Radio Wave Propagation MCQs
Radio Wave Propagation MCQs
Radio Wave Propagation MCQs
a. receive voltage
b. magnetic induction
c. field strength
d. power density
a. F1
b. F2
c. E
d. D
c. Christian Huygens
d. Appleton Layers
a. band
b. bandwidth
c. channel
d. group
a. 180 degrees
b. 90 degrees
c. 270 degrees
d. 45 degrees
a. a magnetic field
b. sound field
c. electromagnetic waves
a. ground waves
b. sky waves
c. surface waves
d. space waves
a. is caused by reflection
a. ionosphere
b. stratosphere
c. troposphere
d. ozone layer
a. F2
b. F1
c. D
d. E
a. index of refraction
b. K factor
c. Fresnel zone
d. path profile
a. atmospheric-multipath
b. Fresnel zone
c. reflection-multipath
d. Rayleigh fading
16. The layer that reflects very low frequency waves and absorbs medium
frequency waves.
a. D Layer
b. E Layer
c. F1 Layer
d. F2 Layer
a. D Layer
b. E Layer
c. F1 Layer
d. F2 Layer
18. What is the highest frequency that can be sent straight upward and be
returned to earth?
a. MUF
b. skip frequency
c. critical frequency
d. gyro frequency
a. 0.3 to 3MHz
b. 3 to 30MHz
c. 30 to 300MHz
d. 3to 30MHz
b. 0.03 to 0.3MHz
c. 0.3 to 3MHz
d. 3 to 30 MHz
a. scatter angle
b. take-off angle
c. antenna size
d. the troposphere
a. polarization
b. directivity
c. radiation
d. ERP
a. vertically polarized
b. omnidirectional
c. horizontally polarized
d. circularly polarized
a. 300x106 m/s
b. 300x106 km/s
c. 186,000 km/s
d. 186,000 m/s
28. What is the effective radiated power of a repeater with 200W transmitter
power output, 4dB feed line loss, 4dB duplexer and circulator loss, and 10dB
feed line antenna gain?
a. 2000 W
b. 126 W
c. 317 W
d. 260 W
a. Plane wave
b. isotropic wave
c. vertical wave
d. horizontal wave
d. is a universal constant
b may seem less or more than its actual depth, depending on the
object
d. may seem less or more than its actual depth, depending on the
transparent liquid
b. a current in a conductor
34. VHF ship station transmitters must have the capability of reducing carrier
power to
a. 1 W
b. 10 W
c. 25 W
d. 50 W
35. Most of the effects an electro magnetic wave produces when it interacts
with matter are due to its
a. magnetic field
b. speed
c. frequency
d. electric field
a. atmospheric absorption
b. tropospheric scatter
c. sporadic E
37. When the electric field is perpendicular in the surface of the earth, what
is the polarization of the TEM wave?
a. elliptical
b. vertical
c. horizontal
d. circular
38. When the magnetic field is perpendicular to the surface of the earth,
what is the polarization of the TEM wave?
a. circular
b. horizontal
c. vertical
d. elliptical
39. When the magnetic field is parallel to the surface of the earth, what is
the polarization of the TEM wave?
a. elliptical
b. horizontal
c. vertical
d. circular
41. How does the bandwidth of the transmitted signal affect selective fading?
b. SITOR
a. sound field
b. magnetic field
c. electric field
d. nothing in particular
44. When a space-wave signal passes over a mountain ridge, a small part of
the signal is diffracted down the far side of the mountain. This phenomenon
is called
a. discontinuity scattering
b. troposheric ducting
c. knife-edge diffraction
d. space-wave refraction
a. is greater than 1
b. is less than 1
c. is equal to 1
47. What is the effective earth radius when surface refractivity, and N equals
300?
a. 6370 km
b.7270 km
c.7950 km
d. 8500 km
a. 1.23
b. 1.29
c. 1.33
d. 1.32
49. Electric field that lies in a plane perpendicular to the earths surface
a. vertical polarization
b. horizontal polarization
c. circular polarization
d. elliptical polarization
50. Electric field that lies in a plane parallel to the earths surface
a. vertical polarization
b. horizontal polarization
c. circular polarization
d. elliptical polarization
a. SIDs
b. fading
c. atmospheric storms
d. faraday rotation
52. VLF waves are used for some types of services because
53. Indicate which of the following frequencies cannot be used for reliable
beyond-the-horizon terrestrial communications without repeaters
a. 20 KHz
b. 15 MHz
c. 900 MHz
d. 12 GHz
55. Distances near the skip distance should be used for sky-wave
propagation
a. to avoid tilting
b. a broadband antenna
c. frequency diversity
d. space diversity
a. window
b. critical frequency
a. ground waves.
b. sky waves
c. surface waves
d. space waves
a. HF
b. VHF
c. UHF
d. VLF
60. The ground wave eventually disappears as one moves away from the
transmitter because of
d. tilting
c. ionization
62. an electromagnetic waves travel in free space, only one of the following
can happen to them.
a. absorption
b. attenuation
c. refraction
d. reflection
a. their frequency
a. X-rays
b. Radio waves
c. Ultraviolet rays
d. Radar waves
a. Wavelength
b. Charge
c. Frequency
d. Energy
68. The ionosphere is a region of ionized gas in the upper atmosphere. The
ionosphere is responsible for
b. Rainbows
69. Light of which the following colors has the shortest wavelength
a. Red
b. Yellow
c. Blue
d. Green
a. Amplitude
b. Resonance
c. Waveform
d. Pitch
a. Are erect
c. Are inverted
72. When a beam of light enters one medium from another, a quality that
never changes is its
a. Direction
b. Frequency
c. Speed
d. Wavelength
a. Is smaller
b. Is larger
c. Is the same
d. Either A or B above
74. A light ray enters one medium from another along the normal. The angle
of refraction is
a. 0
b. 90 degrees
75. What layer aids MF surface-wave propagation a little and reflects some
HF waves in daytime?
a. E layer
b. D layer
c. F1 layer
d. F2 layer
c. May seems more than its actual depth, depending on the index of
refraction of the liquid
d. May seem less or more than its actual depth depending on the angle
of view
78. Total internal reflection can occur when light passes from one medium to
another
79. When the light ray approaches a glass-air interface from the glass side at
the critical angle, the angle of refraction is
a. 0
b. 90 degrees
c. 45 degrees
80. The brightness of light source is called its luminous intensity , whose unit
is
a. Candela
b. Lux
c. Lumen
d. Footcandle
d. Fluorescent tube
a. 8000 cd
b. 8000 lx
c. 8000 lm
d. 800 W
83. Light enters a glass plate whose index of refraction is 1.6 at an angle of
incidence of 30 degrees . the angle of refraction is
a. 18 degrees
b. 48 degrees
c. 19 degrees
d. 53 degrees
a. 0 degrees
b. 45 degrees
c. 30 degrees
d. 90 degrees
a. 0.625
b. 1.52
c. 0.66
d. 1.6
a. 0.67
b. 1.3
c. 0.74
d. 1.5
87. The critical angle of incidence for light going from crown glass (n=1.5) to
ice (n=1.3) is
a. 12 degrees
b. 50 degrees
c. 42 degrees
d. 60 degrees
a. /2 sr
b. 2 sr
c. sr
a. 9.6 lx
b. 377 lx
c. 120 lx
d. 1508 lx
a. Direct wave
b. Sky wave
c. Surface wave
d. Standing wave
a. Diffused
b. Absorbed
c. Refracted
d. Reflected
b. 3 to 30 MHz
c. 30 to 300 MHz
93. The ionosphere has its greatest effect on signals in what frequency
range?
b. 3 to 30 MHz
c. 30 to 300 MHz
94. The type of radio wave responsible for long distance communications by
multiple skips is the
a. Ground wave
b. Direct wave
c. Surface wave
d. Sky wave
a. VHF
b. UHF
c. HF
d. Microwave
a. 20 mi
b. 33.2 mi
c. 38.7 mi
d. 53.2 mi
98. States that power density is inversely proportional to the distance from
its source.
a. Principle of reciprocity
c. Huygens Princple
d. Faradays law
a. Space wave
b. Sky wave
c. Surface wave
d. Satellite wave
a. F1
b. D
c. F2
d. E
a. D
b. E
c. F1
d. F2
a. Sun spot
b. Cosmic rays
c. Galactic disturbance
d. Ultraviolet radiation
a. D
b. E
c. F1
d. F2
a. ELF
b. VLF
c. MF
d. All of these
105. The ability of the ionosphere to reflect a radio wave back to the earth is
determined by
a. Operating frequency
b. Ion density
c. Angle of incidence
d. All of these
106. Highest frequency that can be used for sky wave propagation between
two given points on earth.
a. Critical frequency
b. MUF
d. UHF
107. The shortest distance measured along the earths surface that a sky
wave is returned to earth.
a. MUF
b. Quarter-wavelength
c. Skip distance
d. Skip zone
a. Interference
b. Fading
c. Tracking
d. Variable frequency
a. Space diversity
b. Frequency diversity
c. Hybrid diversity
d. Polarization diversity
a. Space diversity
b. Frequency diversity
c. Hybrid diversity
d. Polarization diversity
d. Diversity
112. What do you call the gigantic emissions of hydrogen from the sun?
a. Solar flares
b. SIDs
c. Kennely-Heaviside
d. Sun spots
a. Solar flares
b. SIDs
c. Sun spots
d. Intertropical convergence
a. Microwave propagation
c. Troposcatter propagation
115. Two directional antennas are pointed so that their beams intersect in
the troposphere.
a. Skywave
b. Surface wave
c. Microwave
d. Troposcatter
a. Ducting
b. Trposcatter
c. Skywave
d. Space wave
a. Troposphere
b. SID
c. Duct
d. Huygens principle
a. Electric field
b. Magnetic field
c. Gyro
d. Direction of propagation
a. Skip distance
b. Maximum usable
c. Shadow zone
d. Twilight zone
a. Senlls law
b. Huygens principle
c. Rayleighs principle
d. De Morgans theorem
a. Stratosphere
b. Troposphere
c. Ionosphere
d. Ozone layer
a. At midday
b. At midnight
c. At duck
d. At dawn
a. Night time
c. Noontime
d. Morning
b. High frequencies
c. Medium frequency
d. Low frequency
a. D layer
b. E layer
c. F1 layer
d. F2 layer
a. slide
b. door
c. window
d. frame
a. critical angle
b. scatter angle
c. backscatter angle
d. sidescatter angle
a. duplexer
b. diplexer
c. isolator
d. circulator
a. fading
b. faraday effect
c. ghosting
d. multipath fading
130. A diversity scheme wherein the receiver receives two fading signals
from two different directions.
a. frequency diversity
b. time diversity
c. angle diversity
d. space diversity
131. The radio wavelength known as _________ falls within the medium
frequency range.
a. centimetric wave
b. decametric wave
c. hectometric wave
d. myriametric wave
a. E
b. F1
c. F2
d. D
133. The frequency band used as sub-carriers, or signals which carry the
baseband modulating information but in turn modulate another higherfrequency carrier is _________.
a. LF
b. MF
c. VLF
d. VH
134. The range of frequency band termed as super high frequency (SHF) is
within _________.
a. 30 300 GHz
b. 30 300 MHz
c. 3 30 GHz
135. Electric field that lies in a plane perpendicular to the earths surface.
a. circular polarization
b. vertical polarization
c. horizontal polarization
d. elliptical polarization
a. is vertical
b. is horizontal
c. is circular
137. The surface wave is effective only at frequencies below about _________
MHz.
a. 30
b. 3
c. 300
d. 0.3
a. space
b. sky
c. ground
d. direct
a. increases
b. decreases
d. not a factor
a. long
b. short
c. medium
d. millimeter
a. phase difference
b. topographic variation
c. climate
d. ionosphere variation
a. sky
b. space
c. direct
d. ground
c. to create diversity
b. HF and VHF
a. desert
b. water
c. forest
d. mountain
a. static
b. magnetic
c. direction
d. propagation
a. horizontal
b. parallel
c. transverse
d. vertical
a. D-layer absorption
b. Faraday rotation
c. Tropospheric ducting
d. Moonbounce
152. How does the bandwidth of the transmitted signal affect selective
fading?
153. How much farther does the radio-path horizon distance exceed the
geometric horizon?
a. -6
b. -3
c. 6
d. 3
a. 5 miles
b. 15 miles
c. 30 miles
d. 100 miles
158. A 500 kHz radiates 500 W of power. The same antenna produces a field
strength equal 10 1.5 mV/, If the power delivered by the antenna is increased
to 1 kW, what would be the expected field intensity?
a. 3 mV/m
b. 1.732 mV/m
c. 2.12 mV/m
d. 1.456 mV/m
a. F1 layer
b. E layer
c. F2 layer
d. D layer
160. What happens to a radio wave as it travels in space and collides with
other particles
c. Aurora is created
a. 163.9 ohms
b. 377 ohms
c. 243 ohms
d. 250 ohms
a. 190 mV/m
b. 95.49 uV/m
c. 0.189 W/m
d. 13.416 V/m
a. 1.183
b. 1.4
c. 0.714
d. 0.845
167. Why does the radio path horizon distance exceed the geometric
horizon?
a. E-layer skip
b. D-layer skip
c. Auroral skip
a. 40 kW
b. 80 kW
c. 20 kW
d. 10 kW
a. 4936.8 kHz
b. 5775 kHz
c. 4044 kHz
d. 4908.75 kHz
171. What is the propagation effect called when phase difference between
radio wave components of the same transmission are experiences at the
recovery station?
a. Faradays rotation
b. Diversity reception
c. Selective fading
d. Phase shift
a. Morning
b. Noon
173. The dielectric strength of a certain medium is about 2.85 MV/m. what is
the maximum power density of an electromagnetic wave in this medium?
175. 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/sq m
b. 24.49 W/sq m
c. 3.18 W/sq m
d. 244.95 W/sq m
176. The bending of radio waves passing over the top of a mountain range
disperse a weak portion of the signal behind the mountain is
b. Knife-edge diffraction
c. Shadowing
177. A radio wave moves from air (er=1) to glass (er=7.8). Its angle of
incidence is 20 degrees. What is the angle of refraction?
a. 7 degrees
b. 29 degrees
c. 10.3 degrees
d. 72.79 degrees
a. -2.6 dB
b. 2.6 dB
c. 5.19 dB
d. -5.19 dB
181. An automobile travels at 90 km/h, find the time between fades if the car
uses a cellphone at 800 MHz
a. 11.2 ms
b. 15 ms
c. 7.5 ms
d. 4.7 ms
182. When the electric field is parallel to the surface of the earth, what is the
polarization of the electromagnetic wave?
a. Vertical
b. Horizontal
c. Circular
d. Elliptical
a. 51.355 MHz
b. 17.118 MHz
c. 34.237 MHz
d. 5.706 MHz
186. When the electric field is perpendicular to the surface of the earth, what
is the polarization of the electromagnetic wave?
a. Circular
b. Vertical
c. Horizontal
d. Elliptical
a. 0.999
b. 0.936
c. 0.956
d. 0.987
a. 404 nW
b. 2.04 nW
c. 960 nW
d. 680 nW
191. What is the frequency to use for skywave propagation if the critical
frequency is 15 MHZ and the angle of radiation is 60 degrees?
a. 17.32 MHz
b. 30 MHz
c. 25.5 MHz
d. 14.722 MHz
192. When the magnetic field is parallel tot eh surface of the earth, what is
the polarization of the electromagnetic field?
a. Circular
b. Horizontal
c. Elliptical
d. Vertical
a. 0.509
b. 0.631
c. 0.713
d. 1.965
194. When the magnetic field is perpendicular to the surface of the earth,
what is the polarization of the electromagnetic field?
a. Circular
b. Horizontal
c. Elliptical
d. Vertical
b. High frequencies
a. Diffused
b. Absorbed
c. Refracted
d. Reflected
a. Transceiver
b. Remitter
c. Repeater
d. Amplifier
199. A taxi company uses a central dispatcher with an antenna at the top of
a 25 m tower, to communicate with the taxicabs. The taxi antennas are on
the roofs of the cars, approximately 1.5 m above the ground. Calculate the
maximum communication distance between the dispatcher and a taxi.
a. 25.7 km
b. 8.8 km
c. 21 km
d. 10.1
a. Direct wave
b. Sky wave
c. Surface wave
d. Standing wave
201. The cumulative sum of the direct, ground-reflected, and surface waves
is reflected to as _________.
a. Space wave
b. Ground wave
c. Sky wave
d. Direct waves
a. MF and HF
b. VLF and MF
c. MF and VHF
d. VLF and LF
a. polarization diversity
c. time diversity
d. frequency diversity
b. Ground waves are limited to very low, low and medium frequencies
requiring large antennas
d. Any of these
a. window
b. critical frequency
206. It is simply the orientation of the electric field vector in respect to the
surface of the Earth
a. Polarization
b. Wavefront
c. Rays
d. Power density
a. 1.99 W/m^2
b. 7.96 W/m^2
c. 3.22 W/m^2
d. 9.17 W/m^2
208. The ground wave eventually disappears, as moves away from the
transmitter, because of
d. tilting
209. If the electric field is propagating parallel to the surface of the Earth, the
polarization is _________.
a. Circular
b. Vertical
c. Horizontal
d. Elliptical
210. A taxi company uses a central dispatcher, with an antenna at the top of
a 15m tower, to communicate with taxi cabs. The taxi antennas are on the
roofs of the cars, approximately 1.5m above the ground. What is the
maximum communication distance between the dispatcher and a taxi?
a. 21 km
b. 30 km
c. 25 km
d. 33 km
211. The E layer of the ionosphere aid _________ propagation and reflects
_________ waves
a. MF, HF
b. HF, MF
c. LF, MF
d. MF, LF
212. When microwave signals follows the curvature of the earth, it is known
as
b. ducting
c. tropospheric scatter
d. ionospheric scatter
213. If the polarization vector rotates 360 degrees as the wave moves one
wavelength through space and field strength is equal at all angles of
polarization, the polarization is _________.
a. Vertically polarized
b. Horizontally polarized
c. Circularly polarized
d. Elliptically polarized
214. _________ travels essentially in a straight line between the transmit and
the receive antennas
a. Direct waves
b. Sky waves
c. Space waves
d. Surface waves
215. Variations brought about the revolution of the earth around the sun
a. weather variation
b. cyclical variation
c. diurnal variation
d. seasonal variation
216. The dielectric strength of air is about 3MV/m. Arching is likely to take
place at field strengths greater than that. What is the maximum power
density of an electromagnetic wave in air?
a. 40 GW/m^2
b. 15.5 GW/m^2
c. 23.9 GW/m^2
d. 18.9 GW/m^2
217. It is a single location from which rays propagate equally in all directions
a. point source
b. omnidirectional source
c. ideal polarization
d. isotropic polarized
219. The critical frequency at a particular time is 11.6MHz. What is the MUF
for a transmitting station if the required angle of incidence for propagation to
a desired destination is 70 degrees?
a. 34 MHz
b. 45 MHz
c. 40 MHz
d. 15.5 MHz
220. The rate at which energy passes through a given surface area in free
space is called _________.
a. capture power
b. capture area
d. power density
221. A radio wave moves from air (relative permittivity is 1) to glass (relative
permittivity is 7.8). Its angle of incidence is 30 degrees. What is the angle of
refraction?
a. 10.3 degrees
b. 11.2 degrees
c. 20.4 degrees
d. 0.179 degrees
222. It is the intensity of the electric and the magnetic fields of the
electromagnetic wave propagating in free space
a. field intensity
b. field density
c. power intensity
d. power intensity
a. Heinrich R. Hertz
b. Guglielmo Marconi
a. HF
b. VHF
c. UHF
d. VLF
225. A point source that radiates power at a constant rate uniformly in all
directions.
a. isotropic source
b. isotropic radiator
c. point source
d. any of these
226. The transmitting distance with direct waves is limited to short distances
and strictly a function of the _________ of the transmitting and receiving
antenna.
a. frequency
b. phase
c. power
d. height
a. 2.12
b. 1.15
c. 2.54
d. 1.90
a. reflection
b. diffraction
c. refraction
d. dispersion
a. absorption
b. attenuation
c. distance loss
d. power dissipation
230. The signal refracted back from the ionosphere strikes the earth and is
reflected back up to the ionosphere again to be bent and sent back to earth.
a. skip transmission
b. multi-hop transmission
c. multi transmission
d. hop transmission
a. absorption
b. attenuation
c. power dissipation
d. distance loss
233. _________ is the signal that is radiated by the antenna into the
atmosphere where it is bent or reflected back to earth.
a. Selective fading
b. Polarization fading
c. Interference fading
d. Absorption fading
a. refraction
b. scattering
c. reflection
d. diffraction
a. Frequency modulation
b. Amplitude modulation
c. Phase modulation
d. Pulse modulation
a. Hertzian principle
b. Maxwells principle
c. Huygens principle
d. Marconis principle
238. Calculate the electric field intensity, in volts per meter, 20 km from a 1kW source.
a. 3.44 mW/m
b. 7.65 mW/m
c. 8.66 mW/m
d. 1.45 mW/m
a. their frequency
240. Calculate the radio horizon for a 500-ft transmitting antenna and
receiving antenna of 20 ft.
a. 23.1 mi
b. 31.2 mi
c. 14.8 mi
d. 37.9 mi
241. Calculate the power received from a 20-W transmitter, 22,000 miles
from earth, if the receiving antenna has an effective area of 1600m^2
a. 4.06 x 10^-12 W
b. 2.03 x 10^-12 W
c. 1.02 x 10^-12 W
d. 0.91 x 10^-12 W
242. As electromagnetic waves travel in free space, only one of the following
can happen to them
a. absorption
b. attenuation
c. refraction
d. reflection
a. Space wave
b. Surface wave
c. Terrestrial wave
d. Sky-wave
244. Calculate the power density in watts per square meter (on earth) from a
10-W satellite source that is 22,000 miles from earth.
a. skipping
b. attenuation
c. absorption
d. fading
a. E-layer
b. S-layer
c. isothermal region
d. ionosthermal region
a. solar intensity
b. sunspot
c. solar flare
d. solar flux
a. is caused by reflection
a. Surface waves
b. Sky waves
c. Direct waves
d. Space waves
a. Ground waves
b. Sky waves
c. Surface waves
d. Space waves
51. The curvature of the Earth presents a horizon to space wave propagation
commonly called _________.
a. Optical horizon
b. Radio horizon
c. Horizontal horizon
d. Vertical horizon
252. Electromagnetic waves that are directed above the horizon level is
called _________.
a. direct waves
b. sky waves
c. space waves
d. surface waves
253. The refracting and reflecting action of the ionosphere and the ground is
called
a. sliding
b. skipping
c. hopping
d. boosting
a. Electrical signal
b. Electromagnetic waves
c. Magnetic waves
d. Electromagnetism
255. The layer of the ionosphere which farthest from the sun
a. D layer
b. E layer
c. F1 layer
d. F2 layer
a. running
b. fading
c. ghosting
d. snowing
a. LF and MF
b. MF and HF
c. HF and VHF
a. Kennely-Heavisides
b. Sporadic-E layer
c. E-densed layer
d. Kennely layer
a. critical angle
c. critical frequency
d. virtual height
a. numerical aperture
b. incident angle
c. critical angle
d. refracted angle
a. rays
b. electromagnetic wave
c. wavefront
d. isotropic source
262. It is the height above Earths surface from which a reflected wave
appears to have been reflected.
a. virtual height
b. maximum height
c. vertical height
d. horizontal height
263. It is the highest frequency that can be used for sky wave propagation
between two specific points on Earths surface
c. critical frequency
d. maximum frequency
a. E field
b. H field
c. propagation
c. critical frequency
d. maximum frequency
266. It is defined as the minimum distance from the transmit antenna that a
sky wave at a given frequency will be returned to earth.
a. skip distance
b. skip zone
267. At distance greater than the skip distance, two rays can take different
paths and still be returned to the same point on Earth. The two rays are
called lower rays and _________.
a. Pedersen ray
b. Light ray
c. Huygens ray
d. Millers ray
a. ESD
b. EMI
c. RFI
d. ESI
269. The area between where the surface waves are completely dissipated
and the point where the first sky wave returns to earth is called _________.
a. skip distance
c. optical horizon
d. quiet zone
270. The undesired radiated energy that may cause interference with other
electronic equipment in the vicinity.
a. ESD
b. EMI
c. RFI
d. ESI
c. path loss
d. any of these
273. For a carrier frequency of 6 GHz and a distance of 50 km, determine the
free-space path loss
a. 132 dB
b. 123 dB
c. 142 dB
d. 152 dB
a. 20 mi
b. 33.2 mi
c. 38.7 mi
d. 53.2 mi
a. SIDs
b. Fading
c. Atmospheric storms
d. Faradays rotation
a. VHF
b. UHF
c. HF
d. Microwave
277. VLF waves are used for some types of services because
a. direct wave
b. sky wave
c. surface wave
d. standing wave
279. Indicate which of the following frequencies cannot be used for reliable
beyond-the-horizon terrestrial communications without repeaters:
a. 20 kHz
b. 15 MHz
c. 900 MHz
d. 12 GHz
a. ground wave
b. direct wave
c. surface waves
d. sky wave
282. The ionosphere has its greatest effect on signals in what frequency
range?
b. 3 to 30 MHz
c. 30 to 300 MHz
283. Distances near the skip distance should be used for sky-wave
propagation
a. to avoid tilting
b. 3 to 30 MHz
c. 30 to 300 MHz
a. diffused
b. absorbed
c. refracted
d. reflected
286. Helical antenna are often used for satellite tracking at VHF because of
a. troposcatter
b. superrefraction
c. ionospheric refraction
b. a broadband antenna
c. frequency diversity
d. space diversity
288. It is defined as the ratio of the electric field intensity of the reflected
wave to that of the incident wave
a. refractive index
b. numerical aperture
c. reflection coefficient
d. absorption coefficient
289. It is the measure of energy received per unit time, per unit area, per
unit frequency interval.
a. solar intensity
b. sunspot
c. solar flare
d. solar flux
a. El Nio
b. La Nia
c. Maunder period
d. Sunspots
291. As a ground-wave signal moves away from the transmitter, the ground
wave eventually disappears due to the
a. absorption
b. tilting
c. refraction
d. diffraction
292. It is the lowest layer of the atmosphere where all weather disturbances
takes place
a. D layer
b. Stratosphere
c. Ionosphere
d. Troposphere
293. It is the lower limit of the range of frequencies that provide useful
communication between two given points by the way of the ionosphere.
a. MUF
b. LUF
c. OWF
d. MMF
294. It is the area that lies between the outer limit of the ground-wave range
and the inner edge of energy return from the ionosphere
a. skip distance
b. skip zone
c. virtual height
d. optical horizon
295. Variations brought about by the rotation of the earth around its axis.
a. cyclical rotation
b. seasonal variation
c. diurnal variation
d. weather variation
b. Dillenger fadeouts
c. Mogul-Delliger fadeouts
d. Any of these
a. interference fading
b. absorption fading
c. selective fading
d. polarization fading
a. one-third
b. four-third
c. two-third
d. twice
a. height inversion
b. depth inversion
c. temperature inversion
d. ionospheric inversion
a. duct
b. dielectric area
c. gateway
d. window
d. None of these
a. Mark-Space Layers
b. Davidson-Miller Layers
d. Maxwell Layer
a. Characteristics impedance
b. Load impedance
c. Intrinsic impedance
d. Wave impedance
304. The field strength of a radio signal varies according to the output or
transmitted power and the distance of the receiver from the transmitter. This
wave behavior is described by
b. Huygens Principle
c. Faradays Law
305. The antenna theory states that reception and transmission functions are
interchangeable is
a. Poynting Theorem
b. Snells Law
c. Huygens Principle
d. Law of Reciprocity
a. ELF
b. HF
c. VLF
a. Sky wave
b. Tropospheric wave
c. Transionospheric wave
d. Ground wave
a. Ground waves
b. surface waves
c. sky waves
d. space waves
309. the ground wave eventually disappear as it moves farther away from
the transmitter, because of
a. tilting
b. reflection
c. refraction
d. diffraction
310. as electromagnetic waves travel in free space, only one of the following
can happen
a. absorption
b. attenuation
c. refraction
d. reflection
312. If the direction of the electric field of a radio wave is horizontal. That
wave is known to be _____ polarized.
a. Negatively
b. Vertically
c. Positively
d. Horizontally
a. Miller effect
b. Permeability
c. Capacitance
d. Permitivity
a. Snells Law
b. Maxwells Law
c. Huygens Principle
d. Archimedes Principle
315. A number, which when multiplied by the speed of light in free space
gives the speed of light in the medium in question is
a. Fibonacci number
b. Fermats number
c. Velocity factor
d. K-factor
316. The ability of a radio wave to be bent slightly over the edge of a sharp
obstacle such as a steep hill or mountain top is
a. Diffraction
b. Reflection
c. Refraction
d. Attenuation
a. Sky wave
b. Radio wave
c. Surface wave
a. Constellation diagram
b. Argand diagram
c. Funicular diagram
d. Radiation pattern
a. Inductance
b. Permittivity
c. Permeability
d. Power density
a. Tilting
b. Ground absorption
c. Atmospheric absorption
321. The transmission of radio waves far beyond line of sight distances by
using high power and large transmitting antennas to beam the signal upward
into the atmosphere and a similar large receiving antenna to pick up a small
portion of the signal scattered by the atmosphere is called
c. Either a or b
a. Optimum height
b. Virtual height
c. Complex height
d. Critical height
323. The highest frequency whereby a wave will be returned back to earth by
an ionospheric layer having been beamed up at it and ranges from 5 to 12
MHz. For F2 layers. This frequency is directly proportional to the secant
function of the smallest angle, which allows reflection of sky waves.
a. Apex frequency
b. Critical frequency
c. Carrier frequency
d. Baseband frequency
324. The distant at which sky-wave signals are reflected back to earth
depend on
c. Both a and b
d. Both and b
326. The process by which a radio wave is bent and returned to earth from
one medium to another after striking them is
a. Reflection
b. Refraction
c. Diffraction
d. Absorption
a. Snells Law
b. Fishers Law
c. Hookes Law
d. Newtons Law
a. D layer
b. E layer
c. F layer
d. Vantress layer
329. This phenomenon occurs when the thicker air is on top instead of being
at the bottom when the temperature of water vapor gradient is lesser or
greater than the standard rate.
a. Thermal inversion
b. Horizontal ducting
c. Elevated ducting
d. Sporadic E
a. D-layer
b. E-layer
c. F layer
d. Vantress layer
a. Pressure
b. Temperature
c. Humidity
d. All of these
332. This ionospheric layer forms at night at about 300 km from the earths
surface and is responsible for long distance HF wave propagation due to
reflection and refraction. It splits during daytime due to the ionizing energy
from ultraviolet rays of the sun.
a. D layer
b. E layer
c. F layer
d. Vantress layer
333. When the transmitting and receiving antennas are line-of-sight of each
other, the mode of propagation is _____ wave.
a. Space or direct
b. Sky
c. surface
d. ground
a. Coulombs law
d. Lenzs Law
a. 6
b. 2
c. 8
d. 4
336. ________ is the extra ionization of the E-layer resulting to irregular and
intermittent reflection of frequencies of up to 80 MHz in temperate and lower
latitudes of frequencies of up to 80 MHz in temperate and lower latitudes. It
is variable in time of occurrence, height. Geographical distribution,
penetration frequency and ionization density.
a. Sporadic E
b. Dillinger Effect
c. Faraday rotation
d. Scintillations
a. Attenuation
b. Microbending
c. Dispersion
d. Multipath fading
a. Wave propagation
b. RF induction
d. Forward Scatter
339. The upper limit of frequencies that can be used at a specified time for
radio transmission between two points and involving propagation by
reflection from regular ionized layers of the ionosphere is
d. Carrier frequency
a. Huygens waves
b. Transverse waves
c. Longitudinal waves
d. Fraunhoffer waves
a. SIDs
b. Fading
c. Atmospheric storms
d. Faraday rotation
342. VLF waves are used for some types of services because
344. Distances near the skip distance should be used for sky-wave
propagation
a. To avoid tilting
345. The ground wave eventually disappears, as one moves away from the
transmitter, because of
d. Tilting
a. Is caused by reflection
b. Rayleigh Fading
c. Multi-path fading
d. None of these
a. Their frequency
a. RF propagation
b. Radio propagation
c. Wave propagation
d. All of these
c. Irregular oscillations
353. The region around an electrically charged body in which other charged
bodies are acted by an attracting or repelling force.
a. Electric field
b. Radiation field
c. Magnetic field
d. Electromagnetic field
355. Shows a surface of constant phase of a wave and is formed when points
of equal phase on rays propagated from the source are joined together.
a. Ray
b. Wavefront
c. Point source
d. Isotropic source
a. Ray
b. Wavefront
c. Point source
d. Isotropic source
357. Refers to the rate at which energy passes through a given surface area
in free space
a. Field intensity
b. Power density
c. Refractive index
d. Absorption coefficient
a. Field intensity
b. Power density
c. Refractive index
d. Absorption coefficient
a. Resistance
b. Field intensity
c. Characteristic impedance
d. A or C is correct
a. Inductance
b. Power density
361. A reduction in power density due to the inverse square law presumes
free-space propagation is called
a. Absorption
b. Wave attenuation
d. B or C is correct
d. A and B
d. A or C is right
b. The ratio of the light in free space towards the light in a given
medium
366. Why is it that rays traveling near the top of the medium travel faster
than those at the bottom?
c. The medium is less dense near the bottom and more dense at the
top
d. A and B
a. Rayleigh criterion
b. Huygens principle
c. Linear superposition
d. Reflection coefficient
370. Energy that has neither been radiated into space nor completely
transmitted
a. Modulated waves
b. Captured waves
c. Standing waves
d. Incident waves
371. What property of radio waves occurs whenever two or more waves
simultaneously occupy the same point in space?
a. Reflection
b. Refraction
c. Diffraction
d. Interference
a. Isobaric source
b. Isotropic source
c. Isentropic source
d. Isothermal source
a. 300,000 km/sec
b. 200 km/sec
c. 400,000 km/sec
d. 100,000 km/sec
a. Electric field
b. Radiation field
c. Magnetic field
d. Electromagnetic field
d. Is not possible
a. Ground-wave propagation
c. Sky-wave propagation
d. All of these
378. At frequencies below 1.5 MHz, what propagation provides the best
coverage?
a. Ground wave
b. Space wave
c. Sky wave
d. All of these
a. Gradient density
c. Absorption coefficient
a. Power
b. Terrain
c. Frequency
d. B and C
c. Radio navigation
d. All of these
a. Standard atmosphere
b. Optical horizon
c. Radio horizon
d. All of these
c. Relative conductivity
d. All of these
385. A special condition which occurs when the density of the lower
atmosphere is such that electromagnetic waves are trapped between it and
earths surface
a. Duct propagation
a. Increase
b. Decrease
c. Remain constant
d. Decrease by a factor of 2
a. Increasing refraction
b. Decreasing reflection
c. Increasing diffraction
d. Decreasing interference
a. D layer
b. E layer
c. Kennelly-Heaviside layer
d. B or C
389. The sporadic E layer is a thin layer with a very high ionization density. It
is considered separately from the other layers and when it appears, gives an
unexpected improvement in long distance radio transmissions. What
cause(s) its unpredictable appearance?
a. Sunspot activity
b. Sunspot cycle
c. Solar flares
d. A and C
390. The region in the ionosphere with a very high ionization density at
roughly 55 to 90 miles and is used for frequencies up to about 20 MHz. It is
gone completely at midnight.
a. D layer
b. E layer
c. F layer
d. G layer
391. A layer in the ionosphere which is the most important reflecting medium
fir HF radio waves. It has 2 sublayers, at 90 to 250 mi height
a. A layer
b. D layer
c. E layer
d. F layer
392. The apparent height of the ionized layer and is always greater than the
actual height
a. Critical height
b. Virtual height
c. Maximum height
d. Imaginary height
a. Hop
b. Skip distance
c. Actual distance
d. Critical distance
394. Concerns to the highest frequency that is able to return to earth when
beamed at a certain angle of incidence
a. Relative frequency
b. Optimum frequency
c. Resonant frequency
395. In ________, the distant of each succeeding hop from earth to ionosphere
and back is also the skip distance.
a. Hop transmission
b. Single transmission
c. Unihop transmission
d. Multihop transmission
396. Concerns to the single reflection of a radio wave form the ionosphere
back to earth.
a. Jog
b. Hop
c. Skip
d. Fading
397. The fluctuation of signal strength at the receiver that are caused by
changes in the transmission medium
a. Fading
b. Hopping
c. Skipping
d. Diversity
a. Fading techniques
b. Diversity techniques
c. Transverse techniques
d. Transmission techniques
a. Diversity
b. Space diversity
c. Frequency diversity
d. Polarization diversity
400. To increase the availability of the system, a method in which the output
of a transmitter is fed to two or more antennas that are physically separated
by an appreciable number of wavelengths.
a. Space diversity
b. Frequency diversity
c. Polarization diversity