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
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2) Which among the following is an application of high frequency?
a. SONAR
b. Subsurface communication
c. Radio navigation
d. Facsimile
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3) Wavefront is basically a locus of points acquiring similar _______
a. Phase
b. Frequency
c. Amplitude
d. Wave equation
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4) In which kind of waveform is the phase velocity defined?
a. Sinusoidal
b. Rectangular
c. Square
d. Triangular
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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
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6) Power density is basically termed as ________ power per unit area
a. Reflected
b. Refracted
c. Radiated
d. Diffracted
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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)
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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
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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
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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
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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
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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
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Answer
Explanation
Related Ques
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ANSWER: Metallic device for radiating or receiving radio waves
Explanation:
No explanation is available for this question!
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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
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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
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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°
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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)
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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
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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
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19) Which operations are performed by vector potentials (A, F) over the radiated fields (E & H)?
a. Addition
b. Subtraction
c. Differentiation
d. Integration
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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
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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
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22) In flared transmission line, the radiation phenomenon increases due to ________ in flaring
a. Increase
b. Decrease
c. Stability
d. None of the above
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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
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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
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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
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26) From the radiation point of view, small loops are _________radiators
a. Poor
b. Good
c. Better
d. Excellent
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27) According to the directivity of a small loop, which value of 'θ' contributes to achieve the maximum value of radiation intensity (Umax)?
a. 0°
b. 90°
c. 180°
d. 270°
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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
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29) What is the nature of radiation pattern of an isotropic antenna?
a. Spherical
b. Dough-nut
c. Elliptical
d. Hyperbolic
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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
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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
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32) Which mode of propagation is adopted in HF antennas?
a. Ionospheric
b. Ground wave
c. Tropospheric
d. All of the above
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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
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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
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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
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