Transmission Lines and Waveguides MCQs

Question 1

Indicate the FALSE statement regarding ridged waveguides

Accepted Answer

ridged waveguides have less attenuation per unit length than rectangular waveguides

Answer

main effect of adding ridge is to lower the value of cut-off wavelength

Answer

ridges allow a waveguide with smaller dimensions to be used at any given frequency

Answer

ridges reduce the phase velocity

Question 2

The voltage attenuation in dB provided by 20 cm length of a 1 cm x 0.5 cm waveguide in which 1 GHz signal is propagated in dominant mode is

Accepted Answer

545

Answer

272.5

Answer

817.5

Answer

1090

Question 3

After reflection from a plane conducting wall, electromagnetic waves acquire an apparent velocity which is greater than velocity of light in free space. It is called

Accepted Answer

phase velocity

Answer

normal velocity

Answer

group velocity

Answer

velocity of propagation

Question 4

Indicate the FALSE statement When free-space wavelength X, of a signal equals the cut-off wavelength Al of a waveguide, then

Accepted Answer

characteristic wave impedance Zo of the waveguide becomes zero for Tmo mode

Answer

phase velocity of signal becomes infinite

Answer

group velocity of signal becomes zero

Answer

wavelength in the waveguide becomes infinite

Question 5

Point out the FALSE statement. Dominant mode of propagation is preferred with rectangular waveguides because

Accepted Answer

resulting impedance can be matched to the loaddirectly

Answer

it can be propagated in a guide that is too small to propagate any other mode

Answer

there is no energy loss through the spurious generation of other modes

Answer

it is the easiest to excite

Question 6

Indicate the FALSE statement : As compared to rectangular waveguides, circular ones

Accepted Answer

are more difficult to manufacture

Answer

need much bigger cross-sectional area for carrying thesame signal

Answer

have lower attenuation especially at frequencies in excess of 1 GHz

Answer

are easier to join together in the usual plumbing fashion

Question 7

For handling high powers, it is best to use

Accepted Answer

rectangular waveguide

Answer

stripline

Answer

coaxial cable

Answer

microstrip

Question 8

The cavity magnetron employs strapping in order to

Accepted Answer

prevent mode jumping

Answer

reduce frequency pushing and pulling

Answer

ensure bunching

Answer

permit better dissipation of heat

Question 9

Indicate the FALSE statement :Frequency-agile or dither-tuned magnetron

Accepted Answer

can be easily jammed

Answer

has a movable piston for changing its operating frequency

Answer

may be conventional or coaxial

Answer

is capable of sending a series of pulses each of which is at a different frequency