Microwave Devices and Circuits MCQs

Question 1

The primary purpose of the helix in a travelling-wave tube is to

Accepted Answer

reduce the axial velocity of the FR field

Answer

prevent the electron beam from spreading in the long tube

Answer

ensure broadband operation

Answer

reduce the noise figure.

Question 2

A helical antenna is used for satellite tracking because of its

Accepted Answer

circular polarization

Answer

brod bandwidth

Answer

maneuverability

Answer

good front-to-back ratio

Question 3

Cassegrain feed is used with a parabolic reflector to

Accepted Answer

allow the feed to be placed at a convenient point

Answer

increase the gain of the system

Answer

increase the beamwidth of the system

Answer

reduce the size of the main reflector

Question 4

Indicate the FALSE statement. The parabolic reflector is

Accepted Answer

omnidirectional antenna

Answer

pencil beam antenna

Answer

popularly used antenna is terrestrial line-of-sight communication

Answer

not a broadcast antenna

Question 5

An antenna that is circularly polarized is the

Accepted Answer

helical

Answer

small circular loop

Answer

parabolic reflector

Answer

circular horn

Question 6

A geostationary satellite

Accepted Answer

is not really stationary at all but orbits the earth with a 24 hrs period

Answer

is motionless in space (except for its spin)

Answer

is located at a height of approximately 36,000 km to ensure global coverage

Answer

appears stationary over the earth's magnetic dipole

Question 7

The voice channel bandwidth b, according to CCIR recommendation, is ____ kHz.

Accepted Answer

3.1

Answer

4

Answer

4.2

Answer

2.5

Question 8

A superheterodyne receiver with an IF of 450 kHz is tuned to a signal at 1200 kHz. The image frequency is ___ kHz.

Accepted Answer

2100

Answer

750

Answer

300

Answer

1650

Question 9

Microwave communication uses

Accepted Answer

paraboloidal antennas

Answer

long-wave antennas

Answer

rhombic antennas

Answer

lobe antennas