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Home ‣ Electronics and Communication Engineering ‣ Microwave Communication Comments
  • Question

  • A magnetron requires an external magnetic field with flux lines parallel to axis of cathode


  • Options
  • A. True
  • B. False

  • Correct Answer
  • True 

    Explanation
    It is somewhat similar to TWT and can deliver microwave power over a wide frequency band.

    It has an electron gun and a helix structure. However the interaction between electron beam and RF wave is different than in TWT.

    The growing RF wave travels in opposite direction to the electron beam.

    The frequency of wave can be changed by changing the voltage which controls the beam velocity.

    Moreover the amplitude of oscillations can be decreased continuously to zero by changing the beam current.

    It features are:

    1. Frequency range - 1 GHz to 1000 GHz.

    2. Power output - 10 mV to 150 mW (continuous wave) 250kW (pulsed).

    It is used as signal source in transmitters and instruments.

    Microwave Communication problems

    Search Results

    • 1. The directive gain of a transmitting antenna is proportional to

    • Options
    • A. its cross-sectional area
    • B. square of cross-sectional area
    • C. square root of cross-sectional area
    • D. cube root of cross-sectional area
      • Discuss
    • 2. Which one of the following is transferred locking electron device C antenna?

    • Options
    • A. BARITT diode
    • B. IMPATT diode
    • C. Gunn diode
    • D. Step recovery diode
      • Discuss
    • 3. If a line having Z0 = 300 ? 0 W is open circuited at far end, VSWR is

    • Options
    • A. 0
    • B. 1
    • C. ?
    • D. 2
      • Discuss
    • 4. The main feature of a parametric amplifier is

    • Options
    • A. low noise
    • B. very high gain
    • C. broad bandwidth
    • D. both (b) and (c)
      • Discuss
    • 5. In microwave system the function of mode filter is

    • Options
    • A. to suppress modes with lower cut off frequencies
    • B. to suppress modes with higher cut off frequencies
    • C. to change mode of wave transmission
    • D. both (b) and (c)
      • Discuss
    • 6. High speed logic circuits use

    • Options
    • A. pulses with very small width
    • B. pulses with very large width
    • C. pulses whose width is neither small nor large
    • D. either (b) or (c)
      • Discuss
    • 7. The total field developed by an antenna array at a distant point is

    • Options
    • A. phasor sum of fields produced by individual antennas of the array
    • B. algebraic sum of fields produced by individual antennas of the array
    • C. either (a) or (b) depending on type of array
    • D. neither (a) nor (b)
      • Discuss
    • 8. A (75 - J50) ohm load is connected to a coaxial of Z0 = 75 ohm at 10 GHz. The best method of matching is to connect

    • Options
    • A. an inductance at load
    • B. a short circuited stub at load
    • C. a short circuited stub at specific distance from load
    • D. a capacitance at specific distance from load
      • Discuss
    • 9. Assertion (A): The condition of minimum distortion in a transmission line is L = RC/G.

      Reason (R): Line loading means addition of inductance to satisfy the condition L = RC/G.


    • Options
    • A. Both A and R are correct and R is correct explanation of A
    • B. Both A and R are correct but R is not correct explanation of A
    • C. A is correct but R is wrong
    • D. A is wrong but R is correct
      • Discuss
    • 10. To couple a coaxial line to a parallel wire line it is best to use

    • Options
    • A. slotted line
    • B. balun
    • C. directional coupler
    • D. ?/4 transformer
      • Discuss

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