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ECE :: Microwave Communication

  1. Slotted line can be used for measurement of high frequencies

  2. A.
    True
    B.
    False

  3. In a waveguide the dielectric region is generally

  4. A.
    air
    B.
    magnetic material
    C.
    brass
    D.
    mica

  5. In directional coupler of the given figure, the terms |S14| and |S23| of scattering matrix are nearly

  6. A.
    1 each
    B.
    0.5 each
    C.
    0.1 each
    D.
    1 and 0.5 respectively

  7. A line is excited by a 100 V, 200 ohm source and is terminated by 100 Ω resistance. If the voltage on line reaches steady value in 80 ns, the natural resonant frequency is

  8. A.
    100 MHz
    B.
    50 MHz
    C.
    12.5 MHz
    D.
    6.25 MHz

  9. A line of length slightly longer than and open circuited at far end behaves as

  10. A.
    inductance L
    B.
    capacitance C
    C.
    L and C in series
    D.
    L and C in parallel

  11. The most commonly used magnetron is

  12. A.
    cylindrical
    B.
    parallel plate
    C.
    inclined plate
    D.
    flat plate

  13. The effect of earth's magnetic field on radiowaves is minimum when

  14. A.
    the electric field lines of radio waves and flux line of earth's magnetic field are in the same direction
    B.
    the electric field lines of radio waves and flux lines of earth's magnetic field are at right angles
    C.
    the electric field lines of radiowaves and flux lines of earth's magnetic field oppose each other
    D.
    both (b) and (c)

  15. A line of characteristic impedance Z0 branches into two line each with characteristic impedance Z0. The refracted voltage is

  16. A.
    zero
    B.
    infinite
    C.
    equal to incident voltage
    D.
    two third of incident voltage

  17. The resistance values of a PIN diode under positive bias and negative bias respectively are about

  18. A.
    a few ohms and a kilo ohms
    B.
    about 100 ohms and 1000 ohms
    C.
    about 0.1 ohm and 100 ohms
    D.
    about 1000 ohms and 10000 ohms

  19. A PIN diode can be used

  20. A.
    as a shunt mounted switch
    B.
    as a series mounted switch
    C.
    both as series or shunt mounted switch
    D.
    non of the above