mcq's radiowave propagation
TRANSCRIPT
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RADIOWAVE PROPAGATION
1. ________ is the amount of
voltage induced in wave by an
electromagnetic wave.
a. receive voltage
b. magnetic inductionc. field strength
d. power density
2. An electromagnetic wave
consists of ___________.
a. both electric and magneticfields.
b. an electric field only
c. a magnetic field only
d. non-magnetic field only
3. What is the lowest layer of
the ionosphere
a. !1
b. !2
c. "
d. #
$. Who propounded electro
magnetic radiation theory
a. %ir "dward Appletonb. &ames 'ler( )a*well
c. 'hristian +uygens
d. %ir ,saac ewton
. /he #0 " and ! layers are
(nown as ____________.
a. )ar( space ayersb. #avinson- )iller ayers
c. ennely +eaviside ayers
d. Appleton ayers
4. #ifferent grouping of the
electromagnetic spectrum.
a. band
b. bandwidth
c. channel
d. group
5. What is the relation in
degrees of the electric and
magnetic fields in anelectromagnetic wave
a. 167 degrees
b. 87 degrees
c. 257 degreesd. $ degrees
6. A changing electric field
gives rise to ________.
a. a magnetic field
b. sound field
c. electromagnetic waves
d. near and far fields
8. !re9uencies in the :+!
range propagate by means of
a. ground waves
b. s(y wavesc. surface waves
d. space waves
17. ,n electromagnetic waves0
polari;ation __________.
a. is caused by reflectionb. is due to the transverse
nature of the waves
c. results from the
longitudinal nature of thewaves
d. is always vertical in an
isotropic medium
11. "lectromagnetic Waves are
refracted when they
___________.
a. pass into a medium of
different dielectric constants
b. are polari;ed at right
angles to the direction ofpropagation
c. encounter a perfectly
conducting surfaced. pass through a small slot
in a conducting plane
12. What is the highest layerof the atmosphere
a. ionosphere
b. stratosphere
c. troposphere
d. o;one layer
13. What is the thic(est layer
of the ionosphere
a. !2
b. !1
c. #
d. "
1$. "ffective "arth radius totrue earth radius ratio.
a. inde* of refraction
b. factor
c. !resnel ;oned. path profile
1. !ading due to interference
between direct and reflected
rays.
a. atmospheric-multipath
b. !resnel ;one
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c. reflection-multipath
d.
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d. hori;ontal wave
37. ight goes from medium A
to medium at angle of
incidence of $7 degrees. /he
angle of refraction is 37degrees. /he speed of light in
a. is the same as that in A
b. is greater than that in A
c. maybe any of these0
depending on the specificmedium
d. is less than that in A
31. ,n a vacuum0 the speed ofan electromagnetic wave
a. depends on its constant
b. depends on its wavelength
c. depends on its electric
and magnetic fields
d. is a universal constant
32. /he depth of an obBect
submerged in a transparent
li9uid
a. always seems more that itsactual depth
b may seem less or more than
its actual depth0 depending onthe obBect
c. always seems less than its
actual depth
d. may seem less or more thanits actual depth0 depending on
the transparent li9uid
33. What is a wave front
a. a voltage pulse in a
conductor
b. a current in a conductor
c. a fi*ed point in an
electromagnetic wave
d. a voltage pulse across a
resistor
3$. =+! ship station
transmitters must have thecapability of reducing carrier
power to
a. 1 W
b. 17 Wc. 2 W
d. 7 W
3. )ost of the effects an
electro magnetic wave produces
when it interacts with matter
are due to its
a. magnetic field
b. speed
c. fre9uency
d. electric field
34. A mobile receivere*periences CdeadD areas of
reception as a result of
a. atmospheric absorption
b. tropospheric scatter
c. sporadic "
d. shading of the
35. When the electric field is
perpendicular in the surfaceof the earth0 what is the
polari;ation of the /") wave
a. elliptical
b. vertical
c. hori;ontal
d. circular
36. When the magnetic field is
perpendicular to the surface
of the earth0 what is the
polari;ation of the /") wavea. circular
b. hori;ontal
c. verticald. elliptical
38. When the magnetic field is
parallel to the surface of theearth0 what is the
polari;ation of the /") wave
a. elliptical
b. hori;ontal
c. vertical
d. circular
$7. What are the two
interrelated fields considered
to ma(e up an electromagnetic
wave
a. an electric field and a
current field
b. an electric field andvoltage field
c. an electric field and a
magnetic field
d. a voltage and currentfields
$1. +ow does the bandwidth of
the transmitted signal affect
selective fading
a. it is more pronounced at
narrow bandwidths
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b. it is e9ually pronounced
at both narrow and wide
bandwidths
c. it is more pronounced at
wide bandwidths
d. the receiver bandwidthdetermines the selective
fading
$2. A wide-bandwidth
communications systems in
which the
predetermined se9uence.
a. amplitude compandored
single sidebandb. %,/Earallel to the magnetic
field and perpendicular to the
wave direction
d. >erpendicular to the
magnetic field and parallel to
the wave direction
44. /he highest fre9uencies
are found in
a. I-rays
b.
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56. /otal internal reflection
can occur when light passes
from one medium to another
a. /hat has a lower inde* of
refractionb. /hat has a larger inde* of
refraction
c. /hat has the same inde* of
refraction
d. At less than the critical
angle
58. When the light ray
approaches a glass-air
interface from the glass sideat the critical angle0 the
angle of refraction is
a. 7
b. 87 degrees
c. $ degrees
d. "9ual to the angle of
incidence
67. /he brightness of light
source is called its luminous
intensity 0 whose unit isa. 'andela
b. u*
c. umend. !ootcandle
61. uminous efficiency is
least for aa. ow-wattage light bulb
b. )ercury vapor lamp
c. +igh-wattage light bulb
d. !luorescent tube
62. /he minimum illumination
recommended for reading is
a. 6777 cd
b. 6777 l*
c. 6777 lm
d. 677 W
63. ight enters a glass plate
whose inde* of refraction is1.4 at an angle of incidence
of 37 degrees . the angle of
refraction is
a. 16 degreesb. $6 degrees
c. 18 degrees
d. 3 degrees
6$. ight leaves a slab of
transparent material whose
inde* of refraction is 2 at an
angle of refraction of 7
degrees. /he angle of
incidence is
a. 7 degrees
b. $ degrees
c. 37 degreesd. 87 degrees
6. ight enters a glass plate
at an angle of incidence of $7
degrees and is refracted at an
angle refraction of 2degrees. /he inde* refraction
of the glass is
a. 7.42
b. 1.2c. 7.44
d. 1.4
64. An underwater swimmer
shines a flash light beam
upward at an angle of
incidence of $7 degrees. /he
angle of refraction is 47
degrees. /he inde* of
refraction of water is
a. 7.45b. 1.3
c. 7.5$
d. 1.
65. /he critical angle of
incidence for light going from
crown glass KnF1.L to iceKnF1.3L is
a. 12 degrees
b. 7 degrees
c. $2 degrees
d. 47 degrees
66. /he solid angle subtended
by a hemisphere about its
center is
a. M@2 sr
b. 2 M sr
c. M sr
d. depends on the radius of
the hemisphere
68. the luminous flu* emitted
by a 47-cd isotropic light
source is concentrated on anarea of 7.m2. the
illumination of the area is
a. 8.4 l*
b. 355 l*
c. 127 l*
d. 176 l*
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87. )icrowave signals
propagate by way of the
a. #irect wave
b. %(y wave
c. %urface wave
d. %tanding wave
81. /he ionosphere causes
radio signals to be
a. #iffused
b. Absorbed
c. rincple
d. !aradayGs law
88. gets in contact with the
ionosphere and reflected by
it.
a. %pace wave
b. %(y wave
c. %urface wave
d. %atellite wave
177. +ighest layer in the
ionosphere
a. !1b. #
c. !2
d. "171. e*t lowest layer in the
ionosphere.
a. #
b. "c. !1
d. !2
172. What is the primary cause
of ioni;ation in the
atmosphere
a. %un spot
b. 'osmic rays
c. Halactic disturbance
d. :ltraviolet radiation
173. Which layer does not
disappear at night
a. #b. "
c. !1
d. !2
17$. Which of the following
uses surface wave propagation
a. "!
b. =!
c. )!
d. All of these
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17. /he ability of the
ionosphere to reflect a radio
wave bac( to the earth is
determined by
a. Eperating fre9uency
b. ,on densityc. Angle of incidence
d. All of these
174. +ighest fre9uency that
can be used for s(y wave
propagation between two givenpoints on earth.
a. 'ritical fre9uency
b. ):!
c. 'ut off fre9uencyd. :+!
175. /he shortest distance
measured along the earthGs
surface that a s(y wave is
returned to earth.
a. ):!
b. Nuarter-wavelength
c. %(ip distance
d. %(ip ;one
176. !luctuation in the signal
strength at the receiver.
a. ,nterferenceb. !ading
c. /rac(ing
d. =ariable fre9uency
178. /wo or more antennas are
used separated by several
wavelengths
a. %pace diversity
b. !re9uency diversity
c. +ybrid diversity
d. >olari;ation diversity
117. /wo or more receivers are
used using a single antenna.
a. %pace diversity
b. !re9uency diversity
c. +ybrid diversity
d. >olari;ation diversity
111. Ene of the following is
not a cause of fading.
a. ,nterference between upperand lower rays of a s(y wave.
b. %(y waves arriving at
different number of hops
c. ,nterference due to ground
reflected wave and s(y wave
d. #iversity
112. What do you call the
gigantic emissions of hydrogen
from the sun
a. %olar flares
b. %,#s
c. ennely-+eavisided. %un spots
113. %udden ionospheric
disturbance
a. %olar flares
b. %,#sc. %un spots
d. ,ntertropical convergence
11$. A means beyond the lineof sight propagation of :+!
signals.
a. )icrowave propagation
b. %pace wave propagation
c. /roposcatter propagation
d. %urface wave propagation
11. /wo directional antennas
are pointed so that their
beams intersect in the
troposphere.a. %(ywave
b. %urface wave
c. )icrowaved. /roposcatter
114. %uper refraction.
a. #uctingb. /rposcatter
c. %(ywave
d. %pace wave
115. A layer of warm air
trapped above cooler air
a. /roposphere
b. %,#
c. #uct
d. +uygenGs principle
116. 'orresponds to voltage
a. "lectric field
b. )agnetic fieldc. Hyro
d. #irection of propagation
118. Absence of receptiona. %(ip distance
b. )a*imum usable
c. %hadow ;one
d. /wilight ;one
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127. "ach point in a spherical
waveform maybe a source of a
secondary spherical wavefront.
a. %enllGs law
b. +uygenGs principle
c.
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c. =!
d. =+
13$. /he range of fre9uency
band termed as super high
fre9uency K%+!L is within_________.
a. 37 377 H+;
b. 37 377 )+;
c. 3 37 H+;
d. 377 3777 )+;
13. "lectric field that lies
in a plane perpendicular to
the earthGs surface.
a. circular polari;ationb. vertical polari;ation
c. hori;ontal polari;ation
d. elliptical polari;ation
134. /he magnetic field of an
antenna is perpendicular to
the earth. /he antennaGs
polari;ation
a. is vertical
b. is hori;ontal
c. is circulard. cannot be determined from
the information given
135. /he surface wave is
effective only at fre9uencies
below about _________ )+;.
a. 37b. 3
c. 377
d. 7.3
136. What wave propagation are
attenuated within a few miles
a. space
b. s(y
c. ground
d. direct
138. What happens to wave
velocity as it passes from air
to ionospherea. increases
b. decreases
c. remain the same
d. not a factor
1$7. What wavelength
radiations tend to be
transmitted entirely between
ionosphere and earth
a. long
b. short
c. medium
d. millimeter
1$1. What effect do sunspots
have on the ionosphere
a. ma(es more rare andregular
b. ma(es more dense and
irregular
c. ma(es less dense and
regular
d. ma(es less dense andirregular
1$2. What is a double-hop
signala. ground0 ionosphere0 ground
and bac( to ionosphere
b. ground0 ground0
ionosphere0 and ionosphere
c. ionosphere0 ionosphere0
ground and ground
d. ionosphere0 ground0
ionosphere and bac( to ground
1$3. What is the maBor cause
of fadinga. phase difference
b. topographic variation
c. climated. ionosphere variation
1$$. Where is the s(ip ;one
a. between the s(y and thefirst reflected wave
b. between end of ground and
first reflected wave
c. between end of ground and
farthest reflected wave
d. between the end of s(y to
the farthest reflected wave
1$. What wave is the same day
or night
a. s(y
b. space
c. direct
d. ground
1$4. Why do +! communications
system shift fre9uencies at
different times of daya. to ta(e advantage of best
reflected signals
b. to conserve the energy
used
c. to create diversity
d. to improve noise
performance
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1$5. %catter transmission is
used at what fre9uencies
a. "+! and =!
b. +! and =+!
c. =+! and :+!d. "! and =!
1$6. Ever what areas ducts
often form
a. desert
b. waterc. forest
d. mountain
1$8. >olari;ation named for_________ component of the
wave
a. static
b. magnetic
c. direction
d. propagation
17. What polari;ation is
employed in an A)
broadcasting
a. hori;ontalb. parallel
c. transverse
d. vertical11. What propagation
condition is usually indicated
when a =+! signal is received
from a station 77 miles awaya. #-layer absorption
b. !araday rotation
c. /ropospheric ducting
d. )oonbounce
12. +ow does the bandwidth of
the transmitted signal affect
selective fading
a. ,t is more pronounced at
wide bandwidths
b. ,t is more pronounced at
narrow bandwidths
c. ,t is e9ually pronounced
in both narrow and widebandwidth
d. /he receiver bandwidth
determines the selective
fading effect
13. +ow much farther does the
radio-path hori;on distance
e*ceed the geometric hori;on
a. y appro*imately 1O of
the distance
b. y appro*imately twice the
distance
c. y appro*imately one-half
the distance
d. y appro*imately four
times the distance
1$. #etermine the d gain of
a receiving antenna which
delivers a microvolt signal to
a transmission line over that
of an antenna that delivers a2 microvolt signal under
identical circumstances.
a. -4
b. -3c. 4
d. 3
1. What is transe9uatorial
propagation
a. >ropagation between two
points at appro*imately the
same distance north and south
of the magnetic e9uator
b. >ropagation between two
points on the magnetic e9uatorc. >ropagation between two
continent by way of ducts
along the magnetic e9uatord. >ropagation between any
two station at the same
latitude
14. nife edge diffractionP
a. ,s the bending of :+!
fre9uency radio waves around a
building0 mountain or
obstruction
b. 'auses the velocity of
wave propagation to be
different than the original
wave
c. oth a and b above
d. Attenuate :+! signal
15. /he average range for =+!
communications isa. miles
b. 1 miles
c. 37 miles
d. 177 miles
16. A 77 (+; radiates 77 W
of power. /he same antenna
produces a field strength
e9ual 17 1. m=@0 ,f the power
delivered by the antenna is
increased to 1 (W0 what would
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be the e*pected field
intensity
a. 3 m=@m
b. 1.532 m=@m
c. 2.12 m=@m
d. 1.$4 m=@m
18. /he earthGs layer is
struc( by a meteorQ a
cylindrical region of free
electron is formed at what
layer of the ionospherea. !1 layer
b. " layer
c. !2 layer
d. # layer
147. What happens to a radio
wave as it travels in space
and collides with other
particles
a. inetic energy is given up
by the radio wave
b. inetic energy is gained
by the radio wave
c. Aurora is created
d. othing happens sinceradio waves have no physical
substance
141. !ind the characteristic
impedance of polyethylene0
which has a dielectric
constant of 2.$.a. 143.8 ohms
b. 355 ohms
c. 2$3 ohms
d. 27 ohms
142. What is the ma*imum range
for signals using
transe9uatorial propagation
a. About 1777 miles
b. About 277 miles
c. About 777 miles
d. About 577 miles
143. 'alculate the electricfield intensity in millivolts
per meter at 37 (W from a (m
source.
a. 187 m=@mb. 8.$8 u=@m
c. 7.168 W@m
d. 13.$14 =@m
14$. What is the inde* of
refraction of a certain
substance if light travels
through the substance at 177
meters at a time it is 1$7
meter to air
a. 1.163
b. 1.$
c. 7.51$d. 7.6$
14. What s selective fading
a. A fading effect caused by
small changes in beam heading
at the receiving stationb. A fading caused by phase
difference between radio wave
components of the same
transmission as e*perienced atthe receiving station
c. A fading caused by large
changes in the height of the
ionosphere as e*perienced at
the receiving station
d. A fading effect caused by
the time difference between
the receiving and transmitting
stations
144. /o what distance is =+!propagation ordinarily
limited
a. Appro*imately 177 milesb. Appro*imately 77 miles
c. Appro*imately 177 miles
d. Appro*imately 2777 miles
145. Why does the radio path
hori;on distance e*ceed the
geometric hori;on
a. "-layer s(ip
b. #-layer s(ip
c. Auroral s(ip
d.
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e*perienced in the receiving
station
c. /ime difference between
the receiving and transmitting
station
d. >hase differences betweenthe radio waves components of
the same transmission as
e*perienced in the receiving
station
157. #etermine the criticalfre9uency value of an +!
signal if its ma*imum usable
fre9uency is 577.7 (+; at 3
degrees incidence.a. $834.6 (+;
b. 55 (+;
c. $7$$ (+;
d. $876.5 (+;
151. What is the propagation
effect called when phase
difference between radio wave
components of the same
transmission are e*periences
at the recovery stationa. !aradayGs rotation
b. #iversity reception
c. %elective fadingd. >hase shift
152. What is the best time for
transe9uatorial propagationa. )orning
b. oon
c. Afternoon or early evening
d. /ranse9uatorial
propagation only wor(s at
night
153. /he dielectric strength
of a certain medium is about
2.6 )=@m. what is the ma*imum
power density of an
electromagnetic wave in this
medium
a. 23.8 HW@ s9. mb. 45.5 HW@ s9. m
c. 21. HW@ s9. m
d. 4.64 HW@ s9. m
15$. What is the (nife edge
diffraction
a. Allows normally line-of-
sight signals to bend around
sharp edges0 mountain ridges0
building and other obstruction
b. Arching in sharp bends of
conductors
c. >hase angle image
reBection
d. ine-of-sight causing
distortion to other signals
15. /he total power delivered
to the radiator of an
isotropic antenna is 2770 777
W. determine the power density
at a distance of 177 metersa. 1.8 W@s9 m
b. 2$.$8 W@s9 m
c. 3.16 W@s9 m
d. 2$$.8 W@s9 m
154. /he bending of radio
waves passing over the top of
a mountain range disperse a
wea( portion of the signal
behind the mountain is
a. "ddy-current phase effect
b. nife-edge diffraction
c. %hadowing
d. )irror refraction effect
155. A radio wave moves from
air KerF1L to glass KerF5.6L.
,ts angle of incidence is 27degrees. What is the angle of
refraction
a. 5 degrees
b. 28 degreesc. 17.3 degrees
d. 52.58 degrees
156. A dipole antenna re9uires
to be feed with 27 (W of power
to produce a given signal
strength available with an
input power of 11 (W. What is
the d gain obtained by the
use of the reflector Kgain
referred to this particular
dipoleL
a. -2.4 d
b. 2.4 dc. .18 d
d. -.18 d
158. What is a wavefronta. A voltage pulse in a
conductor
b. A current pulse in a
conductor
c. A voltage pulse across a
resistor
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d. A fi*ed point in an
electromagnetic wave
167. What is meant by
referring to electromagnetic
waves as having circularpolari;ation
a. /he electric field is bent
into a circular shape
b. /he electric field rotates
c. /he electromagnetic wave
continues to circle the earthd. /he electromagnetic wave
has been generated by a 9uad
antenna
161. An automobile travels at
87 (m@h0 find the time between
fades if the car uses a
cellphone at 677 )+;
a. 11.2 ms
b. 1 ms
c. 5. ms
d. $.5 ms
162. When the electric field
is parallel to the surface ofthe earth0 what is the
polari;ation of the
electromagnetic wavea. =ertical
b. +ori;ontal
c. 'ircular
d. "lliptical
163. At what speed do
electromagnetic waves travel
in space
a. Appro*imately 377 million
meters per second
b. Appro*imately $46 million
meters per second
c. Appro*imately 1640 377
feet per second
d. Appro*imately 377 million
miles per second
16$. /he ma*imum number offree electrons in a certain
ionospheric layer is 3.24* 17
? 13 per cu m. the critical
fre9uency isa. 1.3 )+;
b. 15.116 )+;
c. 3$.235 )+;
d. .574 )+;
16. What are electromagnetic
waves
a. Alternating currents in
the core of an electromagnet
b. A wave consisting of two
electric fields at right
angles to each other
c. A wave consisting of anelectric field and a magnetic
field at right angles to each
other
d. A wave consisting of two
magnetic fields at right
angles to each other
164. When the electric field
is perpendicular to the
surface of the earth0 what isthe polari;ation of the
electromagnetic wave
a. 'ircular
b. =ertical
c. +ori;ontal
d. "lliptical
165. #etermine the refractive
inde* of an ionospheric layer
with 1.45*17?4 free electrons
per cu m. /he fre9uency of theradio wave is 32 (+;.
a. 7.888
b. 7.834c. 7.84
d. 7.865
166. What is meant byelectromagnetic waves as
hori;ontally polari;ed
a. /he electric field is
parallel to the earth
b. /he magnetic field is
parallel to the earth
c. oth the electric and
magnetic field are hori;ontal
d. oth the electric and
magnetic field are vertical
168. Why do electromagnetic
waves not penetrate a good
conductor to any great e*tenta. /he electromagnetic field
induces currents in the
insulator
b. /he o*ide on the conductorsurface acts as a shield
c. ecause of eddy currents
d. /he resistivity of the
conductor dissipates the field
187. A transmitter has a power
output of 27 W at a carrier
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fre9uency of 32 )+;. it is
connected to an antenna with a
gain of 12 di. /he receiving
antenna is 17 (m away and has
a gain of di. 'alculate the
power delivered to thereceiver0 assuming free-space
propagation. Assume that there
are no losses or mismatches in
the system.
a. $7$ nW
b. 2.7$ nWc. 847 nW
d. 467 nW
181. What is the fre9uency touse for s(ywave propagation if
the critical fre9uency is 1
)+R and the angle of radiation
is 47 degrees
a. 15.32 )+;
b. 37 )+;
c. 2. )+;
d. 1$.522 )+;
182. When the magnetic field
is parallel tot eh surface ofthe earth0 what is the
polari;ation of the
electromagnetic fielda. 'ircular
b. +ori;ontal
c. "lliptical
d. =ertical
183. What is the inde* of
refraction of a certain medium
if the velocity of propagation
of a radio wave in this medium
is 1.25*17?6 m@s
a. 7.78
b. 7.431
c. 7.513
d. 1.84
18$. When the magnetic field
is perpendicular to the
surface of the earth0 what isthe polari;ation of the
electromagnetic field
a. 'ircular
b. +ori;ontalc. "lliptical
d. =ertical
18. !re9uencies most affected
by (nife-edge refraction are
a. ow and medium fre9uencies
b. +igh fre9uencies
c. =ery high and ultra high
fre9uencies
d. 177 (+; to 3 )+;
184. /he ionosphere causes
radio signals to bea. #iffused
b. Absorbed
c.
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d. #irect waves272. /he # layer of theionosphere reflects _________waves.
a. )! and +!
b. =! and )! c. )! and =+!
d. =! and !273. A diversity schemewherein the same radio signalis repeated or transmittedmore than once.
a. polari;ation diversity
b. field componentdiversity
c. time diversity d. fre9uency diversity
27$. /he disadvantage ofground wave propagation is
a. Hround waves re9uire arelativelyhigh transmission power
b. Hround waves arelimited to very low0 lowand medium fre9uenciesre9uiring large antennas
c. Hround losses veryconsiderably with surfacematerial
d. Any of these27. A range of microwavefre9uencies more easily passedby the atmosphere than theothers is called a
a. window
b. critical fre9uency
c. gyro fre9uency range
d. resonance in theatmosphere
274. ,t is simply theorientation of the electricfield vector in respect to thesurface of the "arth
a. >olari;ation
b. Wavefront
c. ower density
275. !or an isotropic antennaradiating 177W of power0 whatis power density 1777m fromthe source
a. 1.88 SW@m?2
b. 5.84 SW@m?2
c. 3.22 SW@m?2
d. 8.15 SW@m?2276. /he ground waveeventually disappears0 asmoves away from thetransmitter0 because of
a. interference from thes(y wave
b. loss of line-of-sightconditions
c. ma*imum single hop
distance limitations d. tilting
278. ,f the electric field ispropagating parallel to thesurface of the "arth0 thepolari;ation is _________.
a. 'ircular
b. =ertical
c. +ori;ontal
d. "lliptical
217. A ta*i company uses acentral dispatcher0 with anantenna at the top of a 1mtower0 to communicate withta*i cabs. /he ta*i antennasare on the roofs of the cars0appro*imately 1.m above theground. What is the ma*imumcommunication distance betweenthe dispatcher and a ta*i
a. 21 (m
b. 37 (m c. 2 (m
d. 33 (m211. /he " layer of theionosphere aid _________propagation and reflects_________ waves
a. )!0 +!
b. +!0 )!
c. !0 )!
d. )!0 !212. Whenmicrowave signals follows thecurvature of the earth0 it is(nown as
a. the !araday effect
b. ducting
c. tropospheric scatter
d. ionospheric scatter213. ,f the polari;ationvector rotates 347 degrees as
the wave moves one wavelengththrough space and fieldstrength is e9ual atall angles of polari;ation0the polari;ation is _________.
a. =ertically polari;ed
b. +ori;ontally polari;ed
c. 'ircularly polari;ed
d. "lliptically polari;ed21$. _________ travelsessentially in a straight line
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between the transmit and thereceive antennas
a. #irect waves
b. %(y waves
c. %pace waves
d. %urface waves21. =ariations brought aboutthe revolution of the eartharound the sun
a. weather variation
b. cyclical variation
c. diurnal variation
d. seasonal variation214. /he dielectric strengthof air is about 3)=@m. Arching
is li(ely to ta(e place atfield strengths greater thanthat. What is the ma*imumpower density of anelectromagnetic wave in air
a. $7 HW@m?2
b. 1. HW@m?2
c. 23.8 HW@m?2
d. 16.8 HW@m?2215. ,t is a single locationfrom which rays propagate
e9ually in all directions a. point source
b. omnidirectional source
c. ideal polari;ation
d. isotropic polari;ed216. #iffraction ofelectromagnetic waves
a. is caused byreflections from theground
b. arises only withspherical waveforms
c. will occur when thewaves pass through alarge slot
d. may occur around theedge of a sharp obstacle
218. /he critical fre9uency ata particular time is 11.4)+;.What is the ):! for atransmitting station if the
re9uired angle of incidencefor propagation to a desireddestination is 57 degrees
a. 3$ )+;
b. $ )+;
c. $7 )+;
d. 1. )+;227. /he rate at whichenergy passes through a givensurface area in free space iscalled _________.
a. capture power
b. capture area
c. captured power density
d. power density221. A radio wave moves fromair Krelative permittivity is
1L to glass Krelativepermittivity is 5.6L. ,tsangle of incidence is 37degrees. What is the angle ofrefraction
a. 17.3 degrees
b. 11.2 degrees
c. 27.$ degrees
d. 7.158 degrees222. ,t is the intensity ofthe electric and the magneticfields of the electromagneticwave propagating in free space
a. field intensity
b. field density
c. power intensity
d. power intensity223.
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c. 2.$
d. 1.87226. ,t is the deflection orbending of electromagneticwaves such as radio waves0
light or even sound when thewaves cross the boundary linebetween two mediums withdifferent characteristics.
a. reflection
b. diffraction
c. refraction
d. dispersion228. /he reduction of powerdensity with distance ise9uivalent to a power loss.
a. absorption
b. attenuation
c. distance loss
d. power dissipation237. /he signal refracted bac(from the ionosphere stri(esthe earth and is reflectedbac( up to the ionosphereagain to be bent and sent bac(to earth.
a. s(ip transmission
b. multi-hop transmission
c. multi transmission
d. hop transmission231. "lectromagnetic waves arerefracted when they
a. pass into a medium ofdifferent dielectricconstant
b. are polari;ed atright angles to thedirection of propagation
c. encounter a perfectlyconducting surface
d. pass through a smallslot in a conductingplane
232. /he reduction in powerdensity due to non free-spacepropagation
a. absorption
b. attenuation c. power dissipation
d. distance loss233. _________ is the signalthat is radiated by theantenna into the atmospherewhere it is bent or reflectedbac( to earth.
a. ground wave signal
b. s(y wave signal
c. space wave signal
d. direct waves signal
23$. ,t is a type of fadinghaving different effectdifferent fre9uencies
a. %elective fading
b. >olari;ation fading
c. ,nterference fading d. Absorption fading
23. ,t is defined as themodulation or redistributionof energy within a wave frontas it passes near the edge ofan opa9ue obBect.
a. refraction
b. scattering
c. reflection
d. diffraction234. What type of modulationis primarily used in groundwave propagation
a. !re9uency modulation
b. Amplitude modulation
c. >hase modulation
d. >ulse modulation235. ,t states that everypoint on a given sphericalwavefront can be considered as
a secondary point source ofelectromagnetic waves fromwhich other secondary waves orwavelets are radiated outward.
a. +ert;ian principle
b. )a*wellGs principle
c. +uygenGs principle
d. )arconiGs principle236. 'alculate the electricfield intensity0 in volts permeter0 27 (m from a 1-(Wsource.
a. 3.$$ mW@m
b. 5.4 mW@m
c. 6.44 mW@m
d. 1.$ mW@m238. /he absorption of radiowaves by the atmospheredepends on
a. their fre9uency
b. their distance from
the transmitter c. the polari;ation of
waves
d. is always vertical inan isotropic medium
2$7. 'alculate the radiohori;on for a 77-fttransmitting antenna andreceiving antenna of 27 ft.
a. 23.1 mi
b. 31.2 mi
c. 1$.6 mi
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d. 35.8 mi2$1. 'alculate the powerreceived from a 27-Wtransmitter0 220777 miles fromearth0 if the receiving
antenna has an effective areaof 1477m?2
a. $.74 * 17?-12 W
b. 2.73 * 17?-12 W
c. 1.72 * 17?-12 W
d. 7.81 * 17?-12 W2$2. As electromagnetic wavestravel in free space0 only oneof the following can happen tothem
a. absorption
b. attenuation
c. refraction
d. reflection2$3. "lectromagnetic wavestravelling within "arthGsatmosphere is called
a. %pace wave
b. %urface wave
c. /errestrial wave
d. %(y-wave
2$$. 'alculate the powerdensity in watts per s9uaremeter Kon earthL from a 17-Wsatellite source that is220777 miles from earth.
a. 3.15 * 17? -14 W@m?2
b. 4.3 * 17? -14 W@m?2
c. 2.31 * 17? -14 W@m?2
d. 1.21 * 17? -14 W@m?22$. ,t is termed used to
describe variations in signalstrength that occur at thereceiver during this time asignal is being received.
a. s(ipping
b. attenuation
c. absorption
d. fading2$4. /he constant temperaturestratosphere is called_________.
a. "-layer b. %-layer
c. isothermal region
d. ionosthermal region2$5. ,t is the tendency of thesun to have grayish-blac(blemishes0 seemingly at randomtimes and at random place0 onits fiery surface.
a. solar intensity
b. sunspot c. solar flare
d. solar flu*2$6. ,n electromagnetic waves0polari;ation
a. is caused byreflection
b. is due to thetransverse nature of thewaves
c. results from thelongitudinal nature ofwaves
d. is always vertical inan isotropic medium
2$8. ,t is an earth-guidedelectromagnetic wave thattravels over the surface of
the "arth a. %urface waves
b. %(y waves
c. #irect waves
d. %pace waves27. !re9uencies in the :+!range normally propagate bymeans of
a. Hround waves
b. %(y waves
c. %urface waves d. %pace waves
21. /he curvature of the"arth presents a hori;on tospace wave propagationcommonly called _________.
a. Eptical hori;on
b.
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2. /he layer of theionosphere which farthest fromthe sun
a. # layer
b. " layer
c. !1 layer d. !2 layer
24. A condition whichmanifest itself in the form ofdouble-image distortion
a. running
b. fading
c. ghosting
d. snowing25. /he # layer of the
ionosphere absorbs _________waves.
a. ! and )!
b. )! and +!
c. +! and =+!
d. =+! and :+!26. /he " layer of theionosphere is sometimes called_________
a. ennely-+eavisides
b. %poradic-" layer
c. "-densed layer
d. ennely layer28. ,t is defined as thehigher fre9uency that can bepropagated directly upward andstill be returned to earth bythe ionosphere
a. critical angle
b. ma*imum usablefre9uency
c. critical fre9uency
d. virtual height247. /he ma*imum verticalangle at which electromagneticwaves can be propagated andstill be reflected bac( by theionosphere
a. numerical aperture
b. incident angle
c. critical angle
d. refracted angle241. ,t is defined as theplane Boining all points ofe9ual phase
a. rays
b. electromagnetic wave
c. wavefront
d. isotropic source242. ,t is the height above"arthGs surface from which areflected wave appears to have
been reflected.
a. virtual height
b. ma*imum height
c. vertical height
d. hori;ontal height243. ,t is the highest
fre9uency that can be used fors(y wave propagation betweentwo specific points on "arthGssurface
a. optimum wor(ingfre9uency
b. ma*imum usablefre9uency
c. critical fre9uency
d. ma*imum fre9uency
24$. /he polari;ation ofelectromagnetic waves can bedetermined by the direction ofthe
a. " field
b. + field
c. propagation
d. both " and + field24. 6 percent of the ma*imumusable fre9uency K):!L iscalled _________.
a. ma*imum usablefre9uency
b. optimum wor(ingfre9uency
c. critical fre9uency
d. ma*imum fre9uency244. ,t is defined as theminimum distance from thetransmit antenna that a s(ywave at a given fre9uency willbe returned to earth.
a. s(ip distance
b. s(ip ;one
c. s(ip fre9uencydistance
d. s(ip ;one fre9uency245. At distance greater thanthe s(ip distance0 two rayscan ta(e different paths andstill be returned to the samepoint on "arth. /he two rays
are called lower rays and_________.
a. >edersen ray
b. ight ray
c. +uygenGs ray
d. )illerGs ray246. :ndesired radiated energyfrom a radio transmitter or inanother source.
a. "%#
b. "),
c.
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d. "%,248. /he area between wherethe surface waves arecompletely dissipated and thepoint where the first s(y wave
returns to earth is called_________.
a. s(ip distance
b. s(ip distance ;one
c. optical hori;on
d. 9uiet ;one257. /he undesired radiatedenergy that may causeinterference withother electronic e9uipment inthe vicinity.
a. "%#
b. "),
c.
d. "%,251. ,t is defined as the lossincurred by an electromagneticwave as it propagates in astraight line through a vacuumwith no absorption orreflection of energy fromnearby obBects.
a. free-space path loss
b. free space loss
c. path loss
d. any of these252. /o increasethe transmission distance of a:+! signal0 which of thefollowing should be done
a. increase the antennagain
b. increase antennaheight
c. increase transmitterpower
d. increase receiversensitivity
253. !or a carrier fre9uencyof 4 H+; and a distance of 7(m0 determine the free-spacepath loss
a. 132 d
b. 123 d
c. 1$2 d
d. 12 d25$. A microwave-transmittingantenna is 7 ft. high. /hereceiving antenna is 277 ft.high. /hema*imum transmission distanceis
a. 27 mi
b. 33.2 mi
c. 36.5 mi
d. 3.2 mi25. ,ndicate which one of thefollowing term applies totroposcatter propagation
a. %,#s b. !ading
c. Atmospheric storms
d. !aradayGs rotation254. ine-of-sightcommunications is not a factorin which fre9uency range
a. =+!
b. :+!
c. +!
d. )icrowave255. =! waves are used forsome types of services because
a. of the low powersre9uired
b. the transmittingantenna are of convenientsi;e
c. they are very reliable
d. affected by the solarcycle
256.)icrowave signals propagate byway of the
a. direct wave
b. s(y wave
c. surface wave
d. standing wave258. ,ndicate which of thefollowing fre9uencies cannotbe used for reliable beyond-
the-hori;on terrestrialcommunicationswithout repeatersP
a. 27 (+;
b. 1 )+;
c. 877 )+;
d. 12 H+;267. /he type of radio waveresponsible for long-distancecommunications by multiples(ips is the
a. ground wave b. direct wave
c. surface waves
d. s(y wave261. +igh-fre9uency waves are
a. absorbed by the !2layer
b. reflected by the #layer
c. capable of use for
long-distance
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communications on themoon
d. affected by the solarcycle
262. /he ionosphere has its
greatest effect on signals inwhat fre9uency range
a. 377 (+; to 3 )+;
b. 3 to 37 )+;
c. 37 to 377 )+;
d. above 377 )+;263. #istances near the s(ipdistance should be used fors(y-wave propagation
a. to avoid tilting
b. to prevent s(y-waveand upper rayinterference
c. to avoid !aradayeffect
d. so as not to e*ceedthe critical fre9uency
26$. Hround-wavecommunications is mosteffective in what fre9uencyrange
a. 377 (+; to 3 )+; b. 3 to 37 )+;
c. 37 to 377 )+;
d. above 377 )+;26. /he ionosphere causesradio signals to be
a. diffused
b. absorbed
c. refracted
d. reflected
264. +elical antenna are oftenused for satellite trac(ing at=+! because of
a. troposcatter
b. superrefraction
c. ionospheric refraction
d. the !araday effect265. A ship-to-shipcommunication system isplagued by fading. /he bestsolution seem to use of
a. a more directionalantenna
b. a broadband antenna
c. fre9uency diversity
d. space diversity266. ,t is defined as theratio of the electric fieldintensity of the reflectedwave to that of the incidentwave
a. refractive inde*
b. numerical aperture
c. reflection coefficient
d. absorption coefficient268. ,t is the measure ofenergy received per unit time0per unit area0 per unit
fre9uency interval. a. solar intensity
b. sunspot
c. solar flare
d. solar flu*287. A long period with lac(of any solar activity
a. "l iTo
b. a iTa
c. )aunder period
d. %unspots281. As a ground-wave signalmoves away from thetransmitter0 the ground waveeventually disappears due tothe
a. absorption
b. tilting
c. refraction
d. diffraction282. ,t is the lowest layer of
the atmosphere where allweather disturbances ta(esplace
a. # layer
b. %tratosphere
c. ,onosphere
d. /roposphere283. ,t is the lower limit ofthe range of fre9uencies thatprovide useful communication
between two given points bythe way of the ionosphere.
a. ):!
b. :!
c. EW!
d. ))!28$. ,t is the area that liesbetween the outer limit of theground-wave range and theinner edge of energy returnfrom the ionosphere
a. s(ip distance b. s(ip ;one
c. virtual height
d. optical hori;on28. =ariations brought aboutby the rotation of the eartharound its a*is.
a. cyclical rotation
b. seasonal variation
c. diurnal variation
d. weather variation
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284. ,onospheric irregularitycaused by solar flares0 whichare gigantic emissions ofhydrogen from the sun.
a. %udden ionospheric
disturbances b. #illenger fadeouts
c. )ogul-#elligerfadeouts
d. Any of these285. ,t is a type of fadingcaused by so-called !aradayeffect or !araday rotation
a. interference fading
b. absorption fading
c. selective fading
d. polari;ation fading286.
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d. space waves378. the ground waveeventually disappear as itmoves farther away from thetransmitter0 because of
a. tilting
b. reflection
c. refraction
d. diffraction317. as electromagnetic wavestravel in free space0 only oneof the following can happen
a. absorption
b. attenuation
c. refraction
d. reflection311. ,n polari;ationdiversity0 two signals are
a. oth polari;ed at onespecific location
b. =ertically andhori;ontally polari;edseparately
c. >olari;ed in the samemanner
d. =ertically and
hori;ontally polari;edusing a common antenna
312. ,f the direction of theelectric field of a radio waveis hori;ontal. /hat wave is(nown to be _____ polari;ed.
a. egatively
b. =ertically
c. >ositively
d. +ori;ontally
313. /he property of amaterial that determines howmuch change electrostaticenergy can be stored per unitvolume when voltage is applied
a. )iller effect
b. >ermeability
c. 'apacitance
d. >ermitivity31$. According to this law orprinciple0 a wavefront may be
considered to consist of aninfinite number of isotropicradiators0 each one sendingout wavelets0 always away fromthe source.
a. %nellGs aw
b. )a*wellGs aw
c. +uygenGs >rinciple
d. Archimedes >rinciple31. A number0 which whenmultiplied by the speed oflight in free space gives the
speed of light in the mediumin 9uestion is
a. !ibonacci number
b. !ermatGs number
c. =elocity factor
d. -factor314. /he ability of a radiowave to be bent slightly overthe edge of a sharp obstaclesuch as a steep hill ormountain top is
a. #iffraction
b.
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b. eyond the hori;onpropagation
c. "ither a or b
d.)eteoric %catter >ropagat
ion322. /he apparent height of anioni;ed layer of theatmosphereQ as determined fromthe time interval between thetransmitted signal and theionospheric echo at verticalincidence. /his height is thema*imum height reached if theactual paths are proBectedforming straight lines from
the ascent to the descent ofwaves.
a. Eptimum height
b. =irtual height
c. 'omple* height
d. 'ritical height323. /he highest fre9uencywhereby a wave will bereturned bac( to earth by anionospheric layer having beenbeamed up at it and ranges
from to 12 )+;. !or !2layers. /his fre9uency isdirectly proportional to thesecant function of thesmallest angle0 which allowsreflection of s(y waves.
a. Ape* fre9uency
b. 'ritical fre9uency
c. 'arrier fre9uency
d. aseband fre9uency
32$. /he distant at which s(y-wave signals are reflectedbac( to earth depend on
a. +eight of thereflecting layer
b. /he ta(eoff angle ofthe waves
c. oth a and b
d. 'onductivity of thesoil
32. >erfect reflection of
waves occur when a. /he magnitude of the
incident is e9ual to thereflected waves
b. /he magnitude of theincident is less than thereflected waves
c. /he magnitude ofincident is greater thanreflected waves
d. oth and b
324. /he process by which aradio wave is bent andreturned to earth from onemedium to another afterstri(ing them is
a.
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331. Atmospheric condition iscontrolled by
a. >ressure
b. /emperature
c. +umidity
d. All of these332. /his ionospheric layerforms at night at about 377 (mfrom the earthGs surface andis responsible for longdistance +! wave propagationdue to reflection andrefraction. ,t splits duringdaytime due to the ioni;ingenergy from ultraviolet raysof the sun.
a. # layer b. " layer
c. ! layer
d. =antress layer333. When the transmitting andreceiving antennas are line-of-sight of each other0 themode of propagation is _____wave.
a. %pace or direct
b. %(y c. surface
d. ground33$. >ower density isinversely proportional to thes9uare of the distance fromthe source or transmitter tothe destination or receiver./his law is calledP
a. 'oulombGs law
b. aw of :niversal
Hravitation c. ,nverse %9uare aw
d. en;Gs aw33. A one-hop0 full duple*0microwave system is in a spacediversity arrangement.#etermine how many receiversin all are used
a. 4
b. 2
c. 6 d. $
334. ________ is the e*traioni;ation of the "-layerresulting to irregular andintermittent reflection offre9uencies of up to 67 )+; intemperate and lower latitudesof fre9uencies of up to 67 )+;in temperate and lowerlatitudes. ,t is variable in
time of occurrence0 height.Heographical distribution0
penetration fre9uency andioni;ation density.
a. %poradic "
b. #illinger "ffect
c. !araday rotation
d. %cintillations335. /he decrease in signalstrength as a result ofabsorption or scattering ofenergy along a transmissionpath is calledP
a. Attenuation
b. )icrobending
c. #ispersion
d. )ultipath fading
336. /he transfer ofelectromagnetic waves oracoustical energy from oneplace to another through asuitable transmission mediumis
a. Wave propagation
b.
c.
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a. Ef the low powerre9uired
b. /he transmittingantennas are ofconvenient si;e
c. /hey are very reliable d. /hey penetrate the
ionosphere easily3$3. +igh fre9uency waves are
a. Absorbed by the !2layer
b.
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acted by an attracting orrepelling force.
a. "lectric field
b. ower density
c. )agnetic fieldintensity
d. >ermittivity ofthe medium
341. A reduction in powerdensity due to the inverses9uare law presumes free-spacepropagation is called
a. Absorption
b. Wave attenuation
c. %pace attenuation ofthe wave
d. or ' is correct342. Which of the followingare optical effects of radiowaves
a.
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34.
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b. )easures powerdensity0 voltage0 andinductance
c. )easures powerdensity0 magnetic field
intensity0 and electricfield intensity
d. All of the above354.
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c. ,ncreasing diffraction
d. #ecreasinginterference
366. What layer has itsma*imum density at
appro*imately 57 mi a noon0when the sun is at its highestpoint
a. # layer
b. " layer
c. ennelly-+eavisidelayer
d. or '368. /he sporadic " layer is athin layer with a very highioni;ation density. ,t is
considered separately from theother layers and when itappears0 gives an une*pectedimprovement in long distanceradio transmissions. WhatcauseKsL its unpredictableappearance
a. %unspot activity
b. %unspot cycle
c. %olar flares
d. A and '387. /he region in theionosphere with a very highioni;ation density at roughly to 87 miles and is used forfre9uencies up to about 27)+;. ,t is gone completely atmidnight.
a. # layer
b. " layer
c. ! layer
d. H layer381. A layer in the ionospherewhich is the most importantreflecting medium fir +! radiowaves. ,t has 2 sublayers0 at87 to 27 mi height
a. A layer
b. # layer
c. " layer
d. ! layer382. /he apparent height ofthe ioni;ed layer and isalways greater than the actualheight
a. 'ritical height
b. =irtual height
c. )a*imum height
d. ,maginary height383.
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method in which the output ofa transmitter is fed to two ormore antennas that arephysically separated by anappreciable number of
wavelengths. a. %pace diversity
b. !re9uency diversity
c. >olari;ation diversity
d. %pace wave propagation