Electronics and Communication Engineering - Microwave Communication

21. 

In which of the following devices can the operation be visualised in terms of a series feedback loops?

A. TWT
B. Reflex klystron
C. Klystron amplifier
D. Backward wave oscillator

Answer: Option D

Explanation:

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22. 

The first and second subscripts in models of circular waveguides depict

A. the number of full sine wave variations in circumference in direction and Bessel function variations in radial direction respectively
B. the Bessel function variations in radial direction and the number of full sine wave variations in circumference direction respectively
C. the Bessel function variations in circumference direction and number of full sine wave variations in radial direction respectively
D. none of the above

Answer: Option A

Explanation:

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23. 

In which mode of circular waveguide does the attenuation continuously decrease as frequency is increased?

A. TE01
B. TE11
C. TE05
D. TE21

Answer: Option A

Explanation:

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24. 

In which mode of rectangular waveguide are all field components zero?

A. TM00
B. TM11
C. TM01
D. TM10

Answer: Option A

Explanation:

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25. 

A microstrip line has dielectric having relative permittivity ∈r. The effective dielectric constant is

A. more than ∈r
B. equal to 1
C. less than ∈r
D. either a or b

Answer: Option C

Explanation:

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