Antenna and wave propagation MCQ question and answer.

 Antenna and wave propagation basic question and Answer for exam preparation.

Electronics and communication engineering field Antenna and wave propagation MCQ (Multiple Choice Question) question and answer for exam and interview preparation 👇👇

1. The relation between vector magnetic potential and current density is given by......

A) ∇×A=H
B) ∇2 A=-μJ
C) ∇2 A=∇×H
D) ∇.A=J

... Answer is B)
Explanation : Magnetic Flux density B is expressed as B=∇×A Taking curl on both sides, we get ∇×B=∇×(∇×A ) = ( ∇.A)∇-(∇.∇)A From Maxwell’s equation, ∇.B=0 =>∇.A=0 ⇨ ∇×B= -∇2 A and B= μH , ∇×H=J ⇨ ∇×μH= -∇2A ⇨ ∇2 A=-μJ.

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2. According to Siegel and Labus, antennas can be treated as

A) Opened out transmission line
B) Shorted transmission line
C) Earthed transmission line
D) Closed transmission line

... Answer is A)
Opened out transmission line.

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3. The ratio of radiation intensity in a given direction from antenna to the radiation intensity over all directions is called as.....

A) Array Factor
B) Radiation power density
C) Gain of antenna
D) Directivity

... Answer is D)
Explanation : Directivity of antenna is defined as the ratio of radiation intensity in a given direction from antenna to the radiation intensity over all directions. D=UmaxU0. Radiation Intensity is power radiated from an antenna for unit solid angle. U0=wr.r2wattssteradians. Gain of antenna is ratio of radiation intensity in given direction to the radiation intensity of isotropic radiation. Array factor is a function of geometry of array and the excitation phase.

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4. What is the wavelength of Super high frequency (SHF) especially used in Radar & satellite communication?

A) 0.1 cm – 1 cm
B) 10 cm – 1 m
C) 1 m – 10 m
D) 1 cm – 10 cm

... Answer is D)
1 cm – 10 cm

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5. Equivalent circuit representation of an antenna is

A) Series R, L parallel to C
B) Series R, L, C
C) Parallel R, C series to L
D) Parallel R, L, C

... Answer is B)
Antenna is represented by a series R, L, C equivalent circuit. Antenna is used for impedance matching and acts like a transducer.

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6. Which among the following is an application of high frequency?

A) Subsurface communication
B) Radio navigation
C) SONAR
D) Facsimile

... Answer is D)
Fescimile is an application of high frequency

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7. The axis of back lobe makes an angle of 180° with respect to the beam of an antenna.

A) True
B) False
.........
.........

... Answer is A)
Explanation: The axis of back lobe is opposite to the main lobe. So it makes 180° with beam of antenna. It is also a side lobe which is at 180 to main lobe.

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8. In which kind of waveform is the phase velocity defined?

A) Square
B) Rectangular
C) Sinusoidal
D) Square

... Answer is c)
No Explanation

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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) 90 km – 130 km
B) 90 km - 120 km
C) 140 km – 200 km
D) 30 km - 50 km

... Answer is A)
No Explanation

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10. Which ionization layer exists during day time & usually vanishes at night due to highest recombination rate?

A) Normal E-Region
B) Appleton region
C) Sporadic E-region
D) D - Region

... Answer is D)
No Explanation

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