Analysis and Design of Direct-Write Printed Antenna on Paper-Based Substrate for Flexible Displays and WLAN Application1

Ramila Sresta !"#$%&&'()lectrical )ngineeringSout Da*ota Scool of +ines and ,ecnologyRapid -ity. SD /""&'0ntroduction anantennaisanelectricaldevicewhichconvertselectricalpower into radio waves and vice versa. It is usually used with a radio transmitter or radio receiver or both. adirect-writeprintedandfexibleinverted-Fantennaona papersubstrateisdesignedforwireless localareanetwork (WLAN) and fexible displa application at !"# $%& AntennacanbeusedforWLANinterconnectivitof practicallandevicecarringafexibleornonfexible displa"'ene(ts using paper as substrate paper is an environ)entall friendl fexible )aterial" *ig*de)andandt*e)assproductionofpaper)akeit c*eapest )aterial to be used as substrate paper is an extre)el low-cost organic-based substrate for +F application paper*aslowsurfacepro(le(s)allt*icknessandlig*t weig*t ) *asgoodelectrical,dielectricperfor)anceuptoatleast1 $%& -aperasasubstrateisco)patiblewit*varioustec*nolog suc* as direct write . ink/et. copper la)ination tec*nologies assubstratefor)odern+Fdevicessuc*as+F01(+adio Fre2uenc0denti(cation1evice)tags.antennas.)icrowave (lters and )odules3ilver Nano ink for printing antenna silvernanoinkisusuallselectedtoensuregood)etal conductivit t*eseparticlesarestericallstabili&edwit*encapsulated )olecules t*ese)olecules*avetobere)ovedfro)t*ecoreof nanoparticles to )ake t*e printed antennas conductive" t*er)al sintering is one )et*od to )ake it conductive after co)pletion of printing. sintering process is used to re)ove t*e excess solvent and )aterial i)purities fro) t*e disposition conductivit of ink varies fro) 4"# to !"5x146 3,) depending on t*e te)perature and duration of t*e curing *ere. an ink wit* 748 bulk silver conductivit is used (value after 1 *our curing at 154o9) for)ation of silver ink :48bweig*toffunctionali&edsilvernanoparticleswas addedtoasolutionof;48bvolu)edistilledwaterand 148 b volu)e di-et*lene glcol t*econductiveinkis(rstultrasonicallato)i&edbefore printingFigure 1" 3canning electron )icroscope i)ages of a laer printed silver nanoparticle ink. after curing fro 15 )inutes at 144o9 (Left side) and at 154o9 (+ig*t 3ide)Losses in printed +F electronics 9onductive nanoparticle ink loss conductivit increases wit* increase in curing te)perature and varies wit* curing ti)e dielectric loss of substrate assu)ing non-)agnetic )aterial and using )icro-strip line )et*od. paper *as < r-paper=:"#and dissipation factor tan>paper=4"475 at !"#5 $%&

0nverted F-antenna(0FA) 1esign global antenna in *andset and WLAN application easil e)bedded in t*e backside of t*e laptops and )obile p*ones to be concealed for aest*etic purpose to radiate to so)e extent )ore towards t*e free-space and less in t*e user bod?s direction fexible screen re2uires fexible antenna for proper folding abilit and successful connectivit is si)ple to fabricate. bendable and can be easil fedand )atc*ed to an input port *ave o)nidirectional radiation pattern (gure !" s*ows t*e place)ent of fexible antenna onto a fexible displa screen oflaptop in a @0@A con(guration for bot*polari&ation antenna location is s*own b a dotted lines in t*e (gureFigure !"0nverted F-antenna(0FA) 1esign Figure :" 3c*e)atic design of 0FA B*e dotted line s*ows t*e ground plane in t*e backside of t*e substrate w*ile t*e solid color is )etallic laer consisting of )icro-strip feed line and antenna ground si&es is #7x!5)) )aking t*e antenna co)patible wit* s)all foldable displas and-9@90A(-ersonal9o)puter@e)or9ard0nternational Association) cards good bandwidt* is obtained b keepingclose or less t*an Cg,# t*at *elps to )aintain low side lobe level widt* w=4"56)) of feeding line produce 54D )icro-strip line" one end (wit* s di)ension) is grounded to co)pensate capacitance produced between t*e folded dipole and ground plane" anot*erendofantennaisopencircuitedto)akeinputi)pedance purel real (nal design was tested in 0E:1 software antennaprototpewasprintedin@:1(@askless@esoscale @aterial1eposition)sste)andtotalfabricationandcuringti)e was approxi)atel : *ours ten passes. eac* one depositing 4":F) t*ick were used to ac*ieve a t*ick conducting laer and to reduce t*e skin dept* eGect 0nverted F-antenna(0FA) 1esign Figure #" Final di)ension of 0FA Figure 5" 1irect-write printing of t*e antenna on paperusing @:1 )ac*ine"Figure 7" -*otograp* of 0nverted F antenna on paper substrate" Front side(Left) and back side (+ig*t)+esults of antenna )easure)ent printedantennawas)easuredwit*respecttoreturnloss311 and radiation pattern return loss was observed using Hector Network Anal&er (HNA) t*eradiationpatternofantennaatEand%-planewas )easured in t*e custo) built anec*oic c*a)ber 3!1was)easuredat!"#5$%&antennagainwascalculated usingfollowingfor)ulaw*ere-risreceivedpowerbAIB (antennaundertest)inwatts.-tistrans)ittedpowerb referenceantennainwatts.$AIBand$refaret*eAIBand referenceantennagainsrespectivel.anddisdistance between two antennas" t*e )easured )axi)u) gain is )ore t*an 1"! d'i at !"#5 $%&andt*esi)ulatedantennaeJciencisK!8.causingt*e )axi)u)gainvaluetobe1d'lesst*ant*eantenna?s )axi)u) directivit Figure 6" 3i)ulated and )easured return loss of 0FA on paper t*e )easured resonant fre2uenc was !"5$%& w*ic* was /ust !8 s*ift fro) t*e si)ulated" antenna *as -14db bandwidt* ofLf 'W=!#8 w*ic* covers suJcientl WLAN fre2uenc rangeFigure K" @easured and si)ulated radiation pattern of 0FA antenna on paper at !"#5 $%& at E-plane(a) and %-plane(b)Flexibilit test of antennaFigure ;" -*otograp* of fabricated 0FA on paper. bended around t*e clindrical structure wit* diGerent radii" t*e antenna s*owed no sign of per)anent defor)ation. conductivit deterioration or ink detac*)ent after extensive and repeated bending-onclusion paper based inverted F antenna for WLAN application was fabricated and )easured at !"#5 $%& t*e antenna di)ension is co)patible to be used in -9@90A (-ersonal 9o)puter @e)or 9ard 0nternational Association) cards t*e antenna s*owed ver good return loss and radiation pattern can be easil bended to incorporate in a fexible displa of a portable devices ( laptop. )obile p*ones ) 1espite t*e relativel *ig* dielectric loss of paper substrate t*e )easured )axi)u) gain is )ore t*an 1"! d'i at !"#5 $%&and t*e si)ulated antenna eJcienc is K!8Future Workdevelop)ent of printed antenna forsecurit and wireless application using direct-write tec*nolog Muestions