Transmission Lines and Waveguides MCQs

Question 1

Which statement regarding voltage tunable magnetrons (VTMs) is wrong?

Accepted Answer

they use high-Q cavities

Answer

they have an extra injection electrode to help bunching

Answer

their operating frequency can be varied over an octave by adjusting anode votage

Answer

they use cold cathodes

Question 2

The cut-off frequency in a waveguide means

Accepted Answer

longer waves will not propagate significantly

Answer

determine the dimensions of waveguide

Answer

frequency at which no transmission takes place.

Answer

None of above

Question 3

For a standard X-band waveguide of cross-sectional dimension 2.286 cm x 1.016 cm, the cut-off wavelength for a TEio mode is ___ cm.

Accepted Answer

4.572

Answer

2.286

Answer

2.032

Answer

3.02

Question 4

The signal delay caused when a wave travels a distance Z metres through a hollow wave guide is where VPh' V and Vo represent phase gr velocity, group velocity and free space velocity (m/sec) respectively. given by

Accepted Answer

ZN

Answer

Z/Vph

Answer

Z/Vo

Answer

ZN'.V

Question 5

Velocity factor of a transmission lines is 0.8 Electromagnetic waves travel down this line with a velocity of

Accepted Answer

2.4 x 108 m/s

Answer

3 x 108 m/s

Answer

3.75 m/s

Answer

none of these

Question 6

Standing wave ratio (SWR) on a transmission line

Accepted Answer

may be defined as either (a) or (b)

Answer

is directly proportional to the load impedance and inversely proportional to the characteristic impedance is directly proportional to the

Answer

characteristic impedance and inversely proportional to the load impedance

Answer

none of these

Question 7

Two transmission linear have SWRs of (1/6) and 2 respectively

Accepted Answer

The one with SWR = 2 is better matched to the load

Answer

The one with SWR = 1/6 is better matched to the load

Answer

Both are equally well matched

Answer

none of these

Question 8

Standing wave ratio (SWR) equal to unity implies that

Accepted Answer

the transmission line's characteristic impedance equals load impedance

Answer

the transmission line is open circuited

Answer

the transmission line is short circuited

Answer

none of these

Question 9

A transmission line having a reflection co-efficient of (1/3) when terminated in a certain load would have VSVVR of

Accepted Answer

2

Answer

?

Answer

3

Answer

1/3