R4RIN – MCQs, Mock Tests | Electrical engineering Microwave Engineering MCQs Set-6

Advantage of chebyshev matching transformers over binomial transformers is:

1. higher gain
2. low power losses
3. higher roll-off in the characteristic curve
4. higher bandwidth

✅ Correct Answer: 4

There are passband ripples present in the chebyshev characteristic curve.

1. true
2. false
3.
4.

✅ Correct Answer: 1

Chebyshev matching transformers can be universally used for impedance matching in any of the microwave networks.

1. true
2. false
3.
4.

✅ Correct Answer: 2

Chebyshev polynomials do not obey the equal-ripple property.

1. true
2. false
3.
4.

✅ Correct Answer: 2

For values of x greater than 1, the chebyshev polynomial in its trigonometric form cannot be determined.

1. true
2. false
3.
4.

✅ Correct Answer: 2

A single section tapered line is more efficient in impedance matching than a multisection tapered line for impedance matching.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Passband characteristics of tapered lines differ from one type of taper to another.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The value of constant ‘a’ for an exponentially tapered line of length 5 cm with load impedance being 100Ω and characteristic impedance of the line is 50Ω is:

1. 0.1386
2. 0.265
3. 0.5
4. 0.2

✅ Correct Answer: 1

Reflection co-efficient magnitude response is an exponential curve for tapered line.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Triangular taper is the best solution for any impedance matching requirement.

1. True
2. False
3.
4.

✅ Correct Answer: 2

For any load impedance, perfect match can be obtained and the minimum reflection co-efficient achieved can be zero.

1. True
2. False
3.
4.

✅ Correct Answer: 2

For a given load (a fixed RC product), a broader bandwidth can be achieved with a low reflection co-efficient in the passband.

1. True
2. False
3.
4.

✅ Correct Answer: 2

A perfect match can be obtained in the passband for any impedance matching circuit around the center frequency for which it is defined.

1. True
2. False
3.
4.

✅ Correct Answer: 2

In a series LCR circuit, at resonance point the energy stored in the inductor and capacitor in the form of magnetic and electric energies are equal.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Quality factor-Q of a resonant circuit signifies:

1. Loss in the resonant circuit
2. Gain in the resonant circuit
3. Magnetic energy stored in the circuit
4. Electric energy stored in the circuit

✅ Correct Answer: 1

The total energy stored in a series RLC circuit is equal to the energy stored in the inductor.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Higher the quality factor of a series LCR circuit, greater is the operating bandwidth of the resonant circuit.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The plot of input impedance magnitude v/s frequency has a peak at the resonant frequency.

1. True
2. False
3.
4.

✅ Correct Answer: 2

For a parallel resonance circuit, the plot of input impedance magnitude v/s frequency has a dip at the resonant frequency.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The relation between unloaded Q and external Q is:

1. External Q> unloaded Q
2. Unloaded Q> external Q
3. External Q = unloaded Q
4. None of the mentioned

✅ Correct Answer: 2

Loaded Q and External Q are 2 different parameters.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The bandwidth of a series RLC circuit is 200 Hz. Then the quality factor of the circuit is:

1. 200
2. 100
3. 0.005
4. 0.5

✅ Correct Answer: 3

If a parallel RLC circuit is excited with a source of 8v, 50 Hz and the circuit has an inductor of 1mH, capacitor of 1µF and a resistor of 50Ω, then the power loss that occurs in the circuit is:

1. 6.4mW
2. 3.2mW
3. 12.8mV
4. None of the mentioned

✅ Correct Answer: 1

Lumped elements can be used to make resonators that rare to be operated at microwave frequencies.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Quality factor of a coaxial cable transmission line is independent of the medium between the wires of the transmission line.

1. True
2. False
3.
4.

✅ Correct Answer: 2

An air coaxial cable has attenuation of 0.022 and phase constant of 104.7, then the quality factor of a λ/2 short circuited resonator made out of this material is:

1. 2380
2. 1218
3. 1416
4. Insufficient data

✅ Correct Answer: 1

The equivalent resistance of a short circuited λ/4 transmission line is independent of the characteristic impedance of the transmission line.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The equivalent capacitance of a short circuited λ/4 transmission line is dependent on the characteristic impedance of the transmission line.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Inductance of an open circuited λ/2 transmission line is dependent on the characteristic impedance of the transmission line.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Microwave resonators can be constructed from open sections of waveguide.

1. True
2. False
3.
4.

✅ Correct Answer: 2

There is no energy stored inside a rectangular waveguide cavity resonator.

1. True
2. False
3.
4.

✅ Correct Answer: 2

A dielectric resonator is considered to be closed at both the ends.

1. true
2. false
3.
4.

✅ Correct Answer: 2

A dielectric material in the form of a small cube or disc can be used as a resonator.

1. true
2. false
3.
4.

✅ Correct Answer: 1

The level of coupling required between a resonator and its attached circuitry is a standard and independent of the application where coupling is required.

1. true
2. false
3.
4.

✅ Correct Answer: 2

A measure of the level of coupling between a resonator and a feed is given by:

1. coupling coefficient
2. power transfer coefficient
3. voltage coefficient
4. reflection coefficient

✅ Correct Answer: 1

To obtain maximum power transfer between a resonator and feed line, the resonator should be matched to the load at:

1. resonant frequency
2. cutoff frequency
3. zero frequency
4. none of the mentioned

✅ Correct Answer: 1

Coupling coefficient Q can be defined as the ratio of unloaded Q to external Q.

1. true
2. false
3.
4.

✅ Correct Answer: 1

When the coupling coefficient is lesser than one, the resonator is over coupled to the feed line.

1. true
2. false
3.
4.

✅ Correct Answer: 2

Direct measurement of the unloaded Q of a resonator is not possible.

1. true
2. false
3.
4.

✅ Correct Answer: 1

For practical applications cavity resonators can be modified as per the requirement of the application where it is used.

1. true
2. false
3.
4.

✅ Correct Answer: 1

When coupling coefficient is 1, the resonator is ________ to the feed line.

1. under coupled
2. over coupled
3. critically coupled
4. none of the mentioned

✅ Correct Answer: 3

In aperture coupling, a small aperture in the transverse wall of the waveguide acts as:

1. shunt inductance
2. shunt capacitance
3. series inductance
4. series capacitance

✅ Correct Answer: 1

One of the most commonly used dielectric materials is:

1. barium tetratetanate
2. titanium
3. teflon
4. none of the mentioned

✅ Correct Answer: 1

Dielectric resonators use materials that are less lossy.

1. true
2. false
3.
4.

✅ Correct Answer: 1

The resonant frequency of a dielectric resonator cannot be mechanically tuned.

1. true
2. false
3.
4.

✅ Correct Answer: 1

Q factor does not exist for dielectric resonator.

1. true
2. false
3.
4.

✅ Correct Answer: 2

The direction of propagation is in z direction outside the dielectric in the resonator.

1. true
2. false
3.
4.

✅ Correct Answer: 2

A T junction has a 3×3 ‘s’ matrix.

1. True
2. False
3.
4.

✅ Correct Answer: 1

If all the ports of a microwave network are matched, then the diagonal elements of the S matrix of the network is zero.

1. True
2. False
3.
4.

✅ Correct Answer: 1

A lossless reciprocal 3 port network can be matched at all the three ports.

1. True
2. False
3.
4.

✅ Correct Answer: 2

A circulator is a 3 port network that allows energy flow in clockwise direction only.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The diagonal elements of the S matrix of an improperly matched circulator is zero.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Coupling factor of a directional coupler must be maximum and is a key factor that determines the performance of the coupler.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Directivity of a directional coupler signifies the direction of power flow in the coupler.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Insertion loss is the power delivered to the through port.

1. True
2. False
3.
4.

✅ Correct Answer: 1

In a symmetric coupler, the power delivered to the through port and output port are equal.

1. True
2. False
3.
4.

✅ Correct Answer: 1

A T junction power divider can be used only for division of power.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The lossless T junction dividers can be can all be modeled as a junction of three transmission lines.

1. True
2. False
3.
4.

✅ Correct Answer: 1

For the realization of lossless T-junction power divider using transmission lines, the characteristic impedance of the transmission line has to be real.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Hybrid couplers are also a type of directional couplers.

1. True
2. False
3.
4.

✅ Correct Answer: 1

A lossy T junction can be matched at all the three ports.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The diagonal elements of the s matrix of a resistive T junction are:

1. 0
2. 1
3. 0.5
4. 1.5

✅ Correct Answer: 1

The power delivered to the input port of a resistive power divider is equal to the source voltage applied.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The power input at the port 1 of resistive T junction is equally divided among the 2 output ports of the T junction.

1. True
2. False
3.
4.

✅ Correct Answer: 2

S12 curve of a Wilkinson coupler when plotted versus frequency is a line passing through origin.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The plot of S23 v/s frequency has the same curve as that of S11 v/s frequency.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The plot of frequency v/s S11 parameter of a Wilkinson coupler has a dip at the frequency at which it is designed to operate.

1. True
2. False
3.
4.

✅ Correct Answer: 1

A Wilkinson coupler designed can be operated at any frequency.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Wilkinson power divider is an equal split power divider.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Branch-line couplers are also popular as Quadrature hybrids.

1. True
2. False
3.
4.

✅ Correct Answer: 1

A branch-line coupler is an asymmetric coupler.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The plot S11 v/s frequency for a branch-line coupler has a straight line characteristic for a wide range of frequency around the designed frequency range.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The curve of S14 for a branch-line coupler is similar to that of the S11 curve of the branch-line coupler.

1. True
2. False
3.
4.

✅ Correct Answer: 1

S12 and S13 curves for branch-line couplers are almost a straight line parallel to X –axis. Both the curves are similar and follow same path.

1. True
2. False
3.
4.

✅ Correct Answer: 1

If the branch-line impedance of a coupler designed to operate at 1 GHz is 70.70 Ω, then the characteristic impedance of the material of the arms of the branch-line coupler is:

1. 70.7 Ω
2. 50 Ω
3. 100 Ω
4. None of the mentioned

✅ Correct Answer: 3

In coupled line directional couplers, power from one line to another is transmitted through a microstrip line running between them.

1. true
2. false
3.
4.

✅ Correct Answer: 2

The number of conductors used in the construction of coupled line couplers is fixed.

1. true
2. false
3.
4.

✅ Correct Answer: 2

1800 hybrid is a network in which there is a phase shift of 1800 between the input signal applied and the output taken.

1. true
2. false
3.
4.

✅ Correct Answer: 2

Port 1 and port 4 of 1800 hybrid are called sum and difference ports respectively because of their behavior and action mechanism.

1. true
2. false
3.
4.

✅ Correct Answer: 1

S matrix of 1800 hybrid consists of all diagonal elements zero.

1. true
2. false
3.
4.

✅ Correct Answer: 1

In 1800 hybrid, different power levels can be received at the two output ports of the hybrid.

1. true
2. false
3.
4.

✅ Correct Answer: 2

In a waveguide magic-T there is no coupling of power between port 1 and port 4.

1. true
2. false
3.
4.

✅ Correct Answer: 1

The tapered coupled line 1800 hybrid can provide an arbitrary power division at the 2 output ports of the coupler.

1. true
2. false
3.
4.

✅ Correct Answer: 1

Moreno crossed-guide coupler is a waveguide directional coupler consists of four waveguides at right angle.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Ribblet short-slot coupler consists of two waveguides that are separated by a distance “d”.

1. True
2. False
3.
4.

✅ Correct Answer: 2

Symmetric tapered coupled line couplers offer higher bandwidth when compared to other forms of couplers.

1. True
2. False
3.
4.

✅ Correct Answer: 1

The coupling and directivity of couplers with apertures in planar lines can be adjusted as per the requirement of the application.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Reflectometer can also be used as a frequency meter.

1. True
2. False
3.
4.

✅ Correct Answer: 1

A basic Reflectometer circuit can be used to measure the _____________ magnitude of the unknown load.

1. Reflection coefficient
2. Standing wave ratio
3. Transmission coefficient
4. None of the mentioned

✅ Correct Answer: 1

________ is a three-port microwave device that can be lossless and matched at all spots.

1. Hybrid junction
2. Magic Tee
3. Circulator
4. Isolator

✅ Correct Answer: 3

There exists no difference between the construction of GaAs MESFET and silicon MOSFET except for the material used in their construction.

1. True
2. False
3.
4.

✅ Correct Answer: 2

MOSFETs can provide a power of several hundred watts when the devices are packaged in:

1. Series
2. Parallel
3. Diagonal
4. None of the mentioned

✅ Correct Answer: 2

High electron mobility transistors can be constructed with the use of single semiconductor material like GaAs that have high electron mobility.

1. True
2. False
3.
4.

✅ Correct Answer: 2

The curve of IDS v/s VDS of an FET does not vary with the gate to source voltage applied.

1. True
2. False
3.
4.

✅ Correct Answer: 2

High-power circuits generally use higher values of:

1. Gate to source current
2. Drain to source current
3. Drain current
4. Gate to source voltage

✅ Correct Answer: 3

High drain current at RF levels is achieved with the biasing and decoupling circuitry for a dual polarity supply.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Since multiple layers of semiconductor materials is used in high electron mobility transistors, this results in:

1. High gain
2. Power loss
3. Temperature sensitivity
4. Thermal stress

✅ Correct Answer: 4

A major disadvantage of high electron mobility transistor is that:

1. They have low gain
2. High manufacturing cost
3. Temperature sensitive
4. High driving voltage is required

✅ Correct Answer: 2

HEMT fabricated using GaN and aluminum gallium nitride on a silicon substrate can be used in :

1. High power transmitters
2. High power receivers
3. RADAR
4. Smart antennas

✅ Correct Answer: 1

The scattering parameter S11 for GaN HELMT increases with increase in frequency of operation

1. True
2. False
3.
4.

✅ Correct Answer: 2