Electronics and Communication Engineering - Electromagnetic Field Theory

16. 

Zoning is used with a dielectric antenna in order to

A. permit pin-point focusing
B. reduce the bulk of the lens
C. increase the bandwidth of the lens
D. correct the curvature of the wavefront from a horn that is too short

Answer: Option A

Explanation:

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17. 

For aeroplane and navigation frequency band is

A. VLF
B. UHF
C. VHF
D. EHF

Answer: Option B

Explanation:

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18. 

Poynting vector signifies which of the following?

A. Power density vector producing electrostatic field
B. Power density vector producing electromagnetic field
C. Current density vector producing electrostatic field
D. Current density vector producing electromagnetic field

Answer: Option B

Explanation:

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19. 

Which one is correct?

A. Sky wave propagation (2 to 30 MHz)
B. Space wave propagation (> 30 MHz)
C. Tropospheric propagation (> 300 MHz)
D. All of the above

Answer: Option D

Explanation:

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20. 

When a magnetic circuit is compared with an electric circuit, the equivalent of the magnetic flux is

A. the conductivity of the lines
B. the voltage of the source
C. the current in the lines
D. the conductance of the load

Answer: Option C

Explanation:

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