# Micro Wave Engineering 3

Electronic Engineering MCQ Question Papers: ENTC, IT Interview Placement

Subject: Micro Wave Engineering 3

Part 3: List for questions and answers of Micro Wave Engineering

Q1. In a loss line rl les then z0, then

a) Reflection coefficient is zero

b) Reflection coefficient is 8

c) Reflection coefficient is negative

d) Reflection coefficient is positive

Q2. Assertion (a): a backward wave oscillator can be used as a sweep generator Reason (r): the frequency of oscillation of a backward wave oscillator can be changed by varying the voltage which controls the beam velocity.

a) Both a and r are correct and r is correct explanation of a

b) Both a and r are correct but r is not correct explanation of a

c) A is correct but r is wrong

d) A is wrong but r is correct

Q3. A transmission line has z0 = 300Ω  and zl = (300 – j300) ohm. The transmission

coefficient is

a) 1.265   – 18.43°

b) 1.01   – 10°

c) 1.14   66.68°

d) 1.09   66.68°

Q4. In a reflex klystron oscillator, repeller electrode is at

a) Low positive potential

b) High positive potential

c) Negative potential

d) Zero potential

Q5. A quarter wave line short circuited at load end behaves as

a) An inductance

b) An inductance and capacitance in series

c) A capacitance

d) An inductance and capacitance in parallel

Q6. A (75 – j50) ohm load is connected to a coaxial of z0 = 75 ohm at 10 ghz. The best method of matching is to connect

b) A short circuited stub at load

c) A short circuited stub at specific distance from load

d) A capacitance at specific distance from load

Q7. The width of a radio beam from a 1 m diameter parabolic antenna at 1 ghz is about

a) 100°

b) 50°

c) 5°

d) 2°

Q8. Which one of the following is transferred locking electron device c antenna?

a) Baritt diode

b) Impatt diode

c) Gunn diode

d) Step recovery diode

Q9. When a line short circuited at far end, the minimum voltage occurs at

a) Far end

b) Source end

c) Midway between source and far end

d) None of the above

Q10. In a twt the axial component of electric field advances along the tube

a) At a velocity that is almost equal to speed of light

b) At a velocity that is a small fraction of speed of light

c) At a velocity that is about 50% of speed of light

d) At a velocity that may be even more than speed of light

Q11. If other parameter are constant, transmission loss at 5 ghz as compared to that at 0.5 ghz is

a) 20 db more

b) 20 db less

c) 700 db more

d) 100 db less

Q12. For a circular wave guide

a) Cutoff frequency for te10 and te01 modes are same

b) Cutoff frequency for te10 and te01 modes are different

c) Cutoff frequency for te10 mode = twice the cutoff frequency for te20 mode

d) Cutoff frequency for te10 mode = haf the cutoff frequency for te20 mode

Q13. The magnitudes of oc and sc input impedances of a transmission line an 100 ohm and 25 ohm. The characteristic impedance is

a) 25 ohm

b) 50 ohm

c) 75 ohm

d) 100 ohm

Q14. A loss less line is terminated in a circular lines are e lines

a) Swr = 0

b) Swe = 0

c) Swr is finite

d) Swr = 8

Q15. Which of the following terminations makes the input impedance of a line equal to characteristic impedance z0?

a) Line open circuited at far end

b) Line terminated in z0

c) Line short circuited at far end

d) Line terminated in inductance

Q16. In microwave system the function of mode filter is

a) To suppress modes with lower cut off frequencies

b) To suppress modes with higher cut off frequencies

c) To change mode of wave transmission

d) Both (b) and (c)

Q17. The total field developed by an antenna array at a distant point is

a) Phasor sum of fields produced by individual antennas of the array

b) Algebraic sum of fields produced by individual antennas of the array

c) Either (a) or (b) depending on type of array

d) Neither (a) nor (b)

Q18. High speed logic circuits use

a) Pulses with very small width

b) Pulses with very large width

c) Pulses whose width is neither small nor large

d) Either (b) or (c)

Q19. To couple a coaxial line to a parallel wire line it is best to use

a) Slotted line

b) Balun

c) Directional coupler

d) λ /4 transformer

Q20. Assertion (a): a quarter wave transformer is used to match a resistive load to a transmission line Reason (r): a quarter wave transformer is a transmission line of quarter wave length

a) Both a and r are correct and r is correct explanation of a

b) Both a and r are correct but r is not correct explanation of a

c) A is correct but r is wrong

d) A is wrong but r is correct

Part 3: List for questions and answers of Micro Wave Engineering