2 Marks With Answer

7/22/2019 2 Marks With Answer

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OM SAKTHIADHIPARASAKTHI COLLEGE OF ENGINEERING

G.B.NAGAR, KALAVAI 632 506DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING

SUB CODE&NAME: EC2353 ANTENNA&AVE PROPAGATION

UNIT I ELECTROMAGNETIC RADIATION AND ANTENNA FUNDAMENTAL

!. D"#$%" %'"%%.Antenna is a conductor having a length of /2 (or) Antenna is a transducer which converts

electrical to electromagnetic wave (or) Antenna is a impedance matching circuit between

transmission line and free space.

2. (' $) *"%' + -$'$/% ''"-%1Radiation pattern is graphical representation of radiation and it provides spatial distribution of

radiated energy of the source with respect to angle. It is classified into two types

i) Field Pattern

ii) Power Pattern

3. D"#$%" P/"- P''"-%.If the radiation pattern is drawn as radiation in terms of power with respect to angle than it is

called power pattern.

. (' $) *"%' + #$"4 ''"-%1If the radiation pattern is drawn as radiation in terms of Voltage (Field ) with respect to angle

than it is called power pattern.

5. D"#$%" R$'$/% $%'"%)$'.he power radiated from an antenna per unit solid angle is called the radiation intensity. It is

denoted by !he unit of radiation intensity is watts " steridians (or) watts " radian#

It is given by

! $ %radR#

%rad & Radiation 'ensity

R &'istance

6. D"#$%" H"-'$% $/4".%hen the antenna length () is very very small compare to wavelength ( * ) than it is called

+ert,ian dipole (or) -mall current element (or) scillating dipole (or) elementary dipole.

2 MARKS QUESTION WITH ANSWER


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. D"#$%" 7"8'/- /'"%'$4.he magnetic vector potential or simply vector potential is denoted by a vector A. it potential due to

the charges in a small current element

9. (' $) *"%' + -"'-" V"8'/- /'"%'$41he magnetic Vector potential A is called Retarded Vector Potential when it is delayed due to time

varying current at distance point from the element then it is given by

A(t&r"c) $ A(t / t0) $

. D"#$%" I)/'-/$8 A%'"%%.An isotropic antenna radiates e1ual radiation in all directions the radiation pattern of isotropic antenna

is li2e a sphere . it is also called as point source

!0. D"#$%" B"* "##$8$"%8.he ratio of the main beam area (34) to the total beam area (3A) is called beam efficiency denoted

as ;MB"* "##$8$"%8 $) $)/'-/$8 %'"%%?

!. (' $) P/"-


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!5. D"#$%" B"* $'(.Antenna beam width is a measure of sharpness of the main radiation ( main beam) Antenna beam

width is an angular width in degrees7 measured on the radiation pattern ( ma:or lobe)

hey are two different ;eam width

+P;% / +alf power ;eam width

F=> times of its ma5imum value in field pattern.

!. (' $) *"%' + F$-)' N@44 B"* $'( >FNB? 1First


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D / is Duality factor

2!. S''" R"8$-/8$' '("/-"*.he reciprocity theorem for antenna is stated as if a current ICat the terminals of antenna no. C

induces an emf @#Cat the open terminals of antenna no.# and a current I#at the terminals of antenna

no.# induces an emf @#Cat the open terminals of antenna no.C then

@#C $ @#C Provided IC $ I#

with -ame fre1uency E same medium.

22. D"#$%" E##"8'$7" A"-'@-".It is defined as the ratio of power received at the antenna to the power density of the incident wave

A" = P- S P- R"8"$7" /"-

S P/"- D")%)$'.

23. (' $) *"%' + "##"8'$7" 4"%/-? H"-'$% D$/4" >/-? O)8$44'$%< $/4" >/-?"4"*"%'- $/4".

%hen the antenna length () is very very small compare to wavelength ( * ) than it is called

+ert,ian dipole (or) -mall current element (or) scillating dipole (or) elementary dipole.
http://en.wikipedia.org/wiki/Antenna_(electronics)http://en.wikipedia.org/wiki/Radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Antenna_(electronics)http://en.wikipedia.org/wiki/Radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiation


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3. -$'" '(" R$'$/% R")$)'%8" V4@" /# F-"" )8", S(/-' D$/4" H4# 7" D$/4" %M/%/ P/4"1Free space $ G>>3 (or ) C#=H 3

-hort 'ipole $ = H#( l" *)#3

+alf %ave 'ipole $ >G 3

4ono Pole $ GJ.K 3

. D"#$%" (4# 7" $/4".

Any linear antenna of *" # long is called as half wave dipole antenna or Resonant length antenna

5. D"#$%" @-'"- 7" */%//4".

Any linear antenna of *" L long is called as Duarter wave monopole antenna

6. D"#$%" $-" A%'"%%).%ire antennas are made of thin7 conducting straight or curved wire segments or hollow tubes. hey

are very easy to construct. he dipole and monopole antennas are e5amples of straight wire

antennas. he loop antenna is an e5ample of a curved wire antenna.

. (' $) *"%' + 4// %'"%%1he loop antenna is a radiating coil of any convenient cross section of one or more turns carrying

RF currents.

he different shapes of loop antennas are

R"8'%


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!+F transmitters

!!. (' $) *"%' + A%'"%% A--1An antenna array is a system of similar antenna oriented similarly to get greater directivity in a

desired direction

!2. D"#$%" U%$#/-* L$%"- A--.A uniform inear Array is one in which the elements are fed with a current of e1ual magnitude

with uniform phase shift along the line

!3. (' $) B-/ )$" -- % - $') -$'$/% ''"-%1he ;road side array is one in which a number of identical parallel antenna are arranged in e1ual

spacing and feed with e1ual amplitude and same phase so that the ma5imum radiation in broad

side of the array.

!. (' $) E% #$-" -- % - $') -$'$/% ''"-%1he @nd Fire array is one in which a number of identical parallel antenna are arranged in e1ual

spacing and feed with e1ual amplitude and out off phase ( !sually C=M ) so that the ma5imum

radiation in the direction of ends of Antenna array.

!5. D"#$%" C/4$%"- A--Antennas are mounted end to end in single line (or) one antenna stac2ed over another antenna as

shown in figure is called collinear array

!6. (' $) *"%' P()" D$##"-"%8"1I' $) ()" $##"-"%8" /# '(" 7" +"'""% '(" '/ /$%') % $' $)


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!9. D"#$%" -- #8'/-.

he factor by which the array increases the field strength over that of a single element radiating the

same total power.

!. (' $) *"%' + B$%/*$4 A--o reduce the side lobe level the antenna are feeded with amplitude proportional to the co&

efficient of a binomial series of the form

>+?%!= %2 >%!?%2 + >%!?>%2?%3+2! 2

%here n is the number of antennas.

20. D"#$%" N/% U%$#/-* $)'-$+@'" A--.o reduce the side lobe level the antenna are feeded with different amplitude (non !niform) @g.

;inomial Array.

2!. (' -" '(" 7%'M

@dge CKM

2. (' $) P()" --1he Phased array is one in which a number of identical parallel antenna are arranged in e1ual

spacing and feed with e1ual amplitude and Progressive phase shift.

25. L$)' )/*" /# '(" 7%'


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UNIT III APERTURE ANTENNAS

!. D"#$%" M


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!2. ( '-%)/)$%< 4$%" $) %"" $% LPA1!3. (' $) "##"8') /# "8-")$%< '(" $% LPDA1!. (' $) *"%' + T@-%)'$4" %'"%%1!5. (' $) *"%' + B$8/%$84 %'"%%1!6. L$)' /@' )/*" #-"@"%8 $%""%"%' %'"%%1!. (' $) *"%' + H"4$84 %'"%%1!9. (' -" '(" '") /# -$'$/% */") /# /"-'$/% #/- ("4$84 %'"%%1!. D- '(" -$'$/% ''"-% /# A$4 */" % %/-*4 */" /# ("4$ %'"%%120. L$)' '(" 4$8'$/%) /# ("4$84 %'"%%12!. N*" % )"'8( % %'"%% ($8( -/7$") 8$-8@4-4 /4-$" 7")122. (' $) -(/*+$8 %'"%% %

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