Microwave Communication(Electrical Engineering ) Questions and Answers

Question 1. Coupling into and out of a traveling-wave tube can be accompanied by a
  1.    Waveguide match
  2.    Cavity match
  3.    Direct coax-helix match
  4.    All of the above
Explanation:-
Answer: Option D. -> All of the above
Question 2. The antenna separations (in meters) required for optimum operation of a space diversity system can be calculated from:where R = effective earth radius (m) and L = path length (m)
  1.    $${\text{S}} = \frac{{2\lambda {\text{R}}}}{{\text{L}}}$$
  2.    $${\text{S}} = \frac{{3\lambda {\text{R}}}}{{\text{L}}}$$
  3.    $${\text{S}} = \frac{{\lambda {\text{R}}}}{{\text{L}}}$$
  4.    $${\text{S}} = \frac{{\text{L}}}{{\lambda {\text{R}}}}$$
Explanation:-
Answer: Option B. -> $${\text{S}} = \frac{{3\lambda {\text{R}}}}{{\text{L}}}$$
Question 3. When it is desired that short-range targets be clearly seen on a pulsed-radar set, it is important that the receiver and display system have
  1.    A long time constant
  2.    Low-pass filters
  3.    The shortest possible time
  4.    The restricted high-frequency response
Explanation:-
Answer: Option C. -> The shortest possible time
Question 4. The aquadag coating on the inside of PPI tube is used
  1.    To focus the beam of primary electrons
  2.    To shield the electron beam from unidirectional magnetic
  3.    As a second anode and to prevent the build-up of secondary field
  4.    All of these
Explanation:-
Answer: Option C. -> As a second anode and to prevent the build-up of secondary field
Question 5. What allow microwave to pass in only one direction?
  1.    RF emitter
  2.    Capacitor
  3.    Varactor-triac
  4.    Ferrite emitter
Explanation:-
Answer: Option D. -> Ferrite emitter
Question 6. What is the purpose of the electromagnetic field which surrounds a traveling-wave tube?
  1.    To accelerate the electron
  2.    To velocity modulate the electron beam
  3.    To keep the electrons from spreading out
  4.    To slow down the signal on the helix
Explanation:-
Answer: Option C. -> To keep the electrons from spreading out
Question 7. The Gunn diode oscillator
  1.    Is capable of generating continuous microwave power of the order of kilowatt
  2.    Generates frequencies which are below 100 MHz
  3.    Operates over a positive resistance characteristic
  4.    Depends on the formation of charge domain
Explanation:-
Answer: Option D. -> Depends on the formation of charge domain
Question 8. Theoretically electromagnetic radiation field strength varies in inverse proportion to the square of the distance, but when atmospheric attenuation effects and the absorption of the terrain are taken into account the attenuation can be as high as the inverse ___________ power of the distance.
  1.    Third
  2.    Fourth
  3.    Fifth
  4.    Sixth
Explanation:-
Answer: Option D. -> Sixth
Question 9. In a radar-set receiver, the usual mixer stage is
  1.    And FET
  2.    A tunnel diode
  3.    A silicon crystal
  4.    A Rochelle salts crystal
Explanation:-
Answer: Option C. -> A silicon crystal
Question 10. A reflex klystron is oscillating at the frequency of its resonant cavity. If the reflector voltage is made slightly less negative, the
  1.    Oscillation will cease
  2.    Output power would increase
  3.    The frequency will decrease
  4.    Bunching would occur earlier in time
Explanation:-
Answer: Option C. -> The frequency will decrease
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