Electronics and Communication Engineering - Microwave Communication

1. 

The domain mode in rectangular waveguide is

A. TE01
B. TE02
C. TE10
D. TM11

Answer: Option C

Explanation:

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2. 

The reverse voltage applied to a varactor diode

A. is less than avalanche breakdown voltage
B. is more than avalanche breakdown voltage
C. may be more or less than a avalanche breakdown voltage
D. is very high as compared to avalanche breakdown voltage

Answer: Option A

Explanation:

The action of varactor diode is due to the capacitance of depletion layer. The thickness of depletion layer depends on the reverse bias which should not cause breakdown.


3. 

To ensure that only dominant mode TE10 is allowed to propagate in an air filled rectangular waveguide, the lower frequency limit and upper frequency limit are

A. about 25% above fc for TE10 and 5% below fc for TE20 mode respectively
B. about 50% above fc for TE10 and 25% below fc for TE20 mode respectively
C. about 25% above fc for TE10 and 25% below fc for TE20 mode respectively
D. none of the above

Answer: Option A

Explanation:

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4. 

The skin depth at 1000 MHz as compared to that at 500 MHz is

A. 2
B. 12
C. 0.707
D. 0.5

Answer: Option C

Explanation:

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5. 

The transit time (in cycles) for electrons in repeller space of reflex klystron oscillator for sustaining oscillations is (n is any integer)

A. 2(n - 1)
B. 2n - 1
C.
D.

Answer: Option D

Explanation:

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