# ELECTRONICS IMPORTANT MCQ PDF-Antenna & Wave Propagation 2

1)   According to
depth of penetration, what is the percentage proportion of attenuated
wave w.r.t its original value?

a. 17%
b. 27%
c. 37%
d. 57%

2)   Linear polarization can be obtained only if the wave consists of ________
a. Ex
b. Ey
c. Both Ex & Ey & in phase
d. Both Ex & Ey & out of phase

 ANSWER: Both Ex & Ey & in phase
3)   When an
electromagnetic wave travels from transmitter to receiver, which
factor/s affect/s the propagation level?

a. Curvature of earth
b. Roughness of earth
c. Magnetic field of earth
d. All of the above

4)   For avoiding ground losses, better is the surface conductivity, less is the __________
a. Attenuation
b. Phase velocity
c. Propagation constant
d. Tilt angle

5)   On which factors of earth does the magnitude of tilt angle depend in surface wave?
A. Permittivity
B. Conductivity
C. Resistivity
D. Reflectivity

a. A & B
b. C & D
c. A & C
d. B & D

6)   What is the
direction of varying orientation of polarized surface wave at the earth
surface in a wave tilt mechanism?

a. Horizontal
b. Vertical
c. Diagonal
d. Opposite

7)   Which layer has the atmospheric conditions exactly opposite to that of standard atmosphere?
a. Depression layer
b. Regression layer
c. Inversion layer
d. Invasion layer

8)   If the maximum electron density for F-layer in ionosphere is 4 x 106 electrons/cm3, then what will be the critical frequency of EM wave for F-layer?
a. 4 MHz
b. 9 MHz
c. 18 MHz
d. 25 MHz

9)   According to Secant law, which frequency is greater than critical frequency by a factor of secθi?

a. MUF
b. LUF
c. OWF
d. UHF

10)   How is the effect of selective fading reduced?
A. By high carrier reception
B. By low carrier reception
C. By single side band system
D. By double side band system

a. A & C
b. B & D
c. A & D
d. B & C

11)   In lens antenna, what kind of wave energy is transformed into plane waves?
a. Convergent
b. Divergent
c. Contingent
d. Congruent

12)   What is the functioning role of an antenna in receiving mode?
b. Converter
c. Sensor
d. Inverter

13)   In radio communication link, what is the shape/nature of waves generated by transmitting antenna?
a. Spherical
b. Plane
c. Triangular
d. Square

14)   Which among the following elucidate the generation of electromagnetic waves?
A. Ampere’s law
C. Gauss’s law
D. Kirchoff’s law

a. A & B
b. B & C
c. A & C
d. B & D

15)   If an antenna draws 12 A current and radiates 4 kW, then what will be its radiation resistance?
a. 22.22 ohm
b. 27.77 ohm
c. 33.33 ohm
d. 39.77 ohm

16)   Under which conditions of two unit vectors, the polarization loss factor (PLF) is equal to unity?
a. Perpendicular
b. Perfectly aligned
c. Angle inclination (Ψp)
d. All of the above

17)   Which property/ies of antenna is/are likely to be evidenced in accordance to Reciprocity theorem?
a. Equality of impedances
b. Equality of directional patterns
c. Equality of effective lengths
d. All of the above

18)   Self impedance of an antenna is basically __________
a. Its input impedance during the removal of all other antennas
b. Its impedance by taking into consideration the consequences of other antennas
c. Both a and b
d. None of the above

 ANSWER: Its input impedance during the removal of all other antennas
19)   In solution
evaluation process of inhomogeneous vector potential wave equation, if
points are completely removed from the source, then by which factor does
the time varying field & static solution differ?

a. e-jkr
b. ejkr
c. e-jk/r
d. e(jk + r)

20)   Which among the below mentioned magnetic quantities is/are dependent on media/medium?
a. B
b. H
c. Both a and b
d. None of the above

21)   The concept
of magnetic vector potential finds its major application in deriving
expression of magnetic field intensity especially for ______

a. Real fields
b. Imaginary fields
c. Complex fields
d. None of the above

22)   If J & M are active at the same time, which principle theorem is used for field estimation?
a. Reciprocity
b. Superposition
c. Causality
d. Relativity

23)   A dipole
Ω. What would be the power radiated by an antenna?

a. 90 kW
b. 135 kW
c. 180 kW
d. 200 kW

24)   What is/are the major applications of an infinitesimal dipole that contribute/s to its analysis?
a. Field pattern estimation due to any length of antenna
b. Improvement in radiation resistance by increasing dipole length
c. Both a and b
d. None of the above

25)   What is /are the advantages of using ferrite loops?
A. Increase in Magnetic field intensity
C. Decrease in Magnetic field intensity

a. A & B
b. C & D
c. A & D
d. B & C

26)   In an electrically large loop, an overall length of the loop is equal to ______
a. λ/2
b. λ
c. λ/10
d. λ/50

27)   How do the elements of an active region behave?
a. Inductive
b. Capacitive
c. Resistive
d. None of the above

28)   By how many
times is an input impedance of a folded dipole at resonance greater than
that of an isolated dipole with same length as one of its sides?

a. 2
b. 3
c. 4
d. 6

29)   Which mode
of radiation occurs in an helical antenna due to smaller dimensions of
helix as compared to a wavelength?

a. Normal
b. Axial
c. Both a and b
d. None of the above

30)   A
rectangular horn antenna operating at 4GHz has the wavelength of 0.075m
and gain of about 13dBi. What will be its required capture area?

a. 0.0149 m2
b. 0.0475 m2
c. 0.5521 m2
d. 0.9732 m2

1. Emenegn Limenh December 10, 2017