lOMoARcPSD|47762058
111111 compress
Chemistry for Engineers Lecture (Bulacan Polytechnic College)
Scan to open on Studocu
Studocu is not sponsored or endorsed by any college or university
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
PLEASE DO NOT WRITE ANYTHING ON THE QUESTIONNAIRE.
WRITE YOUR SOLUTIONS ON THE ATTACHED SCRATCH PAPER.
DO NOT BRING THIS QUESTIONNAIRE OUTSIDE THE EXAMINATION CENTER.
ALWAYS AIM PERFECT!
1.
How far away is the radio horizon of an antenna 100 ft high?
A. 28.28 mi
C. 20 mi
B. 14.14 mi*
D. 40 mi
Solution:
2. What power density is required to produce electric field strength of 1QQ volts
per meter in air?
A. 13.6 W/m2
C. 16.78 W/m2
B. 18.45 W/m2
D. 26.5 W/m2*
Solution:
3. At a certain time the MUF for transmissions at an angle of incidence of 75° is
17 MHz What is the critical frequency?
A. 2.2 MHz
C. 3.3 MHz
B. 4.4 MHz*
D. 5.5 MHz
Solution:
4. In sky wave propagation what is the critical frequency if Ihe maximum number
of free electrons in a certain ionospheric layer is 1.5 x 1012 per cubic meter?
A. 14 MHz
C. 12 MHz
B. 13 MHz
D. 11 MHz*
Solution:
Page 1 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
5. In wave propagation, determine the refractive index of all ionospheric layer
with 100 x 105 free electrons per cubic meter at 5 MHz frequency.
A. 0.96
C. 0.98
B. 0.97
D. 0.99*
Solution:
6. The total power delivered to the radiator of an isotropic antenna is 200,000 W
Determine the power density at a distance of 100 meters.
A. 1.59 W/m2*
C. 4.67 W/m2
B. 3.69 W/m2
D. 2.12 W/m2
Solution:
7. In a VHF mobile radio system, the base station transmits 100 W at 160 MHz
frequency using half-wave dipole antenna 20 meters above ground. Calculate the
field Strength at the receiving antenna at a height of 4 meters and a distance
of 30 km. (Gain of antenna is 1.64).
A. 25.9 W/m2
C. 41.78 W/m2*
2
B. 13.7 W/m
D. 21.61 W/m2
Solution:
Page 2 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
8. What is the effective radiated power (ERP) of a repeater with 450W
transmitting power output, 4 dB feedline loss, 6 dB duplexer loss, 7 dB
circulator loss and feed line antenna gain of 25 dB?
A. 1678.12 W
C. 2839.31 W*
B. 2434.34 W
D. 2134.61 W
Solution:
9. What is the index of refraction of a certain substance if a light travel
through the substance at 100 meters at a time is to 140 meters to air?
A. 1.1
C. 1.3
B. 1.2
D. 1.4*
Solution:
10. Determine the effective radiated power of 20 kW TV broadcast transmitter whose
antenna has a field gain of 2
A. 40 kW
C. 30 kW
B. 80 kW*
D. 60 kW
Solution:
Page 3 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
11. What is the free space loss, in dB, between two microwave parabolic antennas
38.0 kilometer apart operating at 7.0 GHz?
A. 140.89 dB*
C. 220.4 dB
B. 70.23 dB
D. 130.45 dB
Solution:
12. In skywave propagation, if the critical frequency is 25 MHz what is the best
frequency to use? Assume radiation angle of 45o.
A. 30 MHz*
C. 40 MHz
B. 35 MHz
D. 45 MHz
Solution:
13. If the velocity of propagation in a certain medium is 200 x l06, what is its
refractive index?
A. 1
C. 1.5*
B. 1.25
D. 2
Solution:
Page 4 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
14. What is the propagation velocity of a signal in a transmission line whose
inductance and capacitance are 5 uH/m and 20 uF/m respectively?
A. 100 x103*
C. 300 x103
B. 200 x103
D. 400 x103
Solution:
15. A certain earth station transmitter output power is 10 kW, transmitting
antenna gain 100 dBi, receiving antenna gain 75 dB; uplink and downlink
frequency of 2.4 GHz and 2 GHz respectively What is the received signal level
at the satellite?
A. 6.21uW
C. 7.71 uW*
B. 7.71 mW
D. 6.21 mW
Solution:
16. A mobile radio system base station is installed 50 meters above the ground and
transmits 150 W at 54 MHz. If the transmitting antenna gain is 5.17, how far
will the receiving antenna be, if the antenna height is 30 m and the received
field strength is 22 uV/m.
A. 130,456 m
C. 120,456 m
B. 110,156 m
D. 153,313 m*
Solution:
Page 5 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
17. The antenna is beam 30o above the ground for optimum transmission, Determine
the transmission range, if ionospheric transmission is used and virtual height
is 200 km. Assuming, the earth is flat.
A. 699 km
C. 671 km
B. 570 km
D. 693 km*
Solution:
18. A microwave radio link is installed on a hill 100 m high above the ground. The link is 10 km
from the ground station, is set to transmit 10 W from a parabolic dish having a gain of 3000
over isotropic. Calculate the signal strength received if the height of the ground station is 10
m operating frequency at 250 MHz.
A. 89.76 mV/m
B. 102.34 mV/m
Solution:
C. 98.12 mV/m
D. 99.34 mV/m*
19. An unknown medium was used in communication system if the characteristic,
impedance of that medium is 150 ohms, what is the relative permittivity?
A. 2.12
C. 4.86
B. 2.51*
D. 3.33
Solution:
Page 6 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
20. What is the angle of incidence of the radio wave signal at as it moves from air to glass, if the
angle of refraction is 8.2o?
A. 1.19 o
B. 2.81 o
C. 2.93 o *
D. 1.56 o
Solution:
21. A dish designed for operation at 150 MHz is operated at twice that frequency.
By what factor do gain change?
A. doubled
C. increased 2 times
B. halved
D. increased 4 times
Solution:
22. What is the power gain in dB of a uniformly illuminated parabolic refiector
whose half-power beamwidth is 3 degrees?
A. 34.71 dB
C. 33.5 dB
B. 35.44 dB
D. 31.22 dB
23. In aperture antennas for microwave communications what is the aperture number
if the angular aperture is 55 o?
A. 34.71 dB
C. 33.5 dB
B. 35.44 dB
D. 31.22 dB
Solution:
Page 7 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
24. What is the effective area of a Hertzian dipole antenna for unity efficiency at 3 MHz?
A. 1190 m2 *
C. 2581 m2
B. 2182 m2
D. 1245 m2
Solution:
25. A certain antenna has a gain of 7 dB with respect to an isotropic radiator.
What is the effective area if it operates at 200 MHz?
A. 0.699 m2
C. 0.567 m2
2
B. 0.897 m *
D. 0.671 m2
Solution:
26. Determine the gain of an antenna with respect to a dipofe if its gain with
respect to isotropic is 50 dBi.
A. 34.56 dB
C. 88.25 dB
B. 47.86 dB
D. 44.78 dB
Solution:
Page 8 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
27. If an antenna has a length of 0.125 λ then what is the radiation resistance?
A. 12.56
C. 13.55 dB
B. 12.34*
D. 15.78 dB
Solution:
28. A helical antenna has the following dimensions: pitch is 1/3 wavelength, diameter is 1/4
wavelength and turns is 27. What is the gain In dB?
A. 19.2 dB*
B. 20.01 dB
Solution:
C. 22.3 dB
D. 34.2 dB
29. What is the phase separation of two antennas 3/8 wavelengths apart?
A. 132o
C. 99.89o
B. 135o*
D. 34.76o
Solution:
30. A 400 feet antenna is to be operated at 6,200 KHz. What is the wavelength at this frequency?
A. 48.4 m*
C. 25.78 m
B. 38.45 m
D. 57.89 m
31. A TVRO installation for use with a C-band satellite (download frequency at 4
GHz); has a diameter of about 3.5 meters and an efficiency of 60% Calculate
its beamwidth.
A. 3 degrees
C. 2.5 degrees
B. 1.5 degrees*
D. 2.75 degrees
Solution:
Page 9 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
32. A 500 kHz antenna radiates 500 W of power The same antenna provides a field strength equal to
1.5 mV/m. If the power delivered by the antenna is increased to 1 kW, what would be the expected
field intensity?
A. increases twice
B. increases by sqrt of two*
C. increases by half
D. decreases by two
Solution:
33. What is the effective radiated power (ERP) of a repeater with 250 W transmitting power output, 3
dB feed line loss, 4 dB duplexer loss, 5 dB circulator loss and feedline antenna gain of 20 dB?
A. 1223.67 W
B. 1577.61 W*
C. 1234.77 W
D. 1556.88 W
Solution:
34. If the antenna current increases 3.4 times, how much does the radiated power increase?
A. decreases by 6 times
C. decreases by 12 times
B. increases by 6 times
D. increases by 12 times*
Solution:
Page 10 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
35. Determine the effective radiated power of an FM transmitter if the input power
to the final amplifier is 370 W with 60% efficiency if the field gain of the
antenna is 1.3, assuming 100% transmission line efficiency.
A. 375.2 W*
C. 456.6 W
B. 234.6 W
D. 332.12 W
Solution:
36. A dipole antenna requires to be feed with 20 kW of power to produce a given
signal strength to a particular distant point. If the addition or a reflector
makes the same field strength available with an input power of 11 kW. What is
the gain in dB obtained by the use of the reflector? (Gain referred to this
particular dipole).
A. 1.5 dB
C. 3.3 dB
B. 2.6 dB*
D. 4.2 dB
Solution:
37. The frequency of operation of a dipole antenna cut to length of 3.4 m.
A. 1.5 dB
C. 3.3 dB
B. 2.6 dB*
D. 4.2 dB
Solution:
Page 11 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
38. What is the ohmic resistance of the antenna, if the efficiency of the antenna
is 0.96 and the radiation resistance is 72 ohms.
A. 1 ohms
C. 3 ohms
B. 2 ohms*
D. 4 ohms
Solution:
39. What is the gain of
efficiency of 92 %?
A. 1.48
B. 1.51*
Solution:
a
half-wave
dipole
antenna
if
the
antenna
has
an
C. 3.2
D. 2.2
40. A satellite tracking device uses a helical antenna that is operating at 1.2
GHz. If the optimum diameter of the antenna is 8 cm and 10 turns, what is the
gain of the antenna?
A. 15.78 dB*
C. 22.13 dB
B. 30.34 dB
D. 11.34 dB
Solution:
15N/4
41. A parabolic antenna used in the satellite earth station has beamwidth of 3 o
What is the gain of the antenna if the antenna efficiency is 85%?
A. 3456
C. 3476
B. 4567*
D. 1134
Solution:
Page 12 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
42. A Yagi antenna with front-to-back ratio of 10 dB radiates power of 10 watts in
the opposite direction. Determine the power output of the transmitter, if the
gain of the antenna Is 10 dBi (assume lossless transmission line and perfectly
matched.
A. 30 W
C. 10 W*
B. 20 W
D. 5 W
Solution:
43. For a multimode step-index fiber wilh glass core (n 1=1.53) and a fused quartz
cladding (n2=1.44) determine 1he critical angle.
A. 30.35o
C. 38.37 o
o
B. 70.25 *
D. 35.45 o
Solution:
Page 13 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
44. For a glass (n=1.55) to ethyl alcohol (n= 1.36) interface, and an angle of
incidence or 33 degrees, determine the angle of refraction.
A. 30.35o
C. 38.37 o*
B. 70.25o
D. 35.45 o
Solution:
45. What minimum bandwidth is required to pass a pulse train without distortion if
its rise time is 6 ns?
A. 55.33 MHz*
C. 38.37 MHz
B. 33.55 MHz
D. 35.45 MHz
Solution:
46. What is the fastest rise time that
faithfully if the bandwidth is 200 kHz?
A. 4.75 us
B. 2.24 us
Solution:
a
circuit
will
C. 1.75 us*
D. 3.45 us
Page 14 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
pass
a
pulse
train
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
47. The input square wave to an oscilloscope has a rise lime of 15 ns. What is the
rise time of the displayed square wave if the bandwidth of the oscilloscope is
60 MHz?
A. 47. 5 ns
C. 13.4 ns
B. 17.7 ns*
D. 15.67 ns
Solution:
48. What is the maximum permissible value for the pulse-spreading constant of 65
km length fiber that must not lengthen the pulses by more than 200 ns?
A. 30.8 ns/km
C. 4.18 ns/km
B. 27.7 ns/km
D. 3.08 ns/km*
Solution:
49. An optic fiber is made of glass with a surface index of 1.55 and is clad with
another glass with a refractive Index of 1.51. Launching, takes place on air.
Determine the numerical aperture of the fiber
A. 0.30
C. 0.55
B. 0.35*
D. 0.61
Page 15 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
50. What is the number of modes
normalized frequency is 10?
A. 30 modes
B. 50 modes*
Solution:
that
an
optical
fiber
can
support
if
the
C. 80 modes
D. 100 modes
51. Calculate the energy of the photon of infrared light energy at 1.55 um.
A. 1.28 x10-19 J*
C. 3.44 x10-19 J
-19
B. 2.38 x10
J
D. 4.48 x10-19 J
Solution:
52.
If a fiber optic system has a rise lime of 16 ns, the soiree rise time is
1.5 ns and the detector rise time is 2 ns, what is the cable rise time?
A. 12.3 ns
C. 15.3 ns
B. 14 ns*
D. 18.3 ns
Solution:
Page 16 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
53. An optical fiber is designed to give a numerical aperture of 0.25. what is the
fractional difference between the core and The cladding if the liber is made
of glass with refractive index of 1.51?
A. .0123
C. .0212
B. .0137*
D. .2345
Solution:
54. A fiber glass has a core diameter of 60 um and numerical aperture of 0.235
What is its V-number if the fiber is operates with light source wavelength of
0.735 um?
A. 60.1
C. 60.3
B. 60.2
D. 60.4*
55. 20 angstroms is equal to how many microns?
A. 0.002 micron*
B. 0.02 micron
C. 0.0016 micron
D. 0.0044 micron
56. What is the uplink receiver frequency if the downlink transmitter is on channel 4 {3.64 GHz)?
A. 6.1 GHz*
C. 3.3 GHz
B. 7.12 GHz
D. 2.1 GHz
Page 17 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
57. Find the orbital period of a satellite in a circular orbit 600 km above the
surface of the earth
A. 61 hours
C. 3 hours
B. 1.6 hours*
D. 2 hours
Solution:
58. At what height is the satellite from the earth's surface if its sidereal
period is 18 hours?
A. 28486 km*
B. 34567 km
C. 2345 km
D. 23411 km
Page 18 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
59. Materials generally preferred for waveguides are
a. Brass and aluminum*
c. Non-metallic solids
b. Cast iron and steel
d. High carbon steel and vanadian steel
60. Waveguide feeders are pressurized to
a. Reduce loss
c. Detect faults
b. Reduce noise
d. Prevent ingress of moisture*
61. The output of a LASER is monochromatic; this means that it is
a. Infrared
c. Polarized
b. Narrow beam
d. Single frequency*
62.
What do you call the process of speeding up and slowing down the beam of
electrons in the vacuum tube?
a. Velocity modulation*
c. Gyrofrequency
b. Logitudinal velocity
d. Group frequency
63. For a microwave transistor to operate at the highest frequencies, the
(indicate the false answer)
A. collector voltage must be large C. base should be thin
B. collector current must be high
D. emitter area must be large *
64. A varactor diode may be useful at microwave frequencies (indicate the false
answer)
A. for electronic tuning
C. as an oscillator *
B. for frequency multiplication D. as a parametric amplifier
65. If high-order frequency multiplication is required from a diode multiplier,
A. the resistive cutoff frequency must be high
B. a small value of the base resistance is required
C. a step-recovery diode must be used *
D. a large range of capacitance variation is needed
66. A parametric amplifier has an input and output frequency of 2.25 GHz, and is
pumped at 4.5 GHz. It is
A. traveling-wave amplifier
B. degenerative amplifier *
C. lower-sideband up-converter
D. upper-sideband up-converter
67. A non-degenerate parametric amplifier has an input frequency fi and a pump
frequency fp. The idler frequency is
A. fi
B. 2fi
C. fi– fp
D. fp – fi *
68. Traveling-wave parametric amplifiers are used to
A. provide a greater gain
B. reduce the number of varactor diodes required
C. avoid the need for cooling
D. provide greater bandwidth *
69. A parametric amplifier sometimes uses a circulator to
A. prevent noise feedback *
B. allow the antenna to be used simultaneously for transmission and reception
C. separate the signal and idler frequencies
D. permit more efficient pumping
70. The nondegenerate one-port parametric amplifier should have a high ratio of
pump to signal frequency because this
A. permits satisfactory high frequency operation
B. yields a low noise figure *
C. reduce the pump power required
D. permits satisfactory low frequency operation
71. The wavelength of a wave in a waveguide
A. is greater than of free space *
B. depends only on the waveguide dimensions and the free-space wavelength
Page 19 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
C. is inversely proportional to the phase velocity
D. is directly proportional to the group velocity
72. The main difference between the operation of transmission lines and waveguides
is that
A. the latter are not distributed, like transmission lines
B. the former can use stubs and quarter-wave transformers, unlike the latter
C. transmission lines use the principal mode of propagation, and therefore do
not suffer from low-frequency cut-off *
D. terms such as impedance matching and standing-wave ratio cannot be applied
to waveguides
73. Compared with equivalent transmission lines, 3-GHz waveguides (indicate false
statement)
A. are less lossy
C. are less bulky *
B. can carry higher powers
D. have lower attenuation
74. When a particular mode is excited in a waveguide, there appears an extra
electric component, in the direction of propagation. The resulting mode is
A. transverse-electric
C. longitudinal
B. transverse-magnetic * D. transverse-electromagnetic
75. When electromagnetic waves are reflected at an angle from a wall, their
wavelength along the wall is
A. the same as in free space
B. the same as the wavelength perpendicular to the wall
C. shortened because of Doppler effect
D. greater than in the actual direction of propagation *
76. As a result of reflections from a plane conducting wall, electromagnetic waves
acquire an apparent velocity greater than the velocity of light in space. This
is called the
A. velocity of propagation
C. group velocity
77. Indicate the false statement. When the free space wavelength of a signal
equals the cut-off wavelength of the guide
A. the group velocity of the signal becomes zero
B. the phase velocity of the signal becomes infinite
C. the characteristic impedance of the guide becomes infinite *
D. the wavelength within the waveguide becomes infinite
78. A directional coupler with three or more holes is sometimes used in preference
to the two-hole coupler
A. because it is more efficient
B. to increase coupling of the signal
C. to reduce spurious mode generation
79. A ferrite is
A. a nonconductor with magnetic properties *
B. an inter-metallic compound with particularly good conductivity
C. an insulator which heavily attenuates magnetic fields
D. a microwave semiconductor invented by Faraday
80. The maximum power that may be handled by a ferrite component is limited by the
A. Curie temperature *
C. line width
B. Saturation magnetization
D. gyromagnetic resonance
81. A PIN diode is
A. a metal semiconductor point-contact diode
B. a microwave mixer diode
C. often used as a microwave detector
D. suitable for use as a microwave switch *
82. A duplexer is used
A. to couple two different antennas to a transmitter without mutual
interference
Page 20 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
B. to allow one antenna to be used for reception or retransmission without
mutual interference *
C. to prevent interference between two antennas when they are connected to a
receiver
D. to increase the speed of the pulses in pulses in pulsed radar
83. For some applications, circular waveguides may be preferred to rectangular
ones because of
A. the smaller cross section needed at any frequency
B. lower attenuation *
C. freedom from spurious modes
D. rotation of polarization
84. Indicate which of the following cannot be followed by the word
“waveguide”:
A. Elliptical
B. Flexible C. Coaxial * D. Ridged
85. In order to reduce cross-sectional dimensions, the waveguide to use is
A. circular B. ridged * C. rectangular D. flexible
210.
For handling high powers, the best transmission medium is
A. stripline
C. rectangular waveguide *
B. microstrip
D. coaxial line
86. The system using two ground planes is
A. microstrip
C. parallel-wire line
B. horn antenna
D. stripline *
87. Indicate the false statement, an advantage of stripline over microstrip is its
A. easier integration with semiconductor devices*
B. lower tendency to radiate
C. higher isolation between adjacent circuits
D. higher Q
88. Indicate the false statement. An advantage of stripline over waveguides is its
A. smaller bulk
B. greater bandwidth
C. higher power handling capacity*
D. greater compatibility with semiconductor devices
89. A disadvantage of optical fibers as compared with waveguides is
A. that they are new technology*
B. their inadequate channel capacity
C. the high crosstalk from which they suffer
D. that magnetic fields affect them too easily
90.
A microwave tube amplifier uses an axial magnetic field and a radial
electric field. This is the
A. reflex klystron
B. coaxial magnetron
C. traveling-wave magnetron
D. CFA *
91. One of the reasons why vacuum tubes eventually fail at microwave frequencies
is that their
A. noise figure increases *
B. transit time becomes too short
C. shunt capacitive reactances become too large
D. series inductive reactances become too small
92. Indicate the false statement. Transit time in microwave tubes will be reduced
if
A. the electrodes are brought closer together
B. a higher anode current is used
C. multiple or coaxial leads are used *
Page 21 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
D. the anode voltage is made larger
93. The multicavity klystron
A. is not a good low-level amplifier because of noise *
B. has a higher repeller voltage to ensure a rapid transit time
C. is not suitable for pulsed operation
D. needs a long transit time through the buncher cavity to ensure current
modulation
94. Indicate the false statement. Klystron amplifiers may use intermediate
cavities to
A. prevent the oscillations that occur in two-cavity klystrons *
B. increase the bandwidth of the device
C. improve the power gain
D. increase the efficiency of the klystron
95. The TWT is sometimes preferred to the multicavity klystron amplifier, because
it
A. is more efficient
B. has a greater bandwidth *
C. has a higher number of modes
D. produces a higher output power
96. The transit time in the repeller space of a reflex klystron must be n + 3/4
cycles to ensure that
A. electrons are accelerated by the gap voltage on their return
B. returning electrons give energy to the gap oscillations *
C. it is equal to the period of the cavity oscillations
D. the repeller is not damaged by striking electrons
97. The modes in a reflex klystron
A. results from excessive transit time across the resonator gap
B. correspond to different oscillating frequencies of the cavity
C. are caused by spurious frequency modulation
D. all give much the same frequency but different transit times*
223.
To protect the repeller of a klystron (indicate the false statement)
A. a permanent negative voltage is connected to the cathode*
B. the repeller voltage is applied before the anode voltage
C. are caused by spurious frequency modulation
D. a cathode resistor is often used
98. The cavity magnetron uses strapping to
A. prevent mode jumping *
B. prevent cathode back-heating
C. ensure bunching
D. improve the phase-focusing effect
99. Periodic permanent-magnet focusing is used with TWTs to
A. allow pulsed operation
B. improve electron bunching
C. avoid the bulk of an electromagnet *
D. allow coupled-cavity operation at the highest frequencies
100.
Indicate the false statement. FETs are preferred to bipolar transistors at
the highest frequencies because they
A. are less noisy
B. lend themselves more easily to integration *
C. are capable of higher efficiencies
D. can provide higher gains
Page 22 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)
lOMoARcPSD|47762058
RES EST-2
MANILA  CEBU  BACOLOD  DAVAO
RES-ST1: WavePro and Antennas, Microwave, Sat.Comm., Fiber Optics
ALWAYS AIM PERFECT PERCians!
REVIEW YOUR ANSWERS
Page 23 of 7
Downloaded by firstwinner AUS (xolah13815@hraifi.com)