Microwave Engineering Lab Viva Questions – Part 8

1. Which of the following does not have 900 phase shift between the output ports

a) Coupled Line Directional Coupler

b) Quadrature Coupler

c) Hybrid Coupler

d) None

Answer : [C] Hybrid Coupler

 

2. Attenuator in a travelling wave tube is used for

A. Attenuating Input signal

B. Avoiding Oscillation

C. Attenuating Output signal

D. Connecting both helix

Answer : [B] Avoiding Oscillation

3. Which are M-type microwave tubes?

A. TWT and Magnetron

B. Klystron and Magnetron

C. TWT and Gyrotron

D. Magnetron and Gyrotron

Answer : [D] Magnetron and Gyrotron

4. Compared to TWT, Klystron has

i. Propagating Field

ii. Non-Propagating field

iii. Small interaction space

iv. Large interaction space

A. I and iv

B. I and iii

C. Ii and iii

D. Ii and iv

Answer : [C] Ii and iii

5. The cut off magnetic field in magnetron is 15mWb/݉ଶ . If the anode voltage V0 is reduced to half of its value, then the cut off magnetic field will be,

A. 30

B. 21

C. 7.5

D. 10.5

Answer : [B] 21

6. In magnetron, near to anode the electron beam has velocity component in

A. phi

B. r‬

C. Z

D. Theta

Answer : [A] phi

7. A helical slow wave structure of diameter 0.5 mm has 20 turns. If the RF input signal travels a distance 30 mm all through the helix, then what is the distance travelled by the axial electric

field.

A. 30.652

B. 10.372

C. 25.815

D. 21.675

Answer : [A] 30.652

8. If the odd mode and even mode impedances are same in a coupled line, it will work as

A. LPF

B. HPF

C. BPF

D. None of these

Answer : [D] None of these

9. By connecting short circuit or open circuit to any two ports of a coupled line, we cannot

implement

A. High pass

B. Low pass

C. Band pass

D. All pass

Answer : [A] High pass

10. Which of the following device is non-reciprocal in nature

a) Quadrature Directional Coupler

b) Hybrid Directional Coupler

c) Bethe Hole Coupler

d) Resistive Power divider

e) None

Answer : [E] None