antenna.
(D) Yagi-uda antenna.
 
e.
 The radiation pattern of a paraboloidal reflector antenna is
(A) the same as that of the feed antenna.
(B) the square of the feed antenna pattern.
(C) the square root of the feed antenna pattern.
(D) does not depend on the feed antenna pattern.
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