Electronics and Communication Engineering - Communication Systems

46. 

Which of the following is taken as reference antenna for directive gain?

A. Half wave dipole
B. Elementary doublet
C. Isotropic
D. Infinitesimal dipole

Answer: Option C

Explanation:

Isotropic antenna is one which radiates equally in all directions. It is a standard reference antenna.


47. 

Push pull amplifier is

A. voltage amplifier
B. current amplifier
C. power amplifier
D. none of the above

Answer: Option C

Explanation:

Push pull is a power amplifier.


48. 

When the channel is noisy, producing a conditional probability of error p = 0.5; the channel capacity and entropy function would be, respectively,

A. 1 and 1
B. 1 and 0.5
C. 0.5 and 1
D. 0 and 1

Answer: Option D

Explanation:

.


49. 

In CCIR-B system, the time between start of one H syn. pulse and next is

A. 64 μs
B. 6.4 μs
C. 640 μs
D. 0.64 μs

Answer: Option A

Explanation:

The frequency of H pulses is 15625 Hz.

Hence .


50. 

Counterpoise is used in coils having

A. high resistivity
B. low resistivity
C. medium resistivity
D. both (b) and (c)

Answer: Option A

Explanation:

Counterpoise is a horizontally buried wire used to provide low grounding resistance in high resistivity soils.


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