R4RIN – MCQs, Mock Tests | Electrical engineering Microwave Engineering MCQs Set-5

If the characteristic impedance of a transmission line 50 Ω and reflection coefficient is 0.0126+j0.1996, then load impedance is:

1. 47.3+j19.7Ω
2. 4.7+j1.97Ω
3. 0.26+j0.16
4. data insufficient

✅ Correct Answer: 1

If the normalized load impedance of a transmission line is 2, then the reflection co-efficient is:

1. 0.33334
2. 1.33334
3. 0
4. 1

✅ Correct Answer: 1

The major advantage of single stub tuning over other impedance matching techniques is:

1. Lumped elements are avoided
2. It can be fabricated as a part of transmission line media
3. It involves two adjustable parameters
4. All of the mentioned

✅ Correct Answer: 4

Shunt stubs are preferred for:

1. Strip and microstrip lines
2. Coplanar waveguides
3. Circular waveguide
4. Circulators

✅ Correct Answer: 1

The two adjustable parameters in single stub matching are distance‘d’ from the load to the stub position, and _________

1. Susceptance or reactance provided by the stub
2. Length of the stub
3. Distance of the stub from the generator
4. None of the mentioned

✅ Correct Answer: 1

In shunt stub matching, the key parameter used for matching is:

1. Admittance of the line at a point
2. Admittance of the load
3. Impedance of the stub
4. Impedance of the load

✅ Correct Answer: 1

For series stub matching, the parameter used for matching is:

1. Impedance of the transmission line at a point
2. Voltage at a point on the transmission line
3. Admittance at a point on the transmission line
4. Admittance of the load

✅ Correct Answer: 1

For co-axial lines and waveguides, ________ is more preferred.

1. Open circuited stub
2. Short circuited stub
3. Slotted section
4. Co-axial lines cannot be impedance matched

✅ Correct Answer: 2

For a load impedance of ZL=60-j80. Design of 2 single-stub shunt tuning networks to match this load to a 50Ω line is to be done. What is the normalized admittance obtained so as to plot it on smith chart?

1. 1+j
2. 0.3+j0.4
3. 0.4+j0.3
4. 0.3-j0.4

✅ Correct Answer: 2

If the normalized admittance at a point on a transmission line to be matched is 1+j1.47. Then the normalized susceptance of the stub used for shunt stub matching is:

1. 1Ω
2. 1.47 Ω
3. -1.47 Ω
4. -1 Ω

✅ Correct Answer: 3

After impedance matching, if a graph is plot with frequency v/s reflection co-efficient of the transmission line is done, then at the frequency point for which the design is done, which of the following is true?

1. There is a peak at this point of the curve
2. There is a dip at this point of the curve
3. The curve is a straight line
4. Such a plot cannot be obtained

✅ Correct Answer: 2

In series stub matching, if the normalized impedance at a point on the transmission line to be matched is 1+j1.33. Then the reactance of the series stub used for matching is:

1. 1 Ω
2. -1.33 Ω
3. -1 Ω
4. 1.33 Ω

✅ Correct Answer: 2

If D=1.6 and B=2.8 for a 2 port network, then Y₁₁=?

1. 0.5714
2. 0.987
3. 0.786
4. 1.75

✅ Correct Answer: 1

The major disadvantage of single stub tuning is:

1. it requires a variable length of line between the load and the stub
2. it involves 2 variable parameters
3. complex calculation
4. none of the mentioned

✅ Correct Answer: 1

The major advantage of double stub tuning is:

1. it uses 2 tuning stubs in fixed positions
2. it involves 2 stubs
3. length of the stub is variable
4. none of the mentioned

✅ Correct Answer: 1

In a double stub tuner circuit, the load is of _______ length from the first stub.

1. fixed length
2. arbitrary length
3. depends on the load impedance to be matched
4. depends on the characteristic impedance of the transmission line

✅ Correct Answer: 1

Double stub tuners are fabricated in coaxial line are connected in shunt with the main co-axial line.

1. true
2. false
3.
4.

✅ Correct Answer: 1

Impedance matching with a double stub tuner using a smith chart yields 2 solutions.

1. true
2. false
3.
4.

✅ Correct Answer: 1

All load impedances can be matched to a transmission line using double stub matching.

1. true
2. false
3.
4.

✅ Correct Answer: 1

The simplest method of reducing the forbidden range of impedances is:

1. increase the distances between the stubs
2. reduce the distance between the stubs
3. increase the length of the stubs
4. reduce the length of the stubs

✅ Correct Answer: 2

Stub spacing that are near 0 and λ/2 lead to more frequency sensitive matching networks.

1. true
2. false
3.
4.

✅ Correct Answer: 1

The standard stub spacing usually used is:

1. 0, λ/2
2. λ/4, λ/8
3. λ/8, 3λ/8
4. none of the mentioned

✅ Correct Answer: 3

If the length of the line between the first stub and the load can be adjusted, the admittance can be moved from the forbidden region.

1. true
2. false
3.
4.

✅ Correct Answer: 1

A quarter wave transformer is useful for matching any load impedance to a transmission line.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Major advantage of a quarter wave transformer is:

1. It gives proper matching
2. It gives high gain
3. Broader bandwidth
4. None of the mentioned

✅ Correct Answer: 3

If a narrow band impedance match is required, then more multi section transformers must be used.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The major drawback of the quarter wave transformer that it cannot match complex load to a transmission line cannot be overcome.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Complex load impedance can be converted to real load impedance by:

1. Scaling down the load impedance
2. By introducing an approximate length of transmission line between load and quarter wave transformer
3. Changing the operating wavelength
4. None of the mentioned

✅ Correct Answer: 2

Converting complex load into real load for impedance matching has no effect on the bandwidth of the match.

1. True
2. False
3.
4.

✅ Correct Answer: 2

If a single section quarter wave transformer is used for impedance matching at some frequency, then the length of the matching line is:

1. Is different at different frequencies
2. Is a constant
3. Is λ/2 for other frequencies
4. None of the mentioned

✅ Correct Answer: 1

Quarter wave transformers cannot be used for non-TEM lines for impedance matching.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The reactances associated with the transmission line due to discontinuities:

1. Can be ignored
2. Have to matched
3. Discontinuities do not exist
4. None of the mentioned

✅ Correct Answer: 2

If a load of 10Ω has to be matched to a transmission line of characteristic impedance of 50Ω, then the characteristic impedance of the matching section of the transmission line is:

1. 50Ω
2. 10Ω
3. 22.36Ω
4. 100Ω

✅ Correct Answer: 3

Discontinuities in the matching quarter wave transformer are not of considerable amount and are negligible.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The overall reflection coefficient of a matching quarter wave transformer cannot be calculated because of physical constraints.

1. True
2. False
3.
4.

✅ Correct Answer: 2

In the multiple reflections analysis method, the total reflection is:

1. An infinite sum of partial reflections
2. An infinite sum of partial reflection and transmissions
3. Constant value
4. Finite sum of partial reflections

✅ Correct Answer: 2

If the first and the third reflection coefficients of a matched line is 0.2 and 0.01, then the total reflection coefficient if quarter wave transformer is used for impedance matching is:

1. 0.2
2. 0.01
3. 0.21
4. 0.19

✅ Correct Answer: 4

To compute the total reflection of a multi-section transmission line, the lengths of the transmission lines considered are all unequal.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The total approximate reflection coefficient is a finite sum of reflection co-efficient of individual matching section of the matching network.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Using the relation for total reflection co-efficient certain designs of matching networks can be made as per practical requirements.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The passband response of a binomial matching transformer can be called optimum:

1. if the roll off in the response curve is high
2. if the response is flat in the impedance matched region
3. if the matching network is frequency sensitive
4. none of the mentioned

✅ Correct Answer: 2

The passband response of a binomial matching transformer can be called optimum:

1. if the roll off in the response curve is high
2. if the response is flat in the impedance matched region
3. if the matching network is frequency sensitive
4. none of the mentioned

✅ Correct Answer: 2

If a quality binomial matching transformer gives a good flat response curve, it is called “maximally flat”.

1. true
2. false
3.
4.

✅ Correct Answer: 1

The response curve of a binomial matching transformer is plotted for each section of the matching network individually and then analyzed for optimum solution.

1. true
2. false
3.
4.

✅ Correct Answer: 2

To obtain a flat curve in the response of a binomial multisection transformer, N-1 derivatives of │Г (θ) │are set to zero. This implies:

1. the frequency sensitivity of the matching section is increased linearly
2. the frequency sensitivity of the matching section is increased exponentially
3. roll off in the curve is increased
4. none of the mentioned

✅ Correct Answer: 4

The condition │Г (θ) │=0 for θ=π/2 of a binomial multi section transformer corresponds to the:

1. upper cutoff frequency
2. lower cutoff frequency
3. center frequency
4. none of the mentioned

✅ Correct Answer: 3

In the plot of normalized frequency v/s reflection co-efficient for a binomial multisection filter, the curve has a dip at:

1. center frequency
2. upper cutoff frequency
3. lower cutoff frequency
4. none of the mentioned

✅ Correct Answer: 1

As the number of sections in the binomial multisection transformer increases the plot of normalized frequency v/s reflection co-efficient has a wider open curve.

1. true
2. false
3.
4.

✅ Correct Answer: 1

A three section binomial transformer is used to match a 100Ω transmission line to a 50Ω transmission line. Then the value of the constant ‘A’ for this design is:

1. -0.0433
2. 0.0433
3. 0.01
4. -0.01

✅ Correct Answer: 1

The major disadvantage of binomial multi section transformer is higher bandwidth cannot be achieved.

1. true
2. false
3.
4.

✅ Correct Answer: 1