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ECE Objective Questions { Antenna }



106. In binomial arrays the elimination of secondary lobes takes place
A. at the cost of directivity
B. at the cost of gain
C. both (a) and (b) above
D. none of the above

107. The transmitting antennas for lower frequencies (below 500 kHz) are generally
A. vertically grounded wire type
B. horizontal suspended wire type
C. parabolic reflector type
D. any of the above

108. In Fig. 13.6 the voltage distribution on a vertical earthed antenna is represened by
A. curve A
B. curve B
C. curve C
D. curve D

109.  In the Fig. 13.6 the current distribution is represented by
A. curve A
B. curve B
C. curve C
D. curve D

110. When the height of a vertical earthed antenna is less than ?
A. the base input impedance will be capacitive
B. the base input impedance will be purely resistive
C. the base input impedance will be inductive
D. the base input impedance will be negligibly small

111. For VLF antennas radiation resistance is usually of the order of
A. less than one ohm
B. 13 to 20 ohms
C. around 100 ohms
D. more than 200 ohms

112. A folded dipole antenna is conveniently connected to
A. shielded line
B. two wire line
C. coaxial line
D. flat ribbon type transmission line

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