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ECE Objective Questions { Antenna }



113. Antenna radiation effeciency can be increased by
A. reducing radiation resistance of the system
B. increasing radiation resistance of the system
C. providing effective earthing
D. any of the above

114. The effective height of an antenna is slightly greater than physical height because
A. wave velocity in conductor is less than its velocity in free space
B. wave velocity in conductor is more than its velocity in free space
C. resistance of conductor is less than that of free space
D. none of the above

115. The advantage of Marconi antenna over the ungrounded antenna is that
A. only one fourth of the height is required as compared to undergrounded antenna
B.one half of the height is required as compared to ungrounded antenna
C. no capacitance that is required
D. none of the above

116. In series excitation of a tower antenna
A. voltage is applied between the upper part of the vertical radiator and tower is insulated from ground
B.voltage is applied between the lower part of the vertical radiator and tower is insulated from ground
C. voltage is applied only to the top T conductor and tower is insulated from ground.
D. none of the above

117. Induction and radiation fields are equal at a distance equal to 6
A. 7,
B. 6 X
C.X
D.(c) ? 6

118. The effective length of a tower radiator is
A.2n
B. le =21
C. = it
D. none of the above

119. Which of the following antenna is best guided by a waveguide?
A. Biconical
B. Horn
C. Helical
D. Discone

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