Electrical engineering/Microwave Engineering MCQs Set-8 Sample Test,Sample questions

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Question: 
 If a ferrite slab produces a phase shift of 0.836 rad/ cm, then the length of the slab required to produce a phase shift of 135⁰ is:

1.2.81 cm

2.3 cm

3.2 cm

4.3.4 cm

Question: 
 Power radiated from an antenna per unit solid angle is called radiation intensity.

1.True

2.False

Question: 
A Dicke radiometer is identical to the total power radiometer in all aspects except that they have different receiving antenna.

1.True

2. False

Question: 
A gyrator can be made a passive device by certain design methods so that they do not affect the power levels of the circuit in which they are used.

1.True

2.False

Question: 
A major challenge in designing a radiometer is:

1.Design complexity

2.High cost

3.Requirement of highly sensitive receivers

4.None of the mentioned

Question: 
A parabolic reflector used for reception with the direct broadcast system is 18 inches in diameter and operates at 12.4 GHz. The far-field distance for this antenna is:

1.18 m

2. 13 m

3.16.4 m

4.17.3 m

Question: 
A radio receiver operating at microwave frequencies must have very high selectivity.

1.True

2.False

Question: 
A receiver system is operating at a bandwidth of 1 MHz and has a total system noise temperature of 762 K. then the output noise power is:

1.-110 dBm

2.-234 dBm

3. -145 dBm

4.-124 dBm

Question: 
A source has a cosine power pattern that is bidirectional. Given that the directivity of a unidirectional source with cosine power pattern has a directivity of 4, then the directivity of the unidirectional source is:

1.1

2.2

3.4

4.8

Question: 
A source has a sine squared radiation intensity power pattern. The directivity of the given source is:

1.1.5

2.3

3.2.5

4.3.5

Question: 
A typical radiometer would measure the brightness temperature over the range of about:

1.50-300 K

2.100-200 K

3.400-500 K

4.None of the mentioned

Question: 
A ________ determines the target range by measuring the round trip time of a pulsed microwave signal.

1.Pulse radar

2.Doppler radar

3.Cross section radar

4.None of the mentioned

Question: 
A __________ is a device that converts a guided electromagnetic wave on a transmission line into a plane wave propagating in free space.

1.Transmitting antenna

2.Receiving antenna

3.Radar

4.Mixer

Question: 
According to Planck’s radiation law, a body can radiate energy to the medium surrounding it under all conditions invariably.

1.True

2.False

Question: 
Advantage of HJT over BJT is that it has:

1.higher gain

2.high frequency of operation

3.sophisticated construction

4.none of the mentioned

Question: 
All modern wireless communication systems rely on digital modulation methods due to:

1.superior performance

2.low power requirements

3.sustainability

4. all of the mentioned

Question: 
An antenna source that radiates energy uniformly in all the directions is called:

1.Isotropic source

2.Anisotropic source

3.Point source

4. None of the mentioned

Question: 
Antenna noise temperature of a system is 210 K, noise temperature of transmission line is 123 K, loss of a transmission line connecting the antenna to receiver is 1.41 and noise temperature of the receiver cascade is 304 K. then the total system noise temperature is:

1.840 K

2.762 K

3.678 K

4. 1236 K

Question: 
Antenna that does not belong to the horn antenna family among the following are:

1.Pyramidal horn

2.Conical horn

3.bi-conical horn

4.None of the mentioned

Question: 
Antennas are bidirectional devices.

1.True

2.False

Question: 
Antennas having a constant pattern in the azimuthal plane are called _____________

1.High gain antenna

2.Omni directional antenna

3.Unidirectional antenna

4.Low gain antenna

Question: 
Antennas that radiate energy only in a specified are called anisotropic antennas.

1.True

2. False

Question: 
As the beam area of an antenna decreases, the directivity of the antenna:

1.Increases

2.Decreases

3.Remains unchanged

4.Depends on the type of the antenna

Question: 
Based on the size of the loops, loop antennas are classified as small and large loops. This is the only classification of loop antenna.

1.True

2.False

Question: 
Beamwidth and directivity are both measures of the focusing ability of an antenna.

1.True

2.False

Question: 
Bluetooth devices operate at a frequency of :

1.2.4 GHz

2.4.5 GHz

3.5.7 GHz

4.none of the mentioned

Question: 
Construction of pulse radar is much simpler than a Doppler radar.

1.True

2.False

Question: 
Dipole antennas are an example for:

1.Wire antennas

2. Aperture antennas

3.Array antennas

4.None of the mentioned

Question: 
Effective aperture is a parameter of the antenna that gives the physical aperture of the antenna.

1.True

2.False

Question: 
Ferrite phase shifters have more advantages over FETs and diodes in using them in microwave integrated circuits.

1.True

2. False

Question: 
For applications like missile fire control, bistatic radars are used.

1.True

2.False

Question: 
For radar system, antennas with a large beam width are preferred over narrow beam antennas.

1.True

2.False

Question: 
Given that the antenna efficiency is 0.9, equivalent brightness temperature is 200 K; physical temperature is 300 K, noise temperature of an antenna is:

1.220 K

2.210 K

3. 240 K

4.None of the mentioned

Question: 
Global positioning system uses _____ satellites in medium earth orbits to provide accurate position information.

1.12

2.24

3. 36

4.48

Question: 
GPS operates at a single frequency band.

1.true

2.false

Question: 
Hetero junction bipolar transistors have the same working principle and operation as that of a BJT.

1.true

2.false

Question: 
High directivity required in RADAR communication is satisfied using this type of antennas:

1.Wide band antennas

2.Antenna arrays

3.Slot antennas

4.Patch antennas

Question: 
Ideally, the number of point sources an antenna can resolve is numerically equal to:

1.Gain of the antenna

2.Directivity

3.Beam efficiency

4.Beam area

Question: 
If a receiver is operating at a bandwidth of 1 MHz and has antenna noise temperature of 210 K, then the input noise power is:

1.-90 dBm

2.-115 dBm

3.-56 dBm

4.-120 dBm

Question: 
If a transistor has a short circuit current gain of 25 and the capacitance measured in the hybrid-π model of the transistor was 60 pF. Then the threshold frequency of operation of the transistor is:

1.60 MHz

2.45.6 GHz

3.66.3 GHz

4. 34.8 GHz

Question: 
If an antenna radiates over half a sphere, directivity of the antenna is:

1.Two

2.Four

3.Three

4. One

Question: 
If the beam width of an antenna in two orthogonal planes are 300 and 600. Then the directivity of the antenna is:

1.24

2.18

3.36

4.12

Question: 
If the distance between a transmitting station and receiving station is 1 Km and if the antennas are operating at a wavelength of 5 cm, then the path loss is:

1.108 dB

2.12 dB

3. 45 dB

4.48 dB

Question: 
If the power input to an antenna is 100 mW and if the radiated power is measured to be 90 mW, then the efficiency of the antenna is:

1.75 %

2.80 %

3. 90 %

4.Insufficient data

Question: 
If the received power at antenna terminals is -80dBm, and if the input noise power is -115 dBm, then the input SNR is:

1.45 dB

2.-195 dB

3.-35 dB

4.35 dB

Question: 
If the received power at the antenna terminals is Si=-80 dBm and the output noise power is -110 dBm then the output signal to noise ratio is given by:

1.30 dB

2.-30 dB

3.35 dB

4.-35 dB

Question: 
In a RADAR system the transmitter of the radar is more sensitive than the receiver.

1.True

2.False

Question: 
In a receiver, if the noise figure of the mixer stage in the receiver is 7 dB, then the equivalent noise temperature is given that the receiver is operating at 290 K:

1.1163 K

2. 1789 K

3.1000 K

4.1234 K

Question: 
In military applications the radar cross sections of vehicles is minimized.

1.True

2.False

Question: 
In this method of wireless communication, communication happens only in one direction:

1.Simplex

2.Duplex

3.Half duplex

4.None of the mentioned

Question: 
Lens antennas are classified into two types. One being fast antenna, the other one is:

1.Slow antenna

2.Delay antenna

3.Dynamic antenna

4.None of the mentioned

Question: 
Link margin that is used to account for fading effects is called fade margin.

1.True

2.False

Question: 
Low is the G/T ratio of an antenna, higher is its efficiency.

1.True

2.False

Question: 
Most of the wireless systems today operate at a frequency of about:

1.800 MHz

2.100 MHz

3.80 MHz

4.None of the mentioned

Question: 
One of the most important requirements of a radio receiver is high gain.

1.True

2.False

Question: 
Patch antennas are the antennas of small size and are made of:

1.Strip line

2.Microstrip lines

3.Coaxial cables

4.Rectangular waveguide

Question: 
Point to point communication systems use low gain antennas for communication.

1.True

2.False

Question: 
Probability of bit error is greater for ASK as compared to FSK.

1.true

2.false

Question: 
Probability of bit error rate is greater for QPSK as compared to FSK.

1.true

2.false

Question: 
Pulse radar operating at 10GHz frequency has an antenna with a gain of 28 dB and a transmitted power of 2kW. If it is desired to detect a target of cross section 12m2, and the minimum detectable signal is -90 dBm, the maximum range of the radar is:

1.8114 m

2.2348 m

3.1256 m

4.4563 m

Question: 
Radiometry is a technique or the principle on which radar works.

1.True

2.False

Question: 
Reciprocal phase shifters give different phase shift in different direction.

1.True

2.False

Question: 
Reflector antennas are widely used to modify radiation patterns of radiating elements.

1.True

2.False

Question: 
The amount of power by which the received power must be greater than the threshold level required to maintain a minimum quality of service is called _______

1.Line loss

2.Link budget

3.Link margin

4.None of the mentioned

Question: 
The antenna in which location of the feed determines the direction of the lobe are:

1.Wire antenna

2.Loop antenna

3.Helical antenna

4. Horn antenna

Question: 
The antennas which offer high operational bandwidth and the antenna parameters are maintained over a wide range of antennas are called:

1.Wide band antennas

2.Array antennas

3.Parabolic antennas

4.None of the mentioned

Question: 
The basic equation of radiation that is applied to any antenna irrespective of the type of the antenna is:

1.iL= Qv

2.iQ = Lv

3.i/L=Q/v

4.None of the mentioned

Question: 
The basic requirements of transmitting antennas are:

1.High efficiency

2.Low side lobes

3.Large signal to noise ratio

4.Lone of the mentioned

Question: 
The beam width of the antenna pattern measured at half power points is called:

1.Half power beam width

2.Full null beam width

3.Beam width

4. None of the mentioned

Question: 
The current gain of a BJT ________ with frequency.

1.increases

2.decreases

3.remains constant

4.none of the mentioned

Question: 
The dominant factor affecting the accuracy of the total power radiometer is the variation of ___________

1.Gain in the overall system

2.The feedback circuit

3.Efficiency of the system

4.None of the mentioned

Question: 
The half power beam width of an antenna in both θ and φ are 400 each. Then the gain of the antenna is:

1.23

2.25

3.14

4.27

Question: 
The hybrid-π model of a BJT is useful for analysis at all frequency ranges and variation of other transistor parameters.

1.true

2.false

Question: 
The integrator circuit after the detector in the receiver circuit is used to smooth out the short term variations in the signal power.

1.True

2.False

Question: 
The members of the antenna family which are made of wires of certain value in terms of operating wavelength are called:

1.Loop antennas

2.Wire antennas

3.Dipole antenna

4.Slot antennas

Question: 
The modulation technique in which both amplitude and phase of the carrier are varied simultaneously is:

1.ASK

2.BPSK

3.QAM

4.QPSK

Question: 
The noise power will determine the maximum detectable signal level for a receiver.

1.True

2.False

Question: 
The noise temperature of an antenna is given by the expression:

1.radTb + (1-rad) Tp

2.(1-rad) TP

3.radTb

4.None of the mentioned

Question: 
The number N of radio transmitters or point sources of radiation distributed uniformly over the sky which an antenna can resolve is given by:

1.4π/ ΩA

2.2π/ ΩA

3.π/ ΩA

4.None of the mentioned

Question: 
The number of patterns radiation pattern required to specify the characteristic are :

1.Three

2.Four

3.Two

4.Five

Question: 
The output collector to emitter current of a BJT amplifier is independent of the input base current of the amplifier.

1.true

2.false

Question: 
The pattern of the reflector in a reflector antenna is called:

1.Primary pattern

2.Secondary pattern

3.Reflector pattern

4.None of the mentioned

Question: 
The probability of error depends on the ratio of bit energy to noise power density.

1.true

2.false

Question: 
The radar in which both transmission and reception is done using the same antenna are called:

1.Monostatic radar

2.Bistatic radar

3.Monopole radar

4.Dipole radar

Question: 
The receiver model of a total power radiometer is based on the:

1.AM receiver

2. FM receiver

3.Super heterodyne receiver

4.None of the mentioned

Question: 
The solid area through which all the power radiated by the antenna is:

1.Beam area

2.Effective area

3.Aperture area

4.Beam efficiency

Question: 
The system bandwidth of a total power radiometer is determined by the:

1.RF amplifier

2. Local oscillator

3. IF filter

4.IF amplifier

Question: 
The term radar cross section defines the:

1.Scattering ability of the target

2.Power radiating ability of the radar

3.Amount of energy scattered by unwanted objects

4.Cross section of radar area through which energy is emitted

Question: 
The terminal impedance of a dipole antenna is 710 Ω. The terminal impedance of the slot antenna given the intrinsic impedance of air is 377 Ω is:

1.100 Ω

2. 50 Ω

3.25 Ω

4.None of the mentioned

Question: 
There is no standard to be formed by commercial WLAN products.

1.true

2.false

Question: 
When the separation between two lines that carry the TEM wave approaches λ the wave tends to be radiated.

1.True

2.False

Question: 
WLAN is used for providing connection between a host computer and satellite for communication.

1.true

2.false

Question: 
_____ is a device that produces a phase shift of a required amount of the input wave.

1.Phase shifter

2.Attenuator

3.Resonator

4. None of the mentioned

Question: 
______ antennas have gain less than reflector antennas but have more lenient tolerance on surfaces.

1.Helical antennas

2.Lens antennas

3.Array antennas

4.Slot antennas

Question: 
_______ of an antenna is defined as the ratio of the induced voltage to the incident electric field.

1.Effective height

2.Gain

3. Directivity

4.Loss

Question: 
________ of an antenna is a plot of the magnitude of the far field strength versus position around the antenna.

1.Radiation pattern

2.Directivity

3.Beam width

4.None of the mentioned

Question: 
_________ antennas consist of a regular arrangement of antenna elements with a feed network

1.Aperture antennas

2.Array antennas

3.Printed antennas

4.Wire antennas

Question: 
_________ has a constant power spectral density.

1.White noise

2.Gaussian noise

3.Thermal noise

4.Shot noise

Question: 
_________ is a device that converts electrons to photons or vice-versa.

1.Antenna

2.Electron gun

3.Photon amplifier

4.Microwave tube

Question: 
__________ system obtains information about a target by transmitting a signal and receiving the echo from the target.

1.Radar

2.Sonar

3.Radiometer

4.None of the mentioned

Posted on by R4R Team

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