application of fft in phased array antenna (1)

7/23/2019 Application of Fft in Phased Array Antenna (1)

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APPLICATION OF FFT IN

PHASED ARRAY ANTENNA

Prof.Dr.V.Prithviraj

PrincipalRIT



N!ar "!l# an# Far "!l#

$!a%&r!$!nt%

• Th! n!ar"!l# t!%t %'%t!$ $!a%&r!% th! !n!r(' in th! ra#iatin(n!ar"!l# r!(ion an# conv!rt% tho%! $!a%&r!$!nt% )' a Fo&ri!rtran%for$ into th! far"!l# r!%&lt.

• Th! ra#iatin( n!ar"!l# r!(ion !*t!n#% fro$ th! r!activ! r!(ion)o&n#ar' o&t to a #i%tanc! #!"n!# a%+ ,D--,La$)#a /ith D

)!in( th! lar(!%t #i$!n%ion of th! ant!nna ap!rt&r!+ an# La$)#a)!in( th! /av!l!n(th.

• 0!'on# thi% #i%tanc! i% th! far"!l# r!(ion /h!r! th! an(&lar#i%tri)&tion of th! !n!r(' #o!% not var' /ith #i%tanc!+ an# th!po/!r l!v!l #!ca'% accor#in( to th! inv!r%! %1&ar! la/ /ith

#i%tanc!.• Th! %i2! of th! $!a%&r!$!nt ar!a i% i$portant /h!n con%i#!rin(

th! acc&rac' of th! planar n!ar"!l# $!a%&r!$!nt t!chni1&!. Th! %!con# #ia(ra$ %ho/% an ant!nna &n#!r t!%t an# a on!#i$!n%ional vi!/ of a "nit! %i2!# planar $!a%&r!$!nt ar!a.



NEAR FIELD 3 FAR FIELD

4EAS5RE4ENTS



• Th! %i2! of th! ant!nna &n#!r t!%t an# th! %i2! an#

location of th! "nit! $!a%&r!$!nt ar!a #!"n! th! critical

an(l! 6.• Th! calc&lat!# far"!l# patt!rn of th! ant!nna /ill )!

acc&rat! in th! r!(ion )!t/!!n 76. Co$pl!t! an(&larcov!ra(! can )! o)tain!# in th! %ph!rical %'%t!$ )'p!rfor$in( n!ar"!l# $!a%&r!$!nt% ov!r th! co$pl!t!

%ph!rical n!ar"!l# %&rfac!.

• Critical an(l!% of a)o&t 89 #!(r!!% can )! o)tain!# &%in( aplanar %&rfac! locat!# t/o /av!l!n(th% fro$ th! ant!nnaan# ov!r%cannin( th! ant!nna ap!rt&r! )' a)o&t %i*/av!l!n(th% on !ach %i#!.

• Th&% th! $!a%&r!$!nt ar!a for hi(h (ain $icro/av! an#$$/av! ant!nna%+ if li$it!# an(&lar cov!ra(! i% n!!#!#+i% not $&ch lar(!r than th! ap!rt&r! of th! ant!nna.



N!ar"!l# Con"(&ration%

• PLANAR

• CYLINDRICAL

•

SPHERICAL



PLANAR



PLANAR

• In thi% "(&r! a planar n!ar"!l# t!%t%!t&p i% %ho/n. Th! ant!nna &n#!rt!%t i% $o&nt!# in a %tationar'

fa%hion :thi% i% on! of th! $aina#vanta(!% of thi% t'p! of t!%tin(;an# th! n!ar"!l# pro)! i% $ov!#

alon( a planar %&rfac! in )oth < an# Y #ir!ction% %o that a (ri# of "!l#%a$pl!% can )! ta=!n.



CYLINDRICAL



SPHERICAL



ANTENNA TYPE/ PARAMETER PLANAR

High-gain antennas !*c!ll!nt

Low-gain antennas poor

Stationary AUT '!%

Zero-gravity Stim!ation !*c!ll!nt

A!ignment Ease %i$pl!

S"ee# fa%t



N!ar"!l# Ant!nna 4!a%&r!$!nt%

• In >??> Dan Slat!r /rot! aco$pr!h!n%iv! )oo= titl!# @N!arFi!l# Ant!nna 4!a%&r!$!nt%@ a)o&t

th! !$!r(in( ant!nna $!a%&r!$!ntt!chni1&! =no/n a% n!ar"!l#$!a%&r!$!nt%.



• N!ar"!l# $!a%&r!$!nt% al%o provi#! th! n!c!%%ar'infor$ation to #!t!r$in! th! ra#iatin( "!l# at th! %&rfac! ofth! ant!nna. Thi% proc!%% i% call!# $icro/av! holo(raph'an# involv!% )ac= tran%for$ation of th! n!ar"!l#$!a%&r!$!nt.

• 0ac= tran%for$ation i% po%%i)l! in all thr!! n!ar"!l#%'%t!$%. Th! &%! of th! )ac= tran%for$ation ha% it%(r!at!%t application in th! pha%! ali(n$!nt of pha%!#arra'ant!nna%.

• Th! a$plit&#! an# pha%! of !ach !l!$!nt of a pha%!# arra'can )! #!t!r$in!# acc&rat!l' an# i% &%!# to a#j&%t th!pha%! of th! !l!$!nt+ an# to #!t!ct #!f!ctiv! !l!$!nt% orpha%! %hift!r%. El!$!nt pha%! acc&rac' of on! #!(r!! R4S

i% )!in( achi!v!# on lar(! $icro/av! ra#ar ant!nna%.

• Oth!r &%!% incl&#! th! #!t!ction of ano$ali!% inran#o$n!%% an# in #!t!ction of %&rfac! #i%tortion inpara)olic r!!ctor ant!nna%.

application of fft in phased array antenna (1)

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