R4RIN – MCQs, Mock Tests | Electrical engineering Microwave Engineering MCQs Set-8

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

✅ Correct Answer: 1

_________ has a constant power spectral density.

1. White noise
2. Gaussian noise
3. Thermal noise
4. Shot noise

✅ Correct Answer: 1

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

✅ Correct Answer: 1

Antennas are bidirectional devices.

1. True
2. False
3.
4.

✅ Correct Answer: 1

Dipole antennas are an example for:

1. Wire antennas
2. Aperture antennas
3. Array antennas
4. None of the mentioned

✅ Correct Answer: 1

_________ 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

✅ Correct Answer: 2

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

✅ Correct Answer: 4

________ 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

✅ Correct Answer: 1

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

✅ Correct Answer: 2

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

✅ Correct Answer: 2

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

✅ Correct Answer: 3

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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

1. Simplex
2. Duplex
3. Half duplex
4. None of the mentioned

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

✅ Correct Answer: 3

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

✅ Correct Answer: 4

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

1. true
2. false
3.
4.

✅ Correct Answer: 1

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

1. true
2. false
3.
4.

✅ Correct Answer: 1

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

1. true
2. false
3.
4.

✅ Correct Answer: 2

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

1. 12
2. 24
3. 36
4. 48

✅ Correct Answer: 2

GPS operates at a single frequency band.

1. true
2. false
3.
4.

✅ Correct Answer: 2

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

1. true
2. false
3.
4.

✅ Correct Answer: 2

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

1. true
2. false
3.
4.

✅ Correct Answer: 2

Bluetooth devices operate at a frequency of :

1. 2.4 GHz
2. 4.5 GHz
3. 5.7 GHz
4. none of the mentioned

✅ Correct Answer: 1

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

1. ASK
2. BPSK
3. QAM
4. QPSK

✅ Correct Answer: 3

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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

✅ Correct Answer: 2

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

✅ Correct Answer: 2

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

✅ Correct Answer: 2

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

✅ Correct Answer: 4

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

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

✅ Correct Answer: 1

__________ 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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

✅ Correct Answer: 3

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

✅ Correct Answer: 3

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

1. RF amplifier
2. Local oscillator
3. IF filter
4. IF amplifier

✅ Correct Answer: 3

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
3.
4.

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

1. Antenna
2. Electron gun
3. Photon amplifier
4. Microwave tube

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

1. Three
2. Four
3. Two
4. Five

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

✅ Correct Answer: 1

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

1. Two
2. Four
3. Three
4. One

✅ Correct Answer: 1

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

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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

✅ Correct Answer: 2

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

1. True
2. False
3.
4.

✅ Correct Answer: 2

_______ 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

✅ Correct Answer: 1

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

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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
3.
4.

✅ Correct Answer: 1

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

✅ Correct Answer: 4

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

1. Strip line
2. Microstrip lines
3. Coaxial cables
4. Rectangular waveguide

✅ Correct Answer: 2

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

✅ Correct Answer: 2

______ 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

✅ Correct Answer: 2

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

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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

✅ Correct Answer: 2

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

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 1

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

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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
3.
4.

✅ Correct Answer: 1

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

1. true
2. false
3.
4.

✅ Correct Answer: 2

The current gain of a BJT ________ with frequency.

1. increases
2. decreases
3. remains constant
4. none of the mentioned

✅ Correct Answer: 1

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

✅ Correct Answer: 3

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

1. true
2. false
3.
4.

✅ Correct Answer: 2

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

✅ Correct Answer: 2

_____ 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

✅ Correct Answer: 1

Reciprocal phase shifters give different phase shift in different direction.

1. True
2. False
3.
4.

✅ Correct Answer: 2

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

✅ Correct Answer: 1

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
3.
4.

✅ Correct Answer: 1

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

1. True
2. False
3.
4.

✅ Correct Answer: 1