1. An Antenna that is circularly polarized is the
a) Helical
b) Small circular loop
c) Parabolic reflector
d) Yagi-uda
Ans: Option a)
2. The standard reference antenna for the directive gain is the
a) Infinitesimal dipole
b) Isotropic antenna
c) Elementary doublet
d) Half-wave dipole
Ans: Option b)
3. Top loading is sometimes used with an antenna in order to increase
a) Effective height
b) Bandwidth
c) Beam width
d) Input Capacitance
Ans: Option a)
4. A helical antenna is used for satellite tracking because of its
a) Circular polarization
b) Maneuverability
c) Broad bandwidth
d) Good front-to-back ratio
Ans: Option a)
5. The directivity of an isotropic antenna is
a) Zero
b) Less than unity
c) Unity
d) Infinity
Ans: Option c)
6. In order to receive a vertically polarized wave the conductor of the dipole should be mounted
a) Horizontally
b) Vertically
c) At an angle of 45o
d) None of these
Ans: Option b)
7. For a dipole antenna
a) The radiation intensity is maximum along the normal to the dipole axis
b) The current distribution along its length is uniform irrespective of the length
c) The effective length equals to its physical length
d) The input impedance is independent of the location of the feed point
Ans: Option a)
8. Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are fed with currents of equal phase and magnitude, the number of lobes in the radiation pattern in the horizontal plane is
a) 2
b) 4
c) 6
d) 8
Ans: Option d)
9. Consider the following statements:
1.Antenna radiates energy
2. An antenna is a transition device or transducer between a guided wave and free space or vice-versa
3. The resonators and transmission lines store energy
4. An antenna converts electromagnetic signal into current and vice-versa
Which of the following statements are correct?
a) 1,2 and 4 only
b) 1,2 and 3 only
12. Far field of an antenna varies with distance r as
a) 1/r
b) 1/r2
Ans: Option a)
13. Cassegrain feed is used with a parabolic antenna in order to
a) increase the gain of the system
b) Increase the beamwidth of the system
c) Reduce the size of the main reflector
d) Allow the feed to be placed at a convenient point
Ans: Option d)
14. For a plane wave propagating in an unbounded medium (free space), the minimum angle between electric and magnetic field vectors is
a) 0
b) 60
c) 90
d) 180
Ans: Option c)
15. The main difference between the operation of transmission lines and waveguides is that
a) The latter are not distributed, like transmission line
b) The former can use stubs ans quarter-wave transformers, unlike the latter
c) Transmission lines use the principal mode of propagation and therefore do not suffer from low frequency cutoff
d) Terms such as impedance matching and standing wave ratio cannot be applied to waveguides
Ans: Option c)
16. The wavelength of a wave in a waveguide
a) is greater than in free space
b) depends only on the waveguide dimensions and the free space wavelength
c) is inversely proportional to the phase velocity
d) is directly proportional to the group velocity
Ans: Option a)
17. A transmission line whose characteristic impedance is a pure resistance
a) must be a lossless line
b) must be a distortionless line
c) May not be a lossless line
d) May not be a distortionless line
Ans: Option a)
18. A 300 Ω line is terminated in a load impedance of 100 + j 200 Ω. The voltage reflection coefficient is
a) 0.6325 ∟108
b) 0.7 ∟30
c) 0.27 + j 0.196
d) 0.377 ∟42.7
Ans: Option a)
19. Diffraction of electromagnetic waves
a) is caused by reflections from the ground
b) arises only with spherical wavefronts
c) will occur when the wave pass through a large slot
d) will occur around the edge of a sharp obstacle
Ans: Option d)
20. An electromagnetic wave incident on a perfect conductor is
a) Entirely reflected
b) Fully transmitted
c) Partially transmitted
d) None of these
Ans: Option a)
21. Which one of the following sets of equations is independent in maxwell's equations?
a) Two curl equations
b) two divergence equations
c) Both the curl and divergence equations
d) two curl equations combined with the continuity equation
Ans: Option c)
22. Consider the following statements:
For electromagnetic waves propagating in free space:
1. Electric field is perpendicular to direction of propagation
2. Electric field is along the direction of propagation
3. Magnetic field is perpendicular to direction of propagation
4. Magnetic field is along the direction of propagation
Which of these statements are correct?
a) 1 and 3
b) 1 and 4
c) 2 and 3
d) 2 and 4
Ans: Option a)
23. The dominant mode in a rectangular waveguide is TE10 because this mode has
a) No attenuation
b) No cut-off
c) No magnetic field component
d) The highest cut-off wavelength
Ans: Option d)
24. 8-point charges of 1nC each are located at the corners of a cube in free space that on 1m on a side, then
at the center is
a) 0 V/m
b) 5 V/m
c) 4 V/m
d) -5 V/m
Ans: Option a)
25. A 50 Ω lossless transmission line has a pure reactance of j100 Ω as its load. The VSWR in the line is
a) 0
b) Infinity
c) 50
d) 100 + j 100
Ans: Option b)
26. Calculate the front-to-back ratio of an antenna in dB which radiates 3 kW in its optimum direction and 500 watts in the opposite direction
a) 0.782
b) 7.782
c) -22.22
d) none of these
Ans: Option b)
27. An uniform plane wave incident normally on a plane surface of dielectric material is reflected with a VSWR of 3. What is the percentage of incident power that is reflected.
a) 10%
b) 25 %
c) 50%
d) 75%
Ans: Option b)
28. Two coaxial cables 1 and 2 are filled with different dielectric constants ϵr1 and ϵr2 respectively. The ratio of the wavelengths in the two cables λ1/ λ2 is
a) √( ϵr1/ ϵr2)
b) √( ϵr2/ ϵr1)
c) ϵr1/ ϵr2
d) ϵr2/ ϵr1
Ans: Option b)
29. Which of the following is zero?
a) Grad div
b) Div grad
c) Curl grad
d) Curl curl
Ans: Option c)
30. Which is not an example of convection current?
a) A moving charged belt
b) Electronic movement in a vacuum tube
c) An electron beam in a television tube
d) Electric current flowing in a copper wire
Ans: Option d)
31. One of the following is not a source of magnetostatic fields
a) A dc current in a wire
b) A Permanent magnet
c) An accelerated charge
d) An Electric filed linearly changing with time
Ans: Option c)
32. Which of thse statements is not characteristic of a static magnetic field?
a) It is solenoidal
b) It is conservative
c) It has no sinks or sources
d) Magnetic flux lines are always closed
Ans: Option b)
Static magnetic field is not conservative
33. Two thin parallel wires carry currents along the same direction. The force experienced by one due to the other is
a) Parallel to the lines
b) Perpendicular to the lines and attractive
c) Perpendicular to the lines and repulsive
d) Zero
Ans: Option b)
a) Helical
b) Small circular loop
c) Parabolic reflector
d) Yagi-uda
Ans: Option a)
2. The standard reference antenna for the directive gain is the
a) Infinitesimal dipole
b) Isotropic antenna
c) Elementary doublet
d) Half-wave dipole
Ans: Option b)
3. Top loading is sometimes used with an antenna in order to increase
a) Effective height
b) Bandwidth
c) Beam width
d) Input Capacitance
Ans: Option a)
4. A helical antenna is used for satellite tracking because of its
a) Circular polarization
b) Maneuverability
c) Broad bandwidth
d) Good front-to-back ratio
Ans: Option a)
5. The directivity of an isotropic antenna is
a) Zero
b) Less than unity
c) Unity
d) Infinity
Ans: Option c)
6. In order to receive a vertically polarized wave the conductor of the dipole should be mounted
a) Horizontally
b) Vertically
c) At an angle of 45o
d) None of these
Ans: Option b)
7. For a dipole antenna
a) The radiation intensity is maximum along the normal to the dipole axis
b) The current distribution along its length is uniform irrespective of the length
c) The effective length equals to its physical length
d) The input impedance is independent of the location of the feed point
Ans: Option a)
8. Two isotropic antennas are separated by a distance of two wavelengths. If both the antennas are fed with currents of equal phase and magnitude, the number of lobes in the radiation pattern in the horizontal plane is
a) 2
b) 4
c) 6
d) 8
Ans: Option d)
9. Consider the following statements:
1.Antenna radiates energy
2. An antenna is a transition device or transducer between a guided wave and free space or vice-versa
3. The resonators and transmission lines store energy
4. An antenna converts electromagnetic signal into current and vice-versa
Which of the following statements are correct?
a) 1,2 and 4 only
b) 1,2 and 3 only
c) 2,3 and 4 only
d) 1,2,3 and 4
Ans: Option a)
10. An antenna can be made more directional by
a) Increasing its diameter
b) Increasing frequency of transmission
c) either a) or b)
d) none of the above
Ans: Option c)
11. The radiation resistance of a circular loop of a turn is 0.01 Ω. The radiation resistance of five turns of such a loop will be
a) 0.002 Ω
b) 0.01 Ω
c) 0.05 Ω
d) 0.25 Ω
Ans: Option c)
d) 1,2,3 and 4
Ans: Option a)
10. An antenna can be made more directional by
a) Increasing its diameter
b) Increasing frequency of transmission
c) either a) or b)
d) none of the above
Ans: Option c)
11. The radiation resistance of a circular loop of a turn is 0.01 Ω. The radiation resistance of five turns of such a loop will be
a) 0.002 Ω
b) 0.01 Ω
c) 0.05 Ω
d) 0.25 Ω
Ans: Option c)
12. Far field of an antenna varies with distance r as
a) 1/r
b) 1/r2
Ans: Option a)
13. Cassegrain feed is used with a parabolic antenna in order to
a) increase the gain of the system
b) Increase the beamwidth of the system
c) Reduce the size of the main reflector
d) Allow the feed to be placed at a convenient point
Ans: Option d)
14. For a plane wave propagating in an unbounded medium (free space), the minimum angle between electric and magnetic field vectors is
a) 0
b) 60
c) 90
d) 180
Ans: Option c)
15. The main difference between the operation of transmission lines and waveguides is that
a) The latter are not distributed, like transmission line
b) The former can use stubs ans quarter-wave transformers, unlike the latter
c) Transmission lines use the principal mode of propagation and therefore do not suffer from low frequency cutoff
d) Terms such as impedance matching and standing wave ratio cannot be applied to waveguides
Ans: Option c)
16. The wavelength of a wave in a waveguide
a) is greater than in free space
b) depends only on the waveguide dimensions and the free space wavelength
c) is inversely proportional to the phase velocity
d) is directly proportional to the group velocity
Ans: Option a)
17. A transmission line whose characteristic impedance is a pure resistance
a) must be a lossless line
b) must be a distortionless line
c) May not be a lossless line
d) May not be a distortionless line
Ans: Option a)
18. A 300 Ω line is terminated in a load impedance of 100 + j 200 Ω. The voltage reflection coefficient is
a) 0.6325 ∟108
b) 0.7 ∟30
c) 0.27 + j 0.196
d) 0.377 ∟42.7
Ans: Option a)
19. Diffraction of electromagnetic waves
a) is caused by reflections from the ground
b) arises only with spherical wavefronts
c) will occur when the wave pass through a large slot
d) will occur around the edge of a sharp obstacle
Ans: Option d)
20. An electromagnetic wave incident on a perfect conductor is
a) Entirely reflected
b) Fully transmitted
c) Partially transmitted
d) None of these
Ans: Option a)
21. Which one of the following sets of equations is independent in maxwell's equations?
a) Two curl equations
b) two divergence equations
c) Both the curl and divergence equations
d) two curl equations combined with the continuity equation
Ans: Option c)
22. Consider the following statements:
For electromagnetic waves propagating in free space:
1. Electric field is perpendicular to direction of propagation
2. Electric field is along the direction of propagation
3. Magnetic field is perpendicular to direction of propagation
4. Magnetic field is along the direction of propagation
Which of these statements are correct?
a) 1 and 3
b) 1 and 4
c) 2 and 3
d) 2 and 4
Ans: Option a)
23. The dominant mode in a rectangular waveguide is TE10 because this mode has
a) No attenuation
b) No cut-off
c) No magnetic field component
d) The highest cut-off wavelength
Ans: Option d)
24. 8-point charges of 1nC each are located at the corners of a cube in free space that on 1m on a side, then
at the center isa) 0 V/m
b) 5 V/m
c) 4 V/m
d) -5 V/m
Ans: Option a)
25. A 50 Ω lossless transmission line has a pure reactance of j100 Ω as its load. The VSWR in the line is
a) 0
b) Infinity
c) 50
d) 100 + j 100
Ans: Option b)
26. Calculate the front-to-back ratio of an antenna in dB which radiates 3 kW in its optimum direction and 500 watts in the opposite direction
a) 0.782
b) 7.782
c) -22.22
d) none of these
Ans: Option b)
27. An uniform plane wave incident normally on a plane surface of dielectric material is reflected with a VSWR of 3. What is the percentage of incident power that is reflected.
a) 10%
b) 25 %
c) 50%
d) 75%
Ans: Option b)
28. Two coaxial cables 1 and 2 are filled with different dielectric constants ϵr1 and ϵr2 respectively. The ratio of the wavelengths in the two cables λ1/ λ2 is
a) √( ϵr1/ ϵr2)
b) √( ϵr2/ ϵr1)
c) ϵr1/ ϵr2
d) ϵr2/ ϵr1
Ans: Option b)
29. Which of the following is zero?
a) Grad div
b) Div grad
c) Curl grad
d) Curl curl
Ans: Option c)
30. Which is not an example of convection current?
a) A moving charged belt
b) Electronic movement in a vacuum tube
c) An electron beam in a television tube
d) Electric current flowing in a copper wire
Ans: Option d)
31. One of the following is not a source of magnetostatic fields
a) A dc current in a wire
b) A Permanent magnet
c) An accelerated charge
d) An Electric filed linearly changing with time
Ans: Option c)
32. Which of thse statements is not characteristic of a static magnetic field?
a) It is solenoidal
b) It is conservative
c) It has no sinks or sources
d) Magnetic flux lines are always closed
Ans: Option b)
Static magnetic field is not conservative
33. Two thin parallel wires carry currents along the same direction. The force experienced by one due to the other is
a) Parallel to the lines
b) Perpendicular to the lines and attractive
c) Perpendicular to the lines and repulsive
d) Zero
Ans: Option b)
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