Transmission Lines and Waveguides MCQs

Question 1

Waveguides are used mainly for microwave signals because

Accepted Answer

the would be too bulky at lower frequencies

Answer

they depend on straight-line propagation which applies to microwaves only

Answer

losses would be too heavy at lower frequencies

Answer

there are no generators powerful enough to excite them at lowe frequencies

Question 2

A rectangular waveguide 2.29cm x 1.02 cm operates at a frequency of 11 GHz in TElo mode. If the maximum potential gradient of thesignal is 5 kV/cm, then the maximum power handling capacity of the waveguide will be

Accepted Answer

31.11 kW

Answer

31.11mW

Answer

31.1IW

Answer

31.11 MW

Question 3

A cavity resonator can be represented by

Accepted Answer

an LCR circuit

Answer

an LC circuit

Answer

a lossy inductor

Answer

a lossy capacitor

Question 4

The cut-off wavelength Xc for TE20 mode for a standdrd rectangular waveguide is

Accepted Answer

a

Answer

2/a

Answer

2a

Answer

2a2

Question 5

In an air line, adjacent maxima are found at 12.5 cm and 37.5 cm. The operating frequency is

Accepted Answer

600 MHz

Answer

1.5 GHz

Answer

300 MHz

Answer

1.2 GHz

Question 6

The degenerate modes in a waveguide are characterised by

Accepted Answer

same cut-off frequencies but different field distributions

Answer

same cut-off frequencies and same field distributions

Answer

different cut-off frequencies but same field distributions

Answer

different cut-off frequencies and different field distributions

Question 7

For TM waves in a parallel plate waveguide, the minimum attenuation arising from imperfect conductors would occur at a frequency of (fc is the cut-off frequency)

Accepted Answer

fc

Answer

3fc

Answer

2fc

Question 8

For a rectangular waveguide (a x b, a> b) to suport only the TE10 mode at wave length which one of the following pairs of inequalities is to be satisfied?

Accepted Answer

a < X <2b; X <2a

Answer

b < X< 2b; X > 2a

Answer

b < X < 2b; X < 2a

Answer

a < X <2b; X >2a

Question 9

In a hollow rectangular waveguide, the phase velocity

Accepted Answer

decrease with increasing frequency

Answer

increases with increasing frequency

Answer

is independent of frequency

Answer

will vary with frequency depending upon the frequency range