Olete.in – MCQs, Mock Tests & Government Job Prep | Electrical engineering Microwave Engineering MCQs Set-1

The value of ‘α’ for a lossless line is:

1. 0
2. 1
3. Infinity
4. Data insufficient

✅ Correct Answer: 1

If propagation constant is 12:60°, then the value of phase constant and attenuation constant is:

1. α=6, β=10.39
2. α=61, β=78
3. α=12, β=20.6
4. none of the mentioned

✅ Correct Answer: 1

If a transmission line with inductive reactance of 41.97 Ω and capacitive reactance of 1132.5Ω is operated at 1 GHz , then its phase constant is:

1. 0.0305
2. 0.3
3. 30.3
4. 0.6

✅ Correct Answer: 1

If the admittance and the impedance of a transmission line are 100 Ω and 50 Ω of a respectively, then value of phase constant β is:

1. 0
2. 20
3. 132
4. 50

✅ Correct Answer: 1

For a lossless line, which of the following is true?

1. γ=jβ
2. γ=α
3. γ=α+jβ
4. γ=α*jβ

✅ Correct Answer: 1

Expression for phase constant β is:

1. √LC
2. ω √LC
3. 1/ (ω √LC)
4. None of the mentioned

✅ Correct Answer: 2

A microwave generator at 1.2 GHz supplies power to a microwave transmission line having the parameters R=0.8Ω/m, G=O.8millisiemen/m, L=0.01µH/m and C=0.4PF/m. Propagation constant of the transmission line is:

1. 0.0654 +j0.48
2. 0.064+j4.8
3. 6.4+j4.8
4. none of the mentioned

✅ Correct Answer: 1

In a certain microwave transmission line, the characteristic impedance was found to be 210 10°Ω and propagation constant 0.2 78°.What is the impedance Z of the line, if the frequency of operation is 1 GHz?

1. 0.035+j41.97
2. 0.35+j4.97
3. 35.6+j4.28
4. 9.254+j4.6

✅ Correct Answer: 1

For a transmission line, L=1.8mh/m C=0.01pF/m, then the phase constant of the line when operated at a frequency of 1 GHz is:

1. 4.2426
2. 2.2
3. 0.3
4. 1

✅ Correct Answer: 1

In a two wire transmission line, if the distance between the lines is 20 mm and the radii is 5 mm then the inductance of the line is:

1. 0.1 µH
2. 0.526 µH
3. 0.9 µH
4. 1 µH

✅ Correct Answer: 2

In a two wire transmission line , if the distance between the lines is 60mm and the radii is 10 mm , then the capacitive reactance of the line when operated at 12.5 GHz is

1. 20 pF
2. 21.13 pF
3. 23 pF
4. 12 pF

✅ Correct Answer: 2

The wave impedance of air for a wave propagating in it is:

1. 377 Ω
2. 345 Ω
3. Insufficient data
4. None of the mentioned

✅ Correct Answer: 1

Wave impedance of a wave travelling in a medium of a relative permittivity 2 and permeability 4 is

1. 188.5 Ω
2. 200 Ω
3. 300 Ω
4. None of the mentioned

✅ Correct Answer: 1

For a parallel plate transmission line, if w= 12 mm and the distance between the plates is 2 mm, then the inductance of the transmission line is:

1. 0.2 µH
2. 0.1 µH
3. 0.3 µH
4. 0.4 µH

✅ Correct Answer: 1

If the distance between the 2 wires in a 2 wire transmission line is 10 mm and the radii 2 mm, then the inductance of the transmission line is:

1. 0.62 µH
2. 1 µH
3. 2 µH
4. None of the mentioned

✅ Correct Answer: 1

For a parallel plate transmission line, if the complex part of permittivity is 2.5, if the width is 100 mm and the distance between the plates is 10 mm, then the conductance of the transmission line is:

1. 25 Ʊ
2. 30 Ʊ
3. 45 Ʊ
4. None of the mentioned

✅ Correct Answer: 1

For a parallel plate transmission line, if the series resistance is 10 mΩ/m, and the width is 100 mm, then the resistance of the transmission line is:

1. 0.2 Ω
2. 1 Ω
3. 2 Ω
4. 5 Ω

✅ Correct Answer: 1

If the outer and the inner diameter of a coaxial transmission line are 20 mm and 10 mm respectively, then the inductance /m of the transmission line is:

1. 0.13 µH
2. 0.2 µH
3. 0.3 µH
4. 0.1 µH

✅ Correct Answer: 1

If the outer circumference and the inner circumference of a transmission line are 40π and 25π units respectively, then the capacitive reactance of the coaxial transmission line is:

1. 0.376 nF
2. 0.45 nF
3. 0.9 nF
4. none of the mentioned

✅ Correct Answer: 1

For a 2 wire transmission line, if the complex part of permittivity is 2.5, then the given distance between the 2 wires is 10mm and operated at a frequency of 1.2 MHz and the radius of the line being 5mm, then the conductance of the transmission line is:

1. 0.2 µH
2. 0.1 µH
3. 0.5 µH
4. 1 µH

✅ Correct Answer: 1

Characteristics impedance of a coaxial line with external and inner diameter 5mm is:

1. 40 Ω
2. 41.58 Ω
3. 47.78 Ω
4. 54.87 Ω

✅ Correct Answer: 2

The characteristic impedance of the transmission line if the outer diameter and inner diameter of the transmission line is 20 mm and 10 mm respectively, given the intrinsic impedance of the medium is 377 Ω, then the characteristic impedance of the transmission line is:

1. 41.58 Ω
2. 50 Ω
3. 377 Ω
4. None of the mentioned

✅ Correct Answer: 1

Flow of power in transmission line takes place through:

1. Electric field and magnetic field
2. Voltage and current
3. Voltage
4. Electric field

✅ Correct Answer: 1

When a transmission line is exited by a source, total power supplied is delivered to the load.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Input impedance of a transmission line can be represented in terms of this simple trigonometry function.

1. sine function
2. cosine function
3. cotangent function
4. tangent function

✅ Correct Answer: 4

Input impedance of a open circuited transmission line is represented using this trigonometric function:

1. sine function
2. cosine function
3. cotangent function
4. tangent function

✅ Correct Answer: 3

For a λ/2 transmission line, if the characteristic impedance of the line is 50 Ω and the terminated with a load of 100 Ω, then its input impedance is:

1. 100Ω
2. 50Ω
3. 88.86Ω
4. none of the mentioned

✅ Correct Answer: 1

If a λ/3 transmission line is open circuited and has characteristic impedance of 50 Ω then the input impedance is:

1. j28.86Ω
2. 50Ω
3. j50Ω
4. 28.86Ω

✅ Correct Answer: 1

For a transmission line, if the reflection coefficient is 0.4, then the transmission coefficient is:

1. 0.4
2. 1.4
3. 0.8
4. 2.8

✅ Correct Answer: 2

If the transmission coefficient of a transmission line is 1.6, then the reflection co efficient is:

1. 0.8
2. 0.6
3. 0.4
4. 0.3

✅ Correct Answer: 2

For a transmission line, if the transmission coefficient is 1.4, then the insertion loss in dB is:

1. -2.922dB
2. 29dB
3. 1.46dB
4. -29dB

✅ Correct Answer: 1

The relation between nepers and decibels is:

1. 1 Np= 8.686 dB
2. 1 dB=8.868 dB
3. Np≥dB
4. dB≥Np

✅ Correct Answer: 1

Smith chart is based on the polar plot of:

1. Reactance
2. Voltage
3. Current
4. Voltage reflection co-efficient

✅ Correct Answer: 4

Any passively realizable reflection coefficient can be plotted as a unique point on the smith chart. This statement implies that:

1. Reflection co-efficient less than or equal to 1 can be plotted
2. Reflection co-efficient greater than or equal to 1 can be plotted
3. Transmission co-efficient has to be less than or equal to one for the point to be located
4. T=Г+1

✅ Correct Answer: 1

If the characteristic impedance of a ƛ/2 transmission line is 50 Ω and reflection coefficient 0.3, then its input impedance

1. 26.92 Ω
2. 30 Ω
3. 40 Ω
4. 34.87 Ω

✅ Correct Answer: 1

If the normalized input impedance of a transmission line is 0.5 Ω, then he reflection coefficient of a ƛ/2 transmission line is

1. 0.3334
2. 0.5
3. 0.6667
4. 1

✅ Correct Answer: 1

If the input impedance of a ƛ/2 transmission line is 100 Ω with a voltage reflection coefficient of 0.344, then the characteristic impedance of the transmission line is:

1. 200 Ω
2. 100 Ω
3. 50 Ω
4. None of the mentioned

✅ Correct Answer: 1

Normalized impedance of 0.3+j0.4 lies in the:

1. Upper half of the impedance smith chart
2. Lower half of the impedance smith chart
3. Horizontal line of the chart
4. None of the mentioned

✅ Correct Answer: 1

Normalized impedance of 1-j is:

1. In the upper half of the impedance smith chart
2. In the Lower half of the impedance smith chart
3. On the outer most circle of the smith chart.
4. On the horizontal line of the smith chart

✅ Correct Answer: 2

If a transmission line of a characteristic impedance 100 Ω is terminated with a load impedance of 300+j200 Ω, then the normalized load impedance is:

1. 1+j
2. 1-j
3. 3+2j
4. 2-3j

✅ Correct Answer: 3

If the normalized load impedance of a transmission line is 0.3-j0.4 with a characteristic impedance of 50 Ω, then the load impedance is:

1. 15-j20
2. 15+j20
3. 1-j
4. 0.3-0.4j

✅ Correct Answer: 1

To get an admittance chart from an impedance chart:

1. Smith chart has to be rotated by 90⁰
2. Smith chart has to be rotated by 180⁰
3. Admittance chart cannot be obtained from the impedance chart anyway.
4. None of the mentioned

✅ Correct Answer: 2

If a transmission line of characteristic impedance 50 Ω is to be matched to a load of 100Ω, then the characteristic impedance of the ƛ/4 transmission line to be used is:

1. 70.71 Ω
2. 50 Ω
3. 100 Ω
4. 75 Ω

✅ Correct Answer: 1

If a λ/4 transmission line is 100Ω is used to match a transmission line to a load of 100Ω, then the characteristic impedance of the transmission line is:

1. 100 Ω
2. 50 Ω
3. 70.71 Ω
4. 200 Ω

✅ Correct Answer: 1

If there is no standing wave on a transmission line, then the value of SWR is:

1. 1
2. 0
3. Infinity
4. Insufficient data

✅ Correct Answer: 1

When a λ/4 transmission line is used for impedance matching, then which of the following is valid?

1. Standing waves are present on the λ/4 transmission line
2. No standing waves on the λ/4 transmission line
3. Standing waves are not present both on the feed line and the matching λ/4 line
4. Standing waves are present on both the feed line and the matching λ/4 line

✅ Correct Answer: 1

For a transmission line , if the input impedance of the transmission line is 100Ω with a characteristic impedance of 150Ω, then the magnitude of the reflection co efficient:

1. 0.5
2. 1
3. 0.2
4. 0

✅ Correct Answer: 3

If the reflection co-efficient of a transmission line is 0.334 with a characteristic impedance of 50Ω then the input impedance of the transmission line is:

1. 100 Ω
2. 50 Ω
3. 150 Ω
4. None of the mentioned

✅ Correct Answer: 1

The value of reflection co efficient when a transmission line is matched to the load is:

1. 1
2. 0
3. 0.707
4. cannot be determined

✅ Correct Answer: 2

The value of transmission co efficient when a transmission line is matched to a load is:

1. 1
2. 0
3. 0.5
4. 0.707

✅ Correct Answer: 1