Air gap aperture coupled stacked patch antenna for dual-band

Transcription

1 Ai ga aetue couled stacked atc antenna fo dual-band Rajes Kuma Viswakama, Sanjay Tiwai Deatment of ECE, JUET, Ragoga, Guna Scool of Studies in Electonics, Pt. Ravisanka Sukla Univesity Raiu Abstact-Micosti antennas (MAS) ae vey useful antenna wee low ofile antennas ae equied. Tey ae most oula due to tei small size, low cost, ligt weigt. Te fist aetue couled micosti antenna was intoduced in 985 by D M Poza. Aetue couled antenna is a aticula antenna wit ig gain and wide bandwidt. Tis ae esents aetue couled stacked atc antenna using ai ga vaiation. Te vaiation of ai ga [mm to 6mm] as been done between single atc antenna and an aetue couled antenna. Te main advantage of tis antenna to incease te band widt of te antenna as comaed wit single layeed atc antenna. Te esonant fequencies canges wit ai ga vaiations. Te feed can be done eite a conventional coaxial obe o toug a couling aetue in te gound lane as we done. Tis antenna woks well in te fequency ange (.9 GHz to 6.0 GHz). Te measued etun loss exibit an imedance bandwidt of 35%.Te inut imedance and VSR etun loss ave been measued wit te el of Netwok analyze. [Agilent E8363B A.04.06] Fom te measued esult it is found tat te value of VSR coesonding lowe esonance fequencies inceases fom 4 to. wit inceasing ai ga vaiation wee as at te ue esonance fequencies is also inceased fom.8 to.3. Key wods: Aetue couled micosti antenna, Dual-band antenna, Netwok analyze, Micosti line feed INTRODUCTION In ecent yea te use of micosti antenna as become quit oula because of tei oeties suc as low ofile, ligt weigt, comact and confomable is stuctue and easy to fabicate[]. Te aetue couled micosti antenna fist oosed by Poza [] in 985 as a numbe of advantages ove ote feeding metod involving galvanic contact between te antenna and feed line. Te aetue is usually centeed wit esect to te atc wee te atc as its maximum magnetic field. A simle tecnique fo canging te esonant fequencies wit out esulting to a new antenna [3-4]. Te idea is intoduce an ai ga vaiation between te single atc and aetue couled micosti antenna. Te ai ga vaiations affect te esonant fequencies. Te esonant fequencies can teefoe be tuned by te vaiation of ai ga. Te band widt will also inceases aticulaly due to te inceases in te eigt of te dielectic medium. A numbe of exeiment and teoetical stuctue ave been caied out to analyze and design aetue couled micosti antenna. Full wave analysis using te metod of moments as been used to detemine te vaious antenna aametes [5-8]. A tansmission line [9] and cavity model [0] ave been oosed as iciently analysis and design metod. Recently an ect of te diffeent saes aetue couled micosti slot antenna [] and ciculaly olaized aetue couled micosti antenna wit esonant slot and a sceen was oosed []. Otimum design of an aetue couled micosti atc antenna descibe in details [3]. An Intoduction of aetue couled micosti slot antenna wit micosti line feed as been discussed [4]. In tis ae a simle but accuate design metod fom ai ga aetue micosti antenna is esented. Te dual-band oeation of ai ga aetue couled micosti antenna ae useful in many alication suc as dualband tansmit eceive models fo sace veicles. II ANTENNA DESIGN Te oosed ai ga aetue couled micosti antenna is sown in Fig. (a). In tis figue tee ae two antennas.. Ue atc (single atc). Aetue couled atc wit micosti line Te single atc is design by using 3.0GHz and te aetue couled atc is design at.5ghz. Te side view of te ai ga aetue couled micosti antenna is sown in Fig. (b). Te adiating micosti atc element is inted on te to of te substate and te micosti feed lone is inted on te bottom of te feed substate. Te fist ting to design of te atc is coosing a suitable substate of suitable tickness. Taking low dielectic substate to inceases te band widt and adiation iciency of te antenna. A micosti antenna in its simlest fom consists of a adiating atc on one side of dielectic substate and a gound lane on te

2 ote side. Tansmission line model is used fo analyzing te atc antenna fo ectangula saes. A simle atc antenna can be designed fo te given dielectic constant.. Lengt and widt of single atc: To design te ectangula atc widt of te antenna is given by c u () f wee C velocity of ligt widt of te micosti atc Dielectic constant of te substate f L f u L s s L L u (5) Lengt of te esonant element is given by c L l () f wee Effective dielectic constant of te substate l Line extension and l can be exessed as 0 u (3) 0. 5 gound lane micosti line Fig. (a) To view of Aetue coule micosti antenna ue atc aetue ai ga u 0.6 l 0.4 u (4) wee, is te tickness of te substate. Finally te actual lengt of te single atc antenna is obtained as L L l.te single atces u wee designed to oeate at a esonant fequency of 3.0 GH z, tei lengt and widt wee calculated to be L u 3.0mm and widt u 30.0mm esectively.. Lengt and widt of aetue couled atc: Te dimension of aetue couled micosti antenna can also calculated by using above tansmission equations. Te dimension of Z π 4 4 In. A π Fig. (b) Side view of Aetue coule micosti antenna aetue couled micosti antenna emaining was deigned at a esonant fequency of.5 GH z, tei lengt and widt wee calculated to be L 7.78 mm and widt 36.8 mm esectively..3 Slot widt: Te widt of slot affect couling level fom te feed lines to te atc. Geneally te ation of te slot lengt to te slot widt is ket tyically as 0:. In tis ae te widt of te slot is taken s.0 mm..4 Slot lengt: Te couling level is imaily decided by te slot lengt. Tee ae two tyes of te slot ae used in aetue couled micosti antenna design tey ae esonate and non esonate tye based on te lengt of lengt slot. If te slot lengt is comaable to te alf of te wave lengt of te antenna it is called as te esonant slot. If small lengt slot ae used it is non esonant.5 Feed line widt: Te ysical size of te antenna deived fom micosti tansmission line, te micosti antenna is modeled as a lengt of tansmission line of caacteistics [5-6] imedance given by (5) (6)

3 8 4 4 A. π ee and (6) t In π t If we elace wit 4e w t (7) π Z 0 In Ωif (9) 4 Otewise 0π Z 0 Ω In.449 (0) is exessed as follow 0.04 if () (8) Caacteistics imedance evaluation of micosti is imotant to detemine te widt of te feeding line calculated using equation (6). Te widt of a Z 0 50 Ω lime w3.0 mm.5 Feed line osition wit esect slot: Fo maximum couling te feed line must be laced ositioned to te cente of slot. Skewing te feed line fom te slot will educe te couling as will ositioning te feed line towad te edge of slot..6 Position of te atc wit esect to slot: Fo te maximum couling te atc sould be centeed ove te slot, moving te slot in H-field diection little ect on te antenna efomance. But if it is moved in E-field leads to eduction in couling.7 Lengt of tuning stub: Te lengt stub is used to tun te excess eactance of te slot could antenna. He stub is tyically sligtly less tan λ g 4 in lengt. III EXPERIMENTAL MEASUREMENTS Te ai ga aetue couled micosti antenna was measued using netwok analyze [Agilent E8363B A.04.06] fo obtaining te desied dual-fequency beavio. Te aim of ai ga vaiation to see te ow te esonant fequencies ae sifting. Te inut imedance is easily matced by te vaiation of ai ga. Te vaiation of ue and lowe esonant fequencies and tei ation wit ai ga vaiation is sown in Table. In ode to study te efomance of designed ai ga aetue couled micosti antenna etun loss and band widt wee measued exeimentally wit ai ga vaiation ae sown in Table. Te band widt is acieved about 35% wit ai ga vaiations. Table-Vaiation of ue and lowe esonant fequencies and tei ation wit ai ga vaiations Ai Ga Vaiation (mm) Lowe esonant fequency (f ) in GHz Ue esonant fequency (f ) in GHz Ratio of esonant fequencies (f /f ) in GHz Otewise

4 Table -Vaiation esonant fequencies, etun loss and band widt wit te vaiations of ai ga Lowe esonance fequency f (GHz) Ue esonance fequency f (GHz) Retun loss(db) fo f (GHz) Retun loss(db) fo f (GHz) IVDESIGN PARAMETERS Fo designing te ai ga aetue couled micosti antenna following aamete was used. Substate mateial used Glass Eoxy Tickness of te dielectic substate.6 mm Relative emittivity of te substate 4.5 Fequency fo single atc antenna f 3.0 GHz Fequency fo ACM antenna f.5 GHz Tickness of te atc t 0.008cm Pemittivity constant x0 - F/m Calculated using te standad equations, wic ae given below. Dimensions of single atc 3.0x 30.5 mm Dimension of ACM antenna7.78x 36.8 mm Dimensions of te slot (L s x s ).0x 0.0 m Lengt of te micosti line L f 4.70 mm idt of te micosti line f 3.0 mm Band widt in % V DISCUSSION OF RESULT. Te vaiation of inut imedance wit fequency fo aetue couled micosti antenna wit ai ga vaiation as sown in Fig. [(a)-(c)]. It is obseved tat wen we ae inceasing te ai ga [0to 6 mm]vaiation between te single atc and aetue couled micosti antenna sows dual esonance in wic lowe esonance fequency inceases wee as ue esonance fequency is almost constant wit inceasing ai ga.. Te vaiation of VSR wit fequency fo aetue couled micosti antenna wit ai ga vaiation as sown in Fig 3. [(a)-(c)]. It is obseved tat te value of VSR coesonding to lowe esonance fequency is inceases fom.4 to. wit inceasing te ai ga [0to 6 mm] vaiation between te single atc and aetue couled micosti. ee as at te ue esonance fequency te value of VSR is also inceased fom.8 to.3 3. Te vaiation of esonance fequencies wit etun loss is sown in Fig 4. [(a)-(c)].it is obseved tat te value of etun loss coesonding lowe esonance fequency deceases fom -4dB to - 8.5dB wit inceases te ai ga. ee as at ue esonance fequency is also deceases fom -0dB to -7.5dB wit inceases te ai ga. 4..Te vaiation of esonance fequency atio f /f wit inceases te ai ga between te single atc and aetue couled micosti antenna ae deceases. It is sown in Fig.5 VI CONCLUSIONS Tis ae as investigated ai ga between single atc antenna and aetue couled micosti antenna. By using ai ga vaiation between single atc antenna and aetue couled micosti antenna is obtain dual-band oeation. It is obseved fom exeimental esults good imedance matcing at bot esonant fequencies. Te oveall band widt is also acieved 35% of te aetue couled micosti antenna. Te atio of esonance fequency atio is found deceasing (. to.6 GHz) wit inceasing te ai ga vaiation. Teefoe te oosed antenna can be used fo dual sim mobile alication ACKNOLEDGMENTS Te autos would like to tank Si R. K. Malaviya of te Sace Alication Cente, Indian Sace Reseac Oganization Amedabad, fo oviding te measuement facilities. REFERENCES []. I. J BaI and Bata P, Micosti Antennas, Massacusetts (USA) Atec House, (980). []. D. M. Poza, Micosti antenna aetuecouled to a micostiline, Electonics Lett (985), [3]. K.F Lee and J.S Daele, Mode caacteistics of annula-ing and cicula-disc micosti antenna wit and witout ai gas, IEEE Tans. Antenna Poagat Soc. Int Sym Diges, (983), [4]. C. S Lee and V Nalbandian, Imedance matcing of dual-fequency micosti antenna wit an ai ga, IEEE Tans. Antenna Poagat 4 (993), [5]. P. L Sullivan and Scaubet, Analysis of an aetue-couled micosti antenna, IEEE Tans. Antenna Poagate 34 (986), [6]. D. M. Poza, Reciocity metod of analysis fo inted slot and slot-couled micosti antenna, IEEE Tans. Antenna Poagat 34 (986), [7]. A. K Battacayya, Y.M.M Anta and Ittiiboon A, Full wave analysis of an aetuecouled atc antenna, Electon Lettes (UK) 7(99), 555. [8]. C u, K.L u, Z. Q Bi and J Litva, Accuate caacteization of lana inted antenna using finite -diffeence time-domain metod, IEEE Tans. Antenna Poagate 40 (99), Fi wi an

5 [9]. M Himdi, J.P Daniel and C Teet, Tansmission line analysis of aetue-couled micosti antenna, Electon Lett 5 (989), [0]. A Ittiiboon, R Oostlande, Y.M.M Anta and M Cucaci, A model exansion metod of analysis and measuement on aetue-couled micosti antenna, IEEE Tans. Antenna Poagate 39,(99), []. Z Aijaz and S.C Sivastva, Effect of te diffeent saes aetue couled micosti slot antenna, Int. Jounal of Electonics Engineeing (00), []. S. G Kiov and P.D Miaylova, Ciculaly olaized aetue couled micosti antenna wit esonant slot and a sceen was, Radioengineeing 9, (00), -6. [3]. P. J Kim, Otimum design of an aetue couled micosti atc antenna, Mico Ot Tec Lett 39 (003), [4]. S. C Sivastava and Z Aijaz, An Intoduction of aetue couled micosti slot antenna, Int Jounal of Engineeing Tec ( 00), [5]. Q Song and Xia X Zang, A study on wideband ga-couled micosti antenna aays, IEEE Tans. Antenna Poagate 43 (995), [6]. M Ali, A Kacoui and M Samet, Novel metod fo lana micosti antenna matcing imedance, Jounal of Telecommunications, (00), Fig. (b) Te vaiation of inut imedance wit fequency fo aetue couled micosti antenna wit ai ga vaiation 4.0mm Fig. (c) Te vaiation of inut imedance wit fequency fo aetue couled micosti antenna wit ai ga vaiation 6.0mm Fig. (a) Te vaiation of inut imedance wit fequency fo aetue couled micosti antenna wit ai ga vaiation.0mm Fig. 3 (a) Te vaiation of VSR wit fequency fo aetue couled micosti antenna wit ai ga vaiation.0mm

6 Fig. 3 (b) Te vaiation of VSR wit fequency fo aetue couled micosti antenna wit ai ga vaiation 4.0mm Fig. 3 (c) Te vaiation of VSR wit fequency fo aetue couled micosti antenna wit ai ga vaiation 6.0mm Fig. 4 (a) Te vaiation of etun loss wit fequency fo aetue couled micosti antenna wit ai ga vaiation.0mm Fig. 4 (b) Te vaiation of etun loss wit fequency fo aetue couled micosti antenna wit ai ga vaiation 4.0mm RATIO OF RESONANCE FREQUENCIES, GHZ Feq.Ratio VARIATION OF AIR GAP, MM Fig. 4 (c) Te vaiation of etun loss wit fequency fo aetue couled micosti antenna wit ai ga vaiation 6.0mm Fig. 5 Te vaiation esonance fequency atio fo aetue couled micosti antenna wit ai ga