ELECTRONICS IMPORTANT MCQ PDF-Antenna & Wave Propagation 1

1)   What is the wavelength of Super high frequency (SHF) especially used in Radar & satellite communication?
a. 1 m – 10 m
b. 1 cm – 10 cm
c. 10 cm – 1 m
d. 0.1 cm – 1 cm

ANSWER: 1 cm – 10 cm
2)   Which among the following is an application of high frequency?
a. SONAR
b. Subsurface communication
c. Radio navigation
d. Facsimile

ANSWER: Facsimile
3)   Wavefront is basically a locus of points acquiring similar _______
a. Phase
b. Frequency
c. Amplitude
d. Wave equation

ANSWER: Phase
4)   In which kind of waveform is the phase velocity defined?
a. Sinusoidal
b. Rectangular
c. Square
d. Triangular

ANSWER: Sinusoidal
5)   Which among the following is/are not present in free space?
a. Solid bodies
b. Ionized particles
c. Interference of normal radiation & radio wave propagation
d. All of the above

ANSWER: All of the above
6)   Power density is basically termed as ________ power per unit area
a. Reflected
b. Refracted
c. Radiated
d. Diffracted

ANSWER: Radiated
7)   If the path
difference of two waves with single source traveling by different paths
to arrive at the same point, is λ/2, what would be the phase difference
between them?

a. β x (λ/2)
b. β / (λ/2)
c. β + (λ/2)
d. β – (λ/2)

ANSWER: β x (λ/2)
8)   Which
ionization layer exists during day time & usually vanishes at night
due to highest recombination rate?

a. D-region
b. Normal E-region
c. Sporadic E-region
d. Appleton region

ANSWER: D-region
9)   What is the
possible range of height for the occurrence of sporadic E-region with
respect to normal E-region?

a. 20 km – 50 km
b. 45 km – 85 km
c. 90 km – 130 km
d. 140 km – 200 km

ANSWER: 90 km – 130 km
10)   F2 layer of appleton region acts as a significant reflecting medium for _____ frequency radio waves
a. Low
b. Moderate
c. High
d. All of the above

ANSWER: High
11)   The knowledge of which parameter is sufficient for deriving the time varying electromagnetic field?
a. Electric field intensity
b. Magnetic field intensity
c. Current density
d. Power density

ANSWER: Current density
12)   According to Webster’s dictionary, what is an antenna?
a. Impedance matching device
b. Sensor of electromagnetic waves
c. Transducer between guided wave & free space wave
d. Metallic device for radiating or receiving radio waves

ANSWER: Metallic device for radiating or receiving radio waves
13)   Under which conditions of charge does the radiation occur through wire antenna?
a. For a charge with no motion
b. For a charge moving with uniform velocity with straight & infinite wire
c. For a charge oscillating in time motion
d. All of the above

ANSWER: For a charge oscillating in time motion
14)   In a
non-isotropic directional antenna, which radiating lobe axis makes an
angle of 180° w.r.t. major beam of an antenna?

a. Minor lobe
b. Side lobe
c. Back lobe
d. None of the above

ANSWER: Back lobe
15)   At which angles does the front to back ratio specify an antenna gain?
a. 0° & 180°
b. 90° & 180°
c. 180° & 270°
d. 180° & 360°

ANSWER: 0° & 180°
16)   Which among
the following defines the angular distance between two points on each
side of major lobe especially when the radiation drops to zero?

a. Half power beam width (HPBW)
b. First null beam width (FNBW)
c. Side lobe level (SLL)
d. Front to back ratio (FBR)

ANSWER: First null beam width (FNBW)
17)   If an observation point is closely located to the source, then the field is termed as ________
a. Induced
b. Radiated
c. Reflected
d. Far-field

ANSWER: Induced
18)   Which auxiliary functions assist in solving the radiation problem by evaluation of E & H using sources J & M?
a. Scalar potentials
b. Vector potentials
c. Gradient potentials
d. Divergence potentials

ANSWER: Vector potentials
19)   Which operations are performed by vector potentials (A, F) over the radiated fields (E & H)?
a. Addition
b. Subtraction
c. Differentiation
d. Integration

ANSWER: Differentiation
20)   Which waveform plays a crucial role in determining the radiation pattern of the dipole/wire antennas?
a. Current
b. Voltage
c. Frequency
d. Phase

ANSWER: Current
21)   How are the infinitesimal dipoles represented in terms of antenna length and signal wavelength?
a. l ≤ (λ /50)
b. (λ/50 ) < l ≤ (λ /10)
c. l = λ/2
d. None of the above

ANSWER: l ≤ (λ /50)
22)   In flared transmission line, the radiation phenomenon increases due to ________ in flaring
a. Increase
b. Decrease
c. Stability
d. None of the above

ANSWER: Increase
23)   Which pattern is generated due to plotting of square of amplitude of an electric field?
a. Field Pattern
b. Voltage Pattern
c. Power Pattern
d. All of the above

ANSWER: Power Pattern
24)   In an electrically small loops, the overall length of the loop is ______ one-tenth of a wavelength.
a. Less than
b. Equal to
c. Greater than
d. None of the above

ANSWER: Less than
25)   On which factor/s do/does the radiation field of a small loop depend?
a. Shape
b. Area
c. Both a and b
d. None of the above

ANSWER: Area
26)   From the radiation point of view, small loops are _________radiators
a. Poor
b. Good
c. Better
d. Excellent

ANSWER: Poor
27)   According to
the directivity of a small loop, which value of ‘θ’ contributes to
achieve the maximum value of radiation intensity (Umax)?

a.
b. 90°
c. 180°
d. 270°

ANSWER: 90°
28)   In which
kind of array configuration, the element locations must deviate or
adjust to some nonplaner surface like an aircraft or missile?

a. Linear
b. Planer
c. Conformal
d. All of the above

ANSWER: Conformal
29)   What is the nature of radiation pattern of an isotropic antenna?
a. Spherical
b. Dough-nut
c. Elliptical
d. Hyperbolic

ANSWER: Spherica
30)   In broadside
array, all the elements in the array should have similar
_______excitation along with similar amplitude excitation for maximum
radiation.

a. Phase
b. Frequency
c. Current
d. Voltage

ANSWER: Phase
31)   Which among the following is regarded as a condition of an ordinary endfire array?
a. α < βd
b. α > βd
c. α = ±βd
d. α ≠ ±βd

ANSWER: α = ±βd
32)   Which mode of propagation is adopted in HF antennas?
a. Ionospheric
b. Ground wave
c. Tropospheric
d. All of the above

ANSWER: Ionospheric
33)   For which band/s is the space wave propagation suitable over 30 MHz?
a. VHF
b. SHF
c. UHF
d. All of the above

ANSWER: All of the above
34)   If the tower antenna is not grounded, which method of excitation is/are applicable for it?
a. Series
b. Shunt
c. Both a and b
d. None of the above

ANSWER: Series
35)   In
ungrounded antennas, if an excitation is applied directly across the
base insulator, then on which factor/s would the voltage across the
insulator depend?

a. Power delivered to antenna
b. Power factor of impedance
c. Both a and b
d. None of the above

ANSWER: Both a and b

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ELECTRONICS IMPORTANT MCQ PDF-Antenna & Wave Propagation 2
Mechanical Engineering Important MCQ PDF-Fluid Mechanics 2 & 3

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