Microwave Communication - ECE Questions and Answers

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If D is diameter of circular waveguide the cutoff wave-length for TE₁₁ mode is equal to

1.706 D

2.11 D

0.82 D

0.41 D

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The external magnetic field in a magnetron is such that lines are

parallel to the axis of cathode

perpendicular to the axis of cathode

inclined to the axis of cathode

either (b) or (c)

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Varactor diodes use

silicon

GaAs

either (a) or (b)

neither (a) nor (b)

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A circular waveguide carries TE₁₁ mode whole radial electric field is given by
E_r = E₀j₁(r) sin Φ V/m
where r is radial distance in cm from the axis
The cut off wavelength is

10 cm

3 p cm

2 p cm

8 cm

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Assertion (A): Impatt diode is an avalanche diode.

Reason (R): Avalanche breakdown phenomenon occurs when a p-n junction is reverse biased.

Both A and R are correct and R is correct explanation of A

Both A and R are correct but R is not correct explanation of A

A is correct but R is wrong

A is wrong but R is correct

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A radar has a maximum range of 120 km. The maximum allowable pulse repetition frequency for unambiguous reception is

1250

330

2500

8330

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In a line with finite attenuation

power transmission is least efficient when there are no standing waves on the line

power transmission is most efficient when there are no standing waves on line

Load power depends on phase constant

standing waves will always exist on the line

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In the given figure a short circuited transmission line resonator If n = 1, 2, 3...

For series reasonance βl = np and for parallel resonance

For series resonance

and for parallel resonance βl = np

βl = np for both series and parallel resonance

for both series and parallel resonance

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The electric field in a TWT due to applied signal

is directed along the helix axis

is directed radially from helix axis

is inclined to the helix axis by about 60°

is inclined to the helix axis by about 45°