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 135â° is:
1.2.81 cm
2.3 cm
3.2 cm
4.3.4 cm
Posted Date:-2022-06-02 07:27:16
Power radiated from an antenna per unit solid angle is called radiation intensity.
1.True
2.False
Posted Date:-2022-05-31 18:11:01
A Dicke radiometer is identical to the total power radiometer in all aspects except that they have different receiving antenna.
1.True
2. False
Posted Date:-2022-05-31 18:05:34
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
Posted Date:-2022-06-02 07:27:45
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
Posted Date:-2022-05-31 18:02:50
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
Posted Date:-2022-05-31 17:37:48
A radio receiver operating at microwave frequencies must have very high selectivity.
1.True
2.False
Posted Date:-2022-05-31 17:44:21
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
Posted Date:-2022-05-31 17:54:08
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
Posted Date:-2022-05-31 18:23:28
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
Posted Date:-2022-05-31 18:24:14
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
Posted Date:-2022-05-31 18:06:14
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
Posted Date:-2022-05-31 17:58:43
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
Posted Date:-2022-05-31 17:35:51
According to Planck’s radiation law, a body can radiate energy to the medium surrounding it under all conditions invariably.
1.True
2.False
Posted Date:-2022-05-31 18:02:16
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
Posted Date:-2022-06-02 07:23:31
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
Posted Date:-2022-05-31 17:45:05
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
Posted Date:-2022-05-31 18:22:35
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
Posted Date:-2022-05-31 17:53:00
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
Posted Date:-2022-05-31 18:17:25
Antennas are bidirectional devices.
1.True
2.False
Posted Date:-2022-05-31 17:36:09
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
Posted Date:-2022-05-31 17:38:59
Antennas that radiate energy only in a specified are called anisotropic antennas.
1.True
2. False
Posted Date:-2022-05-31 18:22:53
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
Posted Date:-2022-05-31 18:11:51
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
Posted Date:-2022-05-31 18:16:40
Beamwidth and directivity are both measures of the focusing ability of an antenna.
1.True
2.False
Posted Date:-2022-05-31 17:39:27
Bluetooth devices operate at a frequency of :
1.2.4 GHz
2.4.5 GHz
3.5.7 GHz
4.none of the mentioned
Posted Date:-2022-05-31 17:49:33
Construction of pulse radar is much simpler than a Doppler radar.
1.True
2.False
Posted Date:-2022-05-31 17:59:03
Dipole antennas are an example for:
1.Wire antennas
2. Aperture antennas
3.Array antennas
4.None of the mentioned
Posted Date:-2022-05-31 17:36:41
Effective aperture is a parameter of the antenna that gives the physical aperture of the antenna.
1.True
2.False
Posted Date:-2022-05-31 18:14:38
Ferrite phase shifters have more advantages over FETs and diodes in using them in microwave integrated circuits.
1.True
2. False
Posted Date:-2022-06-02 07:28:08
For applications like missile fire control, bistatic radars are used.
1.True
2.False
Posted Date:-2022-05-31 17:57:22
For radar system, antennas with a large beam width are preferred over narrow beam antennas.
1.True
2.False
Posted Date:-2022-05-31 17:56:32
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
Posted Date:-2022-05-31 17:51:49
Global positioning system uses _____ satellites in medium earth orbits to provide accurate position information.
1.12
2.24
3. 36
4.48
Posted Date:-2022-05-31 17:46:53
GPS operates at a single frequency band.
1.true
2.false
Posted Date:-2022-05-31 17:47:32
Hetero junction bipolar transistors have the same working principle and operation as that of a BJT.
1.true
2.false
Posted Date:-2022-06-02 07:22:57
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
Posted Date:-2022-05-31 18:21:09
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
Posted Date:-2022-05-31 18:14:14
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
Posted Date:-2022-05-31 17:52:26
If a transistor has a short circuit current gain of 25 and the capacitance measured in the hybrid-Ï€ 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
Posted Date:-2022-06-02 07:14:06
If an antenna radiates over half a sphere, directivity of the antenna is:
1.Two
2.Four
3.Three
4. One
Posted Date:-2022-05-31 18:12:21
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
Posted Date:-2022-05-31 17:39:59
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
Posted Date:-2022-05-31 17:42:43
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
Posted Date:-2022-05-31 17:40:34
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
Posted Date:-2022-05-31 17:53:34
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
Posted Date:-2022-05-31 17:55:00
In a RADAR system the transmitter of the radar is more sensitive than the receiver.
1.True
2.False
Posted Date:-2022-05-31 17:56:11
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
Posted Date:-2022-05-31 17:51:13
In military applications the radar cross sections of vehicles is minimized.
1.True
2.False
Posted Date:-2022-05-31 17:59:25
In this method of wireless communication, communication happens only in one direction:
1.Simplex
2.Duplex
3.Half duplex
4.None of the mentioned
Posted Date:-2022-05-31 17:42:03
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
Posted Date:-2022-05-31 18:20:00
Link margin that is used to account for fading effects is called fade margin.
1.True
2.False
Posted Date:-2022-05-31 17:43:39
Low is the G/T ratio of an antenna, higher is its efficiency.
1.True
2.False
Posted Date:-2022-05-31 17:33:29
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
Posted Date:-2022-05-31 17:41:13
One of the most important requirements of a radio receiver is high gain.
1.True
2.False
Posted Date:-2022-05-31 17:43:59
Patch antennas are the antennas of small size and are made of:
1.Strip line
2.Microstrip lines
3.Coaxial cables
4.Rectangular waveguide
Posted Date:-2022-05-31 18:17:55
Point to point communication systems use low gain antennas for communication.
1.True
2.False
Posted Date:-2022-05-31 17:41:33
Probability of bit error is greater for ASK as compared to FSK.
1.true
2.false
Posted Date:-2022-05-31 17:45:45
Probability of bit error rate is greater for QPSK as compared to FSK.
1.true
2.false
Posted Date:-2022-05-31 17:46:11
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
Posted Date:-2022-05-31 17:59:59
Radiometry is a technique or the principle on which radar works.
1.True
2.False
Posted Date:-2022-05-31 18:01:55
Reciprocal phase shifters give different phase shift in different direction.
1.True
2.False
Posted Date:-2022-06-02 07:26:19
Reflector antennas are widely used to modify radiation patterns of radiating elements.
1.True
2.False
Posted Date:-2022-05-31 18:18:15
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
Posted Date:-2022-05-31 17:43:17
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
Posted Date:-2022-05-31 18:16:23
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
Posted Date:-2022-05-31 18:20:32
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
Posted Date:-2022-05-31 18:08:20
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
Posted Date:-2022-05-31 18:07:18
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
Posted Date:-2022-05-31 18:10:01
The current gain of a BJT ________ with frequency.
1.increases
2.decreases
3.remains constant
4.none of the mentioned
Posted Date:-2022-06-02 07:13:28
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
Posted Date:-2022-05-31 18:05:12
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
Posted Date:-2022-05-31 18:12:57
The hybrid-Ï€ model of a BJT is useful for analysis at all frequency ranges and variation of other transistor parameters.
1.true
2.false
Posted Date:-2022-06-02 07:12:15
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
Posted Date:-2022-05-31 18:04:17
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
Posted Date:-2022-05-31 18:15:50
The modulation technique in which both amplitude and phase of the carrier are varied simultaneously is:
1.ASK
2.BPSK
3.QAM
4.QPSK
Posted Date:-2022-05-31 17:50:03
The noise power will determine the maximum detectable signal level for a receiver.
1.True
2.False
Posted Date:-2022-05-31 17:50:36
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
Posted Date:-2022-05-31 17:34:01
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
Posted Date:-2022-05-31 18:13:28
The number of patterns radiation pattern required to specify the characteristic are :
1.Three
2.Four
3.Two
4.Five
Posted Date:-2022-05-31 18:09:24
The output collector to emitter current of a BJT amplifier is independent of the input base current of the amplifier.
1.true
2.false
Posted Date:-2022-06-02 07:12:52
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
Posted Date:-2022-05-31 18:18:46
The probability of error depends on the ratio of bit energy to noise power density.
1.true
2.false
Posted Date:-2022-05-31 17:45:26
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
Posted Date:-2022-05-31 17:57:03
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
Posted Date:-2022-05-31 18:03:22
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
Posted Date:-2022-05-31 18:10:42
The system bandwidth of a total power radiometer is determined by the:
1.RF amplifier
2. Local oscillator
3. IF filter
4.IF amplifier
Posted Date:-2022-05-31 18:03:54
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
Posted Date:-2022-05-31 17:57:57
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
Posted Date:-2022-05-31 18:21:42
There is no standard to be formed by commercial WLAN products.
1.true
2.false
Posted Date:-2022-05-31 17:48:17
When the separation between two lines that carry the TEM wave approaches λ the wave tends to be radiated.
1.True
2.False
Posted Date:-2022-05-31 18:08:43
WLAN is used for providing connection between a host computer and satellite for communication.
1.true
2.false
Posted Date:-2022-05-31 17:47:51
_____ 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
Posted Date:-2022-06-02 07:25:44
______ 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
Posted Date:-2022-05-31 18:19:31
_______ 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
Posted Date:-2022-05-31 18:15:06
________ 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
Posted Date:-2022-05-31 17:38:25
_________ 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
Posted Date:-2022-05-31 17:37:14
_________ has a constant power spectral density.
1.White noise
2.Gaussian noise
3.Thermal noise
4.Shot noise
Posted Date:-2022-05-31 17:34:46
_________ is a device that converts electrons to photons or vice-versa.
1.Antenna
2.Electron gun
3.Photon amplifier
4.Microwave tube
Posted Date:-2022-05-31 18:07:49
__________ 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 Date:-2022-05-31 18:00:57