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ECE :: Microwave Communication

  1. The directive gain of a transmitting antenna is

  2. A.
    proportional to wavelength
    B.
    inversely proportional to wavelength
    C.
    proportional to square of wavelength
    D.
    inversely proportional to square of wavelength

  3. A duplexer is used to

  4. A.
    couple two antennas to a transmitter
    B.
    isolate the antenna from the local oscillator
    C.
    prevent interference between two antennas connected to receiver
    D.
    use an antenna for reception or transmission without interference

  5. A branched duplexer requires

  6. A.
    TR tubes
    B.
    ATR tube
    C.
    both TR and ATR tube
    D.
    none of the above

  7. In a backward wave oscillator the wave

  8. A.
    travelling along the line winds itself back and forth
    B.
    progresses only in forward direction
    C.
    progresses only in backward direction
    D.
    either (a) or (c)

  9. A coaxial line has L = 500 nH/m and C = 50 pF/m. The characteristic impedance is

  10. A.
    500 Ω
    B.
    250 Ω
    C.
    100 Ω
    D.
    50 Ω

  11. The main feature of a parametric amplifier is

  12. A.
    low noise
    B.
    very high gain
    C.
    broad bandwidth
    D.
    both (b) and (c)

  13. Assertion (A): PIN diode is commonly used for microwave control.

    Reason (R): A PIN diode uses heavily doped p and n materials.

  14. 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

  15. In a vacuum tube, the transit time of electron between cathode and anode is important at

  16. A.
    low frequencies
    B.
    high frequencies
    C.
    both (a) and (b)
    D.
    frequencies which are neither very low nor very high

  17. Assertion (A): A line of length and short circuited at far end has an input impedance of infinity.

    Reason (R): A line of length and short circuited at far end behaves as a parallel resonant circuit.

  18. 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