Electrical engineering/Microwave Engineering MCQs Set-6 Sample Test,Sample questions

Question:
 Loaded Q and External Q are 2 different parameters.

1.True

2.False


Question:
 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


Question:
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


Question:
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


Question:
A branch-line coupler is an asymmetric coupler.

1.True

2.False


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

1.True

2. False


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

1.true

2.false


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

1.true

2.false


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

1.True

2.False


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

1.True

2.False


Question:
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


Question:
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


Question:
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


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

1.True

2.False


Question:
A T junction has a 3×3 ‘s’ matrix.

1.True

2.False


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

1.True

2.False


Question:
A Wilkinson coupler designed can be operated at any frequency.

1.True

2.False


Question:
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


Question:
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


Question:
Branch-line couplers are also popular as Quadrature hybrids.

1.True

2.False


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

1.true

2.false


Question:
Chebyshev polynomials do not obey the equal-ripple property.

1.true

2.false


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

1.true

2.false


Question:
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


Question:
Dielectric resonators use materials that are less lossy.

1.true

2.false


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

1.true

2.false


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

1.True

2.False


Question:
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


Question:
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


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

1.True

2.False


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

1.true

2.false


Question:
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


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

1.true

2.false


Question:
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


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

1.True

2.False


Question:
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


Question:
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


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

1.True

2.False


Question:
Hybrid couplers are also a type of directional couplers.

1.True

2.False


Question:
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


Question:
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


Question:
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


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

1.true

2.false


Question:
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


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

1.True

2.False


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

1.true

2.false


Question:
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


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

1.true

2.false


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

1.True

2.False


Question:
Insertion loss is the power delivered to the through port.

1.True

2.False


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

1.True

2. False


Question:
Microwave resonators can be constructed from open sections of waveguide.

1.True

2.False


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

1.True

2.False


Question:
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


Question:
One of the most commonly used dielectric materials is:

1.barium tetratetanate

2.titanium

3.teflon

4.none of the mentioned


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

1.True

2.False


Question:
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


Question:
Q factor does not exist for dielectric resonator.

1.true

2.false


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

1.True

2.False


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

1.True

2.False


Question:
Reflectometer can also be used as a frequency meter.

1.True

2.False


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

1.True

2.False


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

1.true

2.false


Question:
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


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

1.True

2.False


Question:
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


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

1.True

2.False


Question:
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


Question:
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


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

1.True

2.False


Question:
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


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

1.0

2.1

3.0.5

4.1.5


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

1.True

2.False


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

1.true

2.false


Question:
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


Question:
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


Question:
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


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

1.True

2.False


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

1.true

2.false


Question:
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


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

1.True

2.False


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

1.True

2.False


Question:
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


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

1.True

2.False


Question:
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


Question:
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


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

1.true

2.false


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

1.True

2.False


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

1.true

2.false


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

1.True

2.False


Question:
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


Question:
There are passband ripples present in the chebyshev characteristic curve.

1.true

2.false


Question:
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


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

1.True

2.False


Question:
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


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

1.True

2.False


Question:
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


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

1.true

2.false


Question:
Wilkinson power divider is an equal split power divider.

1.True

2.False


Question:
________ 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


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