MCQ's Radiowave Propagation

7/23/2019 MCQ's Radiowave Propagation

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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


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


10/33

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


12/33

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.


14/33

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


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


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


16/33

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


18/33

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.


19/33

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


20/33

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.


21/33

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


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


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.


22/33

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


23/33

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


24/33

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.


25/33

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.


26/33

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.


27/33

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.


28/33

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.


29/33

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.


30/33

34.


31/33

b. )easures powerdensity0 voltage0 andinductance

c. )easures powerdensity0 magnetic field

intensity0 and electricfield intensity

d. All of the above354.


32/33

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.


33/33

method in which the output ofa transmitter is fed to two ormore antennas that arephysically separated by anappreciable number of

wavelengths. a. %pace diversity


c. >olari;ation diversity

d. %pace wave propagation

MCQ's Radiowave Propagation

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