07 Microwave
07 Microwave
07 Microwave
7. Helical antennas are often used for satellite tracking at 15. When electromagnetic waves are propagated in a
VHF because of waveguide, they
a. Fade Margin 27. A waveguide assembly that lets the radar transmitter and
b. Threshold Level receiver share an antenna is called
c. Noise Figure
d. RSL a. translator
b. diplexer
19. The use of redundant system to reduce the effects of c. flip-flop
multipath fading is d. duplexer
a. to eliminate bias distortion 32. The weakest signal the receiver could accept to be
b. to help in the loading of the telegraph lines considered satisfactory.
c. to reduce required signal levels
d. to reshape the pulses after they have become a. threshold
distorted b. fade margin
c. RSL
24. A situation when there is no net change in attenuation or d. NPL
“no gain, no loss” occurs when ______ % of the first fresnel
radius clears a path obstruction in microwave systems. 33. The frequency band from 8 to 12 GHz is known as the
______ band.
a. 45%
b. 60% a. C
c. 75% b. Ku
d. 85% c. X
d. Ka
25. __________ are concentric circular zones about a direct
path of a microwave signal called Huygen’s radiation 34. The difference between the Received Signal Level and
center, forming an imaginary solid called an ellipsoid the FM Improvement Threshold
_______.
a. System Gain
a. temperature zone b. Noise Threshold
b. skip zone c. Fade Margin
c. fresnel zone d. Reliability
b. higher than
35. A Fade Margin of 28 dB has a reliability of c. lower than
d. NOTA
a. 99%
b. 99.9% 45. The following are methods of exciting waveguides except
c. 99.99%
d. 99.999% a. slot coupling
b. antennas
36. Topographical maps are maps used for microwave c. flanges
communications systems design because ________ are d. direct coupling
shown, thereby elevations are known.
a. latitudes 46. Higher order mode-waveguides are not used in practice
b. longitudes because they have _______ cut-off frequencies.
c. contour lines
d. scales a. low
b. high
37. The dominant mode in a rectangular waveguide. c. indeterminate
d. fixed
a. TEM
b. TE 1,1 47. Indicate which of the following cannot be followed by the
c. TE 1,0 word “waveguide”.
d. TM 1,1
a. elliptical
38. The velocity of a resultant wave as it travels through the b. flexible
waveguide. c. coaxial
d. ridged
a. speed of light 48. A piston attenuator is a
b. group velocity
c. phase velocity a. vane attenuator
d. incident velocity b. waveguide below cut-off
c. mode filter
39. The principal mode for a circular waveguide. d. flap attenuator
a. equal to a. almost
b. fully 64. The following are slow wave structures used to retard the
c. slightly RF field in a TWT except
d. electro a. helix
b. attenuator
55. Tuning the ruby maser is done by adjusting the _________ c. waveguide coupled cavity
to alter the energy level of the ferrous chromium. d. NOTA
a. electric field 65. A rectangular waveguide is 5.1 cm by 2.4 cm. The cut-off
b. magnetic field frequency for the dominant mode is
c. pumping of electrons
d. electromagnetic field a. 2.94 GHz
b. 6.25 GHz
56. To overcome the very narrow bandwidth in ruby maser, c. 664 MHz
________ is used. d. 57.7 GHz
57. The following are applications of masers except a. 6.83 cm, 3 cm, 420
b. 3 cm, 6.83 cm, 420
a. radioastronomy c. 6.83 cm, 3.34 cm, 420
b. radiotelescope d. 6.83 cm, 3.34 cm, 338
c. radar
d. ET communications 67. A wave is propagated in a parallel plane waveguide. The
frequency is 6 GHz and the plane separation is 3 cm. The
58. A parametric amplifier is a device which amplifies signal cut-off wavelength for the dominant mode, the group
by varying the and phase velocities are
59. The following are parts of the parametric amplifier except 68. If the MTBF of a communication circuit is 20,000 hours and
its MTTR is 5 hours, what is its unavailability?
a. idling circuit
b. pump circuit a. 0.00025
c. tuned circuit b. 99.975%
d. filter circuit c. 0.25 %
d. 00.975%
60. The number of cavities in a magnetron used in practice.
69. What would be the ERP, in watts if the transmitter output is
a. 4 30 dBm and the transmission line loss is 20 dB and the
b. 6 antenna connected to it has a power gain of 60 dB?
c. 8
d. 10 a. 10,000 watts
b. 1000 watts
61. Changing the anode voltage to change the velocity of c. 100 watts
the electrons in a magnetron tube d. 10 watts
a. TE a. tunnel
b. TM b. gunn
c. H c. IMPATT
d. TEM d. PIN diode
73. Regarded as the oldest semiconductor device
83. A Twystron is a hybrid combination of
a. Shottky Barrier diode
b. PIN diode a. TWT and Magnetron
c. point contact diode b. TWT and Klystron
d. triode c. TWT and Ubitron
d. TWT and gyrotron
74. Also called the hot electron diode
84. A multicavity klystron with interconnected multigap
a. PIN diode cavities
b. ESBAR
c. APD a. TWT
d. Gunn diode b. Twystron
c. EIA
75. Also called tunnel rectifiers d. gyrotron
a. reactance 86. The output from a laser is monochromatic; this means that
b. capacitance it is
c. inductance
d. resistance a. infrared
b. narrow beam
77. Diodes designed to store energy in their capacitance c. polarized
during forward bias and generates harmonics in the d. single frequency
reverse bias.
87. The ruby laser differs from the ruby maser in that the former
a. step recovery
b. gunn a. does not require pumping
c. APD b. needs no resonator
d. IMPATT c. is an oscillator
d. produces much lower powers
78. A cross between the TWT and the magnetron in its
operation 88. The transmission system using two ground planes
a. CFA a. microstrip
b. BWO b. elliptical waveguide
c. EIA c. parallel wire line
d. Twystron d. stripline
79. The following are parts of a multicavity klystron except 89. A BWO is based on the
80. The very first microwave transistors 90. One of the following is unlikely to be used as a pulsed
device
a. GaAs FET
b. Si BJT a. multicavity klystron
c. MIC b. BWO
d. NOTA c. CFA
d. TWT
81. The most common microwave FET which is also known as
the MESFET 91. A microwave tube amplifier uses an axial magnetic field
and a radial electric field
a. Dual GaAs FET
b. Si BJT a. reflex klystron
c. MIC b. coaxial magnetron
d. Schottky Barrier Gate c. TW magnetron
d. CFA
82. It looks like a shorter, thicker TWT 92. The attenuator is used in the TWT to
a. help focusing
b. provide attenuation
c. improve bunching
d. increase gain
a. rat-race
b. E-plane T
c. Hybrid ring
d. Magic T
a. stripline
b. microstrip
c. rectangular waveguide
d. coaxial line