Electronics and Communication Engineering - Electromagnetic Field Theory

41. 

The effective height of a vertical radiator can be increased by

A. loading with lumped inductance
B. supporting on an insulator
C. capacitive loading
D. giving input more power

Answer: Option C

Explanation:

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42. 

When an electromagnetic wave travelling in one medium strikes upon a second medium (having a different conductivity) the wave will be

A. totally transmitted
B. totally reflected
C. neither transmitted nor reflected
D. partially transmitted and partially reflected

Answer: Option D

Explanation:

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43. 

For transmission of waveform a dielectric medium of permittivity ε1 into a dielectric medium of lower permittivity ε2 , (ε1 > ε2) the critical angle of incidence θc (relative to the interface) is given by

A. sin-1
B. cos-1
C. tan-1
D.

Answer: Option C

Explanation:

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44. 

The line of sight communication requires that transmit and receive antennas to face each other. If the transmit antenna is vertically polarized, for the best reception the receive antenna should be

A. horizontally polarized
B. vertically polarized
C. at 45° with respect to horizontal polarization
D. at 45° with respect to vertical polarization

Answer: Option A

Explanation:

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45. 

An antenna has 40 Ω resistance and 60 Ω radiation resistance. The efficiency of the antenna is

A. 30%
B. 40%
C. 50%
D. 60%

Answer: Option D

Explanation:

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