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

  • Assertion (A): PIN diode is used as a fast switch.

    Reason (R): PIN diode has very high resistance when reverse biased and very low resistance when forward biased.


  • 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

  • Correct Answer
  • Both A and R are correct and R is correct explanation of A 

    Explanation
    A PIN diode has an intrinsic (i) layer between p and n layers. When reverse bias is applied depletion layers are formed at p-i and i-n junctions.

    The effective/width of depletion layer increases by the width of i layer. It can be used as a voltage controlled attenuator.

    At high frequencies the rectification effect ceases and impedance of diode is effectively that of i layer.

    This impedance varies with the applied bias. It is used in high frequency switching circuits, limiters, modulators etc.

    Microwave Communication problems

    Search Results

    • 1. If a line is open circuited Zin = Z0 tanh (gl).

    • Options
    • A. True
    • B. False
      • Discuss
    • 2. In a microwave coaxial line, the maximum operating frequency is f max and breakdown strength of dielectric is Ed' Then maximum power handling capacity is proportional to

    • Options
    • A.
    • B.
    • C.
    • D.
      • Discuss
    • 3. 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
    • 4. A cavity resonator is

    • Options
    • A. a hollow metallic enclosure
    • B. a hollow enclosure having magnetic material as its walls
    • C. a hollow enclosure having dielectric material as its walls
    • D. either (b) or (c)
      • Discuss
    • 5. Power gain of a multicavity klystron amplifier is

    • Options
    • A. more than 30 dB
    • B. causes retardation of all electrons
    • C. causes acceleration of some electrons and retardation of others
    • D. none of the above
      • Discuss
    • 6. Consider the following applications

      1. Switch
      2. Attenuator
      3. Phase shifter
      4. Oscillator
      In which of the above can a PIN diode be used?

    • Options
    • A. 1 2 3 and 4
    • B. 1 2 and 3 only
    • C. 1 and 2 only
    • D. 2, 3 and 4 only
      • Discuss
    • 7. Roughly the time required for microwave cooking as compared to conventional cooking is

    • Options
    • A. about twice
    • B. about half
    • C. about 10 times
    • D. about one-tenth
      • Discuss
    • 8. Which of the following is wrong for a magic used to tee?

    • Options
    • A. E and H arms are decoupled
    • B. coplanar arms are coupled
    • C. all ports are perfectly matched
    • D. A signal into coplanar arm splits equally between E and H arms
      • Discuss
    • 9. The component in the given figure is

    • Options
    • A. attenuator
    • B. T type low pass filter
    • C. T type high pass filter
    • D. phase shifter
      • Discuss
    • 10. A pulsed radar produces 1 ? sec pulses at a rate of 1000 per second. The duty cycle is

    • Options
    • A. 0.001
    • B. 0.01
    • C. 0.1
    • D. 1
      • Discuss

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