Technische Universität Chemnitz Fakultät für Elektrotechnik und Informationstechnik Professur Hochfrequenztechnik und Theoretische Elektrotechnik
Masters esearch Pro!ect
I"#E$TI%&TE THE I"F'UE"CE (F )IFFEE"T T*PE$ (F FEE)$ (" THE PEF(M&"CE PEF( M&"CE (F & ECT&"%U'& ECT&"%U'& P&TCH P&TCH &"TE""& &"T E""&
Pro!ect %uide
+ Prof, )r,-In., ha/il, Madhu Chandra
Submitted By
: Pavan Kumar Akula
Matri atricu cullati ation Numbe umberr
: 3891 389187 87
Coure
: !n"ormation and Communication Sytem
#e$ree
: Mater
&/stract+ Introduction+ !n %i$%&'er"ormance aircra"t( 'acecra"t( atellite etc)( *%ere i+e( *ei$%t( cot 'er"ormance and eae o" intallation are contraint( lo* 'ro"ile antenna may be re,uired) Patc% Antenna meet t%i re,uirement) Patc% Antenna alo called a Microtri' Patc% Antenna are lo* cot( eaily "abricated( and are con"ormable to 'lanar and co'lanar ur"ace) -%e !m'edance and 'olari+ation 'attern in t%ee Antenna can be dei$ned by %avin$ additional load bet*een 'atc% and $round 'lane uc% a 'in( varactor diode) .it% t%e current tate o" art uin$ modern 'rinted&circuit tec%nolo$y( mec%anically robut *%en mounted on ri$id ur"ace( com'atible *it% current Monolit%ic Micro*ave !nte$rated Circuit /MM!C0 tec%nolo$y) Alon$ *it% t%e above mentioned advanta$e( t%ere are ome diadvanta$e alo t%at eit) Some o" t%e main diadvanta$e are 2o* e""iciency( 2o* 'o*er( i$% 4 /ometime 51660( and Narro* "re,uency band&*idt%) -%e e""iciency and band&*idt% can be im'roved by increain$ t%e %ei$%t o" ubtrate 1) #ue to t%i increae in %ei$%t( ur"ace *ave are introduced t%at can etract 'o*er "rom direct radiation *%ic% i not deirable) -%ee *ave $et cattered at t%e ed$e o" t%e ubtrate and ur"ace dicontinuity occur by de$radin$ t%e 'attern and c%aracteritic o" Antenna) -%ee *ave can be eliminated by introducin$ cavitie and tackin$ by maintainin$ lar$e band*idt% 3) -%e Patc% Antenna conit o" a very t%in metallic tri' above t%e $round 'lane *%ere it t%ickne /t0 %ould be "ree&'ace *avelen$t%)
Pro0osed Investi.ation+ -o imulate and analy+e t%e 'er"ormance o" a ;ectan$ular Patc% Antenna "or a $iven deired "re,uency o" 3 <+ by uin$ tandard and 'o'ular "eed like Microtri' line( Coaial 'robe( A'erture cou'lin$ and Proimity cou'lin$ "eed by eaminin$ variou 'arameter like radiation 'attern(
*%ic% $enerally occur *%ile imulatin$ t%e Microtri' Antenna uin$ -ranmiion&2ine model) .e be$in *it% t%i eaier illutrative model in t%e initial ta$e( imulate and undertand it 'er"ormance) 2atter in t%i re'ort( t%e conce't o" Cavity model i introduced "or *%ic% Patc% Antenna reonate in %i$%er order and reemble dielectric loaded cavitie >) Alo *e *ill undertand t%e '%yical inter'retation o" t%e "ormation o" t%e "ield *it% in t%e cavity due to *%ic% t%e c%ar$e ditribution i controlled uin$ attractive and re'ulive mec%anim)
Method Used+ 10 -o develo' a ) 30 -%e eecution o" t%e t%eory *ill be done via MA-2AB( uin$ t%e conce't o" ;outine in order to $enerate t%e out'ut 'arameter and imulated uin$ Ano"t SS)
esults+ 10 -o imulate t%e dei$ned Antenna uin$ Ano"t SS and decide t%e bet "eed baed on t%e reult obtained uin$ SS) 0 -o com'are and contrat t%e imulated radiation 'attern o" t%e variou "eed o" Antenna)
Conclusion+ !n t%e "irt '%ae i)e)( ;eearc% 'ro=ect '%ae( a
T&1'E (F C("TE"T$ CH&PTE "(, TIT'E &1$T&CT 'I$T (F FI%UE$ 2 I"T()UCTI(" 2,2 3H&T M&4E$ & %(() &"TE""& 2,5 3(4I"% (F & P&TCH &"TE""& 2,6 )E$I%" P&&METE$ 2,7 METH() (F &"&'*$I$ 2,7,2 T&"$MI$$I("-'I"E M()E' 2,8 )E$I%" 5 FEE)I"% METH()$ 5,2 C(&9I&' FEE)
P&%E "(,
2 2 2 5 5 5 7 8 8
'I$T (F FI%UE$ FI%UE "(, TIT'E 1)1 Frin.in. effects alon. len.th of Patch 1) Ph:sical and effective len.ths of rectan.ular microstri0 0atch
P&%E "(, 6 7
)1
To0 vie; of a t:0ical microstri0 antenna ;ith coa<
8
)
feed $ide vie; of a t:0ical microstri0 antenna ;ith coa<
8
feed
'I$T (F T&1'E$ T&1'E "(, 1)1
TIT'E 'ist of In0ut Parameters
P&%E "(, 5
CH&PTE 2 I"T()UCTI(" Introduction+ Microtri' antenna %ave been one o" t%e mot innovative to'ic in antenna t%eory and dei$n in recent year( and are increain$ly "indin$ a''lication in a *ide ran$e o" modern micro*ave ytem) -%e baic con"i$uration o" a microtri' antenna i a metallic 'atc% 'rinted on a t%in( $rounded dielectric ubtrate) ri$inally( t%e element *a "ed *it% eit%er a
coaial line t%rou$% t%e bottom o" t%e ubtrate( or by a co'lanar microtri' line) -%i latter ty'e o" ecitation allo* "eed net*ork and ot%er circuitry to be "abricated on t%e ame ubtrate a t%e antenna element( a in t%e cor'orate&"ed microtri' array) !t radiate a relatively broad beam broadide to t%e 'lane o" t%e ubtrate) -%i t%e microtri' antenna %a a very lo* 'ro"ile( and can be "abricated uin$ 'rinted circuit /'%otolit%o$ra'%ic0 tec%ni,ue) -o a lar$e etent( t%e develo'ment o" microtri' antenna %a been driven by ytem re,uirement "or antenna *it% lo*&'ro"ile( lo*&*ei$%t( lo*&cot( eaily inte$rability into array or *it% micro*ave inte$rated circuit( or 'olari+ation diverity) #iadvanta$e o" t%e ori$inal microtri' antenna con"i$uration include narro* band*idt%( 'uriou "eed radiation( 'oor 'olari+ation 'urity( limited 'o*er ca'acity( and tolerance 'roblem) Muc% o" t%e develo'ment *ork in microtri' antenna %a t%u $one into tryin$ to overcome t%ee 'roblem( in order to ati"y increain$ly trin$ent ytem re,uirement 1)
2,2 3hat makes a .ood antenna= >8? A0 ne in$le an*er *ould be: resonant, An ob=ect may '%yically reonate & e)$) a 'iano trin$( or a $uitar trin$) ac% o" t%oe muical intrument %a a trin$ t%at i eit%er truck or 'lucked & and t%e trin$ '%yically vibrate at one 'eci"ic "re,uency) An antenna i imilar in many *ay to t%at muical trin$) !t reonate bet at one 'articular "re,uency) !t can reonate a little above and belo* t%at "re,uency( and ometime at multi'le o" t%at "re,uency( but it uually doe bet at t%at one "re,uency)
2,5 3orkin. of a Patch &ntenna+ .%en t%e 'atc% i ecited by a "eed( a c%ar$e ditribution i etabli%ed on t%e underide o" t%e 'atc% metalli+ation and t%e $round 'lane) At a 'articular intance o" time( t%e underide o" t%e 'atc% i 'oitively c%ar$ed and t%e $round 'lane i ne$atively c%ar$ed) -%e attractive "orce bet*een t%ee et o" c%ar$e tend to %old a lar$e 'ercenta$e o" t%e c%ar$e bet*een t%e t*o ur"ace) o*ever( t%e re'ulive "orce bet*een 'oitive c%ar$e on t%e 'atc% 'u%e ome o" t%ee c%ar$e to*ard ed$e( reultin$ in lar$e c%ar$e denity at ed$e D) -%e dielectric Subtrate i uually electrically t%in /d 6)6E F 60( o electric "ield com'onent 'arallel to t%e $round 'lane mut be very mall t%rou$%out t%e ubtrate) -%e 'atc% element reonate *%en it len$t% i near FG( leadin$ to relatively lar$e current and "ield am'litude) !n t%e vie* o" e,uivalence t%eorem( t%ere are everal *ay to inter'ret t%e reultin$ radiation) Alternatively( radiation can be conidered a bein$ $enerated by t%e induced ur"ace current denity( on t%e 'atc% element in t%e 'reence o" t%e $rounded dielectric ubtrate 1) -%ere are numerou ubtrate t%at can be ued "or t%e dei$n o" microtri' antenna( and t%eir dielectric contant are uually in t%e ran$e o" ) @r 1) -%e one t%at are mot deirable "or antenna 'er"ormance are t%ick ubtrate *%oe dielectric contant i in t%e lo*er end o" t%e ran$e becaue t%ey 'rovide better e""iciency( lar$er band*idt%( looely bound "ield "or radiation into t%e 'ace( but at t%e e'ene o" lar$er element i+e)
2,6 )esi.n Parameters+ >@?
-%e "ollo*in$ are ome "eature o" ;o$er ;-G#uroid E886) !t %a lo* moiture abor'tion( iotro'ic in nature( uni"orm electrical 'ro'ertie over "re,uency and ecellent c%emical reitance) -%e dielectric contant o" t%i material i uni"orm "rom 'anel to 'anel and i contant over a *ide "re,uency ran$e) !t lo* dii'ation "actor etend to ue"ulne to Ku& band and above) -able 1)1 %o* variou in'ut 'arameter to conider "or imulatin$)
Ta/le 2,2+ 'ist of In0ut Parameters ;eonant re,uency #ielectric Subtrate #ielectric Contant o" Subtrate/@r 0 ;eonatin$ ;eitance /; r0 ei$%t o" Subtrate
A,B %Hz o.ers T)uroid 8BBD 5,5 8D 2,8@8 mm
2,7 Method of &nal:sis+ >7? -%ere are many met%od o" analyi o" microtri' antenna) -%e mot 'o'ular model are t%e tranmiion&line and cavity model) Amon$t tranmiion&line model i eaiet o" all( it $ive $ood '%yical ini$%t( but i le accurate and it i more di""icult to model cou'lin$)
2,7,2 Transmission-'ine Model Baically t%e tranmiion line model re'reent t%e microtri' antenna by t*o lot e'arated by a lo*&im'edance H 6 tranmiion line o" 2en$t% 2) -%e antenna i vie*ed a a len$t% o" o'en&circuited tranmiion line *it% li$%t loadin$ at t%e end to account "or "rin$in$ "ield and radiation *%ic% i e'lained belo*) -%e volta$e and current on t%i e,uivalent tranmiion line can be a''roimated a 1: πX
Iolta$e J I/0 J I6
cos
V 0
Current J ! /0 J
Z 0
L
sin
πX L
a Frin.in. effects+ Becaue t%e dimenion o" t%e 'atc% are "inite alon$ t%e len$t% and *idt%( t%e "ield at t%e ed$e o" t%e 'atc% under$o "rin$in$) -%i i illutrated alon$ t%e len$t% in t%e i$ure 1 "or t%e t*o radiatin$ lot o" t%e microtri' antenna) -%e ame a''lie alon$ *idt%) Mot o" t%e electric "ield line reide in t%e ubtrate and 'art o" ome line eit and 'art o" ome o" line in air) !" t%e ratio o" *idt% and %ei$%t i $reater 1 and dielectric contant i $reater t%an 1( t%en t%e electric "ield line concentrate motly in t%e ubtrate) rin$in$ in t%i cae make t%e microtri' line look *ider electrically com'ared to it '%yical dimenion) Since ome o" t%e *ave travel t%rou$% ubtrate and ome in air( an e""ective dielectric contant /@e"" 0 i introduced to brin$ "rin$in$ and t%e *ave 'ro'a$ation in t%e line) or
mot o" t%e a''lication e""ective dielectric contant %a value in t%e ran$e o" 1 @e"" @ r near
to t%e value o" ori$inal dielectric contant)
Fi. 2,2+ Frin.in. effects alon. len.th of Patch, -%e e""ective dielectric contant i a "unction o" "re,uency) A t%e "re,uency o" o'eration increae( mot o" t%e electric "ield line concentrate in t%e ubtrate) or lo*er "re,uencie t%e e""ective dielectric contant i eentially contant) At intermediate "re,uencie it value be$in to monotonically increae and eventually a''roac% to t%e value o" dielectric contant o" t%e ubtrate) -%ere"ore t%e e""ective dielectric contant i $iven by
*%ere . i t%e *idt% o" t%e 'atc% *%ic% can be calculated uin$ t%e belo* "ormula and @r in our cae i ) and t%e *idt% o" t%e 'atc% i $iven by
.%ere C i t%e velocity o" li$%t *%ic% i 316 8 MGSec and " 6 i t%e reonant "re,uency *%ic% on our cae i 9)8 <+)
/ Calculation of Effective 'en.th Becaue o" t%e "rin$in$ e""ect( electrically t%e 'atc% o" t%e microtri' antenna look $reater t%an it '%yical dimenion) or t%e 'rinci'al demontrated *%ere t%e dimenion o" t%e 'atc% alon$ it len$t% %ave been etended on eac% end by a ditance L2( *%ic% i "unction o" e""ective dielectric contant and t%e *idt%&to&%ei$%t ratio)
Fi. 2,5+ Ph:sical and effective len.ths of rectan.ular microstri0 0atch,
A very 'o'ular and a''roimate relation "or normal etenion o" len$t% i
Since t%e len$t% o" t%e 'atc% %a been etended by L2 on eac% ide( t%e e""ective len$t% o" 'atc% i no* 2e"" J 2 L2 And 2en$t% o" Patc% i $iven by λ
2 J
2
2,8)esi.n+ Baed on t%e im'li"ied "ormulation t%at %a been decribed( a dei$n 'rocedure i outlined *%ic% lead to 'ractical dei$n o" ;ectan$ular Microtri' Antenna) In0uts to /e s0ecified+ @r ( " r /in <+0 and % /in cm0) Parameters to determine+ .( 2
Procedure+ 2 or an e""icient radiation( a 'ractical *idt% *ould lead to better 5 6 7 8
e""iciencie) #etermine t%e e""ective #ielectric Contant /@re"" 0) nce . i "ound( determine t%e etenion len$t% L2) -%en obtain t%e actual len$t% o" Patc% 2) or 'ractical conideration( *e %ave to conider t%e "ollo*in$ $round 'lane dimenion "or imulation i)e)( 2$ J D% 2 and .$ J D% .)
CH&PTE 5 FEE)I"% METH()$ !n t%i c%a'ter( *e *ill $o t%rou$% variou ty'e o" "eed t%at %ave been 'reent and t%eir c%aracteritic) An antenna need an in'ut to %o* it 'er"ormance c%aracteritic *%ic% can
be done t%rou$% t%ee "eedin$ met%od) -%ere are many con"i$uration t%at can be ued to "eed microtri' antenna) -%e "our mot 'o'ular are t%e Microtri' 2ine( Coaial Probe( a'erture cou'lin$ and Proimity Cou'lin$) Selection o" t%e "eedin$ tec%ni,ue $overned by a number o" "actor) -%e mot im'ortant conideration i t%e e""icient tran"er o" 'o*er bet*een t%e radiatin$ tructure and "eed tructure( t%at i( im'edance matc%in$ bet*een t%e t*o) Minimi+ation o" 'uriou radiation and it e""ect on t%e radiation 'attern i one o" t%e im'ortant "actor "or t%e evaluation o" "eed D)
5,2 Coa
Fi. 5,2 To0 vie; of a t:0ical microstri0 antenna ;ith coa< feed
Fi. 5,5 $ide vie; of a t:0ical microstri0 antenna ;ith coa< feed A %o* in "i$ )( t%e coaial connector i attac%ed to t%e back ide o" t%e 'rinted circuit board( and t%e coaial center conductor a"ter 'ain$ t%rou$% t%e ubtrate i oldered to t%e 'atc% metalli+ation) -%e location o" "eed 'oint i determined "or t%e $iven mode o t%at t%e bet im'edance matc% i ac%ieved) -%e outer core dimenion o" t%e coaial cable %ould be inner core diameter) Coaial 'robe "eed %a t%e advanta$e o" im'licity o" dei$n t%rou$% t%e 'oitionin$ o" t%e "eed 'oint to ad=ut t%e in'ut im'edance level) But it %a everal limitation) or increaed band*idt% o" Patc% antenna( a t%icker ubtrate i ued and t%ere"ore re,uire a lon$er 'robe) -%i $ive rie to an increae in 'uriou radiation "rom 'robe( increaed ur"ace 'o*er and increaed "eed inductance) o*ever "eed inductance can be com'enated by a erie o" ca'acitor D)
5,5 Microstri0 feed A tri'line or tri'late device i a and*ic% o" three 0arallel conductin. la:ers e'arated by t;o thin dielectric su/strates ( t%e center conductor o" *%ic% i analo$ou to t%e center conductor o" a coaial tranmiion line) !n contrat to t%i( a microtri' device i t%e im'let "orm *%ic% conit o" a and*ic% o" t;o 0arallel conductin. la:ers e'arated by a sin.le thin dielectric su/strate 8) -%e "irt conductin$ layer i t%e lo*er conductor *%ic% act a a $round 'lane and t%e econd layer i t%e u''er conductor *%ic% i a im'le rectan$ular 'atc% and t%e aociated "eed net*ork) -%e cou'lin$ bet*een t%e microtri' line and t%e 'atc% could be in t%e "orm o" ed$e or t%rou$% a $a' bet*een t%em D) !n t%i ty'e o" "eed tec%ni,ue( a conductin$ tri' *%ic% i maller in *idt% *%en com'ared to t%e 'atc% i connected directly to t%e ed$e o" Microtri' Patc% a %o*n i "i$ )3) o*ever a t%e t%ickne o" t%e dielectric ubtrate bein$ ued( increae 'uriou "eed radiation *%ic% decreae t%e antenna band*idt% and introduce undeired cro 'olari+ed radiation) -%i can be reduced by o'timi+in$ t%e a'ect ratio .G2 o" t%e 'atc% at about 1)E D) -%i met%od i advanta$e due to it im'le tructure) -%e ed$e cou'led "eed decribed u""er "rom a limitation on im'edance mimatc% becaue t%e in'ut im'edance o" t%e 'atc% at it radiatin$ ed$e i very %i$% com'ared to t%e E6 ) -%ere"ore( an eternal im'edance matc%in$ circuit i ued bet*een t%e 'atc% ed$e and t%e E6 microtri' line) !n t%e direct microtri' "eed( t%e "eed 'oint i elected on t%e non&radiatin$ ed$e o" t%e 'atc%)
Fi. 5,6 Patch &ntenna ;ith Microstri0 Feed
eferences+ 1) Po+ar( #avid M)( OMicrotri' Antenna(O Proceedings of the IEEE ( vol)86( no)1( '')79 & 91( an 199) ) 2ier( )Q akoben( K)( O;ectan$ular microtri' 'atc% Antenna *it% in"inite and "inite $round 'lane dimenion(O Antennas and Propagation, IEEE Transactions on ( vol)31( no)D( '')978 & 98>( Nov 1983) 3) 2on$( S)A)Q .alton( M)( OA dual&"re,uency tacked circular&dic antenna(O Antennas and Propagation, IEEE Transactions on ( vol)7( no)( '')76&73( Mar 1979) >) Balani( Contantine A( OAntenna -%eory: Analyi and #ei$n(O nd ed)( 199( o%n .iley R Son( !nc)( '') 77&7E)
E) %tt':GG***),l)netGaa6niGantenna"a,)%tml( 6>t% uly( 61E) D) ;ame% ( an 1981)
