A Simple Modified Transmission Line Model for Inset Fed Antenna Design

Transcription

1 IJCSI Interntionl Journl of Computer Siene Issues, Vol. 7, Issue 5, Septemer ISSN (Online): A Simple Modified Trnsmission ine Model for Inset Fed Antenn Desin M. Fwzi Bendhmne, Mehdji Ari, F. Trik Bendimerd 3 nd Noureddine Boukli-Hene 4 Teleommunitions ortory, Tehnoloies Fulty, Aou-Bekr Belkïd University Tlemen, 3, Aleri Teleommunitions ortory, Tehnoloies Fulty, Aou-Bekr Belkïd University Tlemen, 3, Aleri 3 Teleommunitions ortory, Tehnoloies Fulty, Aou-Bekr Belkïd University Tlemen, 3, Aleri 4 Teleommunitions ortory, Tehnoloies Fulty, Aou-Bekr Belkïd University Tlemen, 3, Aleri Astrt In this pper we propose the desin of sinle inset fed printed ntenn sed on simple modified trnsmission line model. The developed model is simple, urte nd tkes into ount ll ntenn hrteristis nd their feed system. To test the proposed model, the otined results re ompred to those otined y the moment s method (Ailent softwre). Usin this trnsmission line pproh the resonnt frequeny, input impedne, return loss n e determined simultneously. The pper reports severl simultion results tht onfirm the vlidity of the developed model. The otined results re then presented nd disussed. Keywords: Printed inset fed ntenn, trnsmission line model, moment s method ().. Introdution Mirostrip ntenns reeived onsiderle ttention in the 97 s, lthouh the first desins nd theoretil models ppered in the 95 s. They re suitle for mny moile pplitions: hndheld devies, irrft, stellite, missile, et. They hve een extensively investited in the literture [-5]. Conventionl mirostrip ntenns in enerl hve ondutin pth printed on rounded mirowve sustrte, nd hve the ttrtive fetures of low profile, liht weiht, esy frition, nd onformility to mountin hosts []. Trditionl feedin tehniques inlude the use of diretly, eletromnetilly, or perture oupled mirostrip lines, oxil proes, nd oplnr wveuides. Mny types of mirostrip ntenns hve een proposed nd investited [-5]. Mirostrip ntenns tht operte s sinle element usully hve reltively lre hlf power em width, low in nd low rdition effiieny. Mny reserhers studied their si hrteristis nd ret efforts were lso devoted to their determintion (resonnt frequeny, the nd-width, rdition... et) y usin theoretil models. Over the yers, mny models hve een used to nlyze mirostrip ntenns. Amon them, the trnsmission line model is simple model due to its ssumptions. This leds to set of liner equtions with low dimension. In this pper we look into the desin nd development of sinle ntenn nd inset fed ntenns rrys with orporte feed network y usin fst, simple nd urte modified trnsmission line model. The most importnt prmeter in our desinin proess is the simpliity of the ntenn nd its feedin struture so tht the ntenn n e frited esily in prtie. Therefore, inset fed pth ntenn with mirostrip line feed ws onsidered s se struture.

2 IJCSI Interntionl Journl of Computer Siene Issues, Vol. 7, Issue 5, Septemer ISSN (Online): Trnsmission ine Model Anlysis In this setion, n equivlent iruit model for the proposed ntenn is developed. This model is ple of preditin the slot rdition ondutne nd the ntenn input impedne ner resonne. This pproh provides very helpful insiht s to how this ntenn nd its feed network operte. As mentioned efore, this model is lso needed to find proper mthin network for the ntenn. 3. Three Ports Model of the Proposed Inset Fed Antenn The used model is inspired from the three ports model [8]. On the fiure elow one presents the suested onfiurtion: Pro feed W f Input 5 Ω Rin Rin m l l W S W (,W ) ( m,w f) (,W ) (,W ) (,W ) () () (, W ) (,W ) Fi. () Inset fed ntenn. () Equivlent iruit of the proposed ntenn. l W Rin In the present study, the model onsists of rekin up the ntenn into three res, nd. et us onsider eh prt s ein n ntenn whih finishes on the level of its ends y lenth due to the slot rdition nd resistne in series representin the vlue of this resistne in the ntenn extremity. The improved model onsist of neletin the rditions slots etween the feed line nd the res nd nd reple the resistnes in series y their true vlues due only to the res nd. Therefore resistnes will e R in nd R in insted of only one resistne R in. The vrious vlues of the model re iven s follows: The input resistne is iven y: R R in in G G G G os B sin os B sin G B () sin sin G B () G B os sin R in G G B sin (3) The expressions of G nd B re iven y the reltions elow [9]: W,, G,, kh 4 (4) W,, B,,. 636ln kh (5) The ondutne of sinle slot n lso e otined y usin the expression field derivtive from model vity. In enerl, the ondutne is defined y: Prd G V (6) By usin the eletri field one n lulte the rdited power: KW sin os V P 3 rd sin d os (7) The self ondutne n e lulted usin the followin expressions: I G (8) Where I is the interl defined y: kw sin os 3 I sin d os The slots lenth for eh reion is iven y: (9)

3 IJCSI Interntionl Journl of Computer Siene Issues, Vol. 7, Issue 5, Septemer ISSN (Online): f r reff () f r reff f r reff The resonnt frequeny in this se for eh reion is iven y: v f r r r v f r () r r v f r r r mirostrip, the onnetion to point inside the metl pth requires the use of n inset. The inset-feed tehnique intertes pth ntenn toether with mirostrip feed on sinle plnr sustrte. The input impedne of the inset-fed pth vries, similrly to the oxil proe-fed pth, s the inset-depth of the feed line hnes. The simulted input return loss of the inset fed ntenn is displyed for frequenies etween 3.5 to 5.5 GHz in Fi.3. S [db] Frequeny [GHz] 4. Results nd Disussions The vlidity of the model suested is hihlihted y omprin the results of the return loss, the input phse nd input impedne lous. In this setion simultions were performed on inset fed ntenn. 4. Inset Fed Antenns Arry Opertin t the Resonnt Frequeny 5.4 GHz The ntenn is to e desined on sustrte whih hs reltive permittivity r of.4, dieletri thikness H of.7 mm, loss tnent of out, nd.5 mm ondutor thikness. Fi. 3 Simulted input ntenn return loss. At the frequeny 4.7 GHz one oserve pperne of resonnt mode nd ood dpttion. It ppers pek of -6.3 db usin the moment method nd of -3 db usin the improved trnsmission line model. VSWR Frequeny [GHz] 5 Fi. The msk lyout of the inset fed pth ntenn desin opertin t 4.7GHz. The prmeters re set to: W =3.4 mm, =9.3 mm, H=.7 mm, S=.57 mm, W f =.4 mm, =4.9 mm. Fi. 4 Simulted input ntenn VSWR. The Moments results nd those otined from trnsmission line model of the input phse of return loss for this ntenns rry re shown in Fi. 5. Usin the trnsmission line model, the ntenn ws desined to operte with resonnt frequeny of 4.7 GHz. The input impedne of the ntenn must e mthed to the feed line y hoosin the orret position for the feedin point. Beuse the ntenn must e fed with the

4 IJCSI Interntionl Journl of Computer Siene Issues, Vol. 7, Issue 5, Septemer ISSN (Online): The simulted input return loss of the ntenns rry is displyed for frequenies etween 4. to 7. GHz in Fi.8. Phse [ ] S [db] Frequeny [GHz] - Fi. 5 Refleted phse t the ntenn input. One noties very well tht the phse is null y the two models in spite of the shift oserved. The impedne lous of the ntenns rry from 3.3 to 5.4 GHz is illustrted on Smith's hrt in Fi Frequeny [GHz] Fi. 8 Computed return loss of the inset fed ntenn. 4 VSWR Frequeny [GHz] Fi. 6 Smith's hrt of the input impedne return losses. Frequeny points iven y strt = 3.3 GHz, stop = 5.4 GHz. 4. Inset Fed Antenns Arry Opertin t the Resonnt Frequeny 5.4 GHz In this setion, other eometry is nlyzed y usin the method proposed in this pper. The ntenn is to e desined on sustrte whih hs reltive permittivity r of 4.6, dieletri thikness H of.444 mm, loss tnent of out,5 nd.5 mm ondutor thikness. The ntenn ws desined to operte with resonnt frequeny of 5.4 GHz. The inset fed ntenn rhiteture is shown in the fiure elow. Fi. 9 Computed VSWR. We note from Fi. 9 tht the two urves re identil. In the viinity of the resonnt frequeny the VSWR is lose to unity. In Fi. we present the refleted phse t the ntenn input. Phse [ ] Frequeny [GHz] 5 Fi. Refleted phse t the ntenn input. The impedne lous of the ntenns rry from 4. to 7.GHz is illustrted on Smith's hrt in Fi.. Fi. 7 The msk lyout of the inset fed pth ntenn desin opertin t 5.4 GHz. The prmeters re set to: W =6.8 mm, =.7 mm, S=.4mm, W f =.4 mm, =4 mm.

5 IJCSI Interntionl Journl of Computer Siene Issues, Vol. 7, Issue 5, Septemer ISSN (Online): Antenns Arry", Mirowve journl, vol. 49, no. 5, My 6, pp [7] S. n, E. Adel, S. in, A. E. Fthy, A. Kmel, nd H. Elhennwy, "A hihly effiient Vivldi ntenn rry desin on thik sustrte nd fed y SIW struture with interted GCPW feed", 7 IEEE Antenns nd Proption Soiety Interntionl Symposium, 7, pp [8] J. F. Zurher & F. E. Grdiol, Brodnd Pth Antenn, Boston : Arteh House. [9] C.A. Blnis. Antenn Theory Anlysis nd Desin, Seond Edition, USA: John Wiley & Sons, 997. [] K.. Won, Desin of Nonplnr Mirostrip Antenns nd Trnsmission ines, New ork: Wiley, 999. Fi. Smith's hrt of the input impedne return losses. Frequeny points iven y strt = 4. GHz, stop = 7. GHz. 5. Conlusion In this pper, hihly-flexile nd omputtion-effiient trnsmission line model is developed to nlyze the inset fed ntenn. The results so fr show tht the trnsmission line model n e suessfully used to desin the inset fed ntenns rry nd even thouh the model is oneptully simple, it still produes urte results in reltively short period of omputin time. The results otined hihlihted n exellent reement etween the trnsmission line model nd the moment s method. A omprison of the results produed y the finl model with the moment s method dt showed the vlidity of the proposed model. This llows the nlysis of very lre rrys even on rther smll omputer. Bsed on these hrteristis, the proposed ntenns rry n e useful for EMC pplitions. Referenes [] R. A. Sinti, CAD of Mirostrip Antenn for Wireless Applitions, Arteh House: I., 996. [] S. Go nd A. Smell, "A Simple Brodnd Printed Antenn", proress in eletromnetis reserh, PIER 6, 6, pp [3] P. M. Mendes, M. Brtek, J. N. Burhrtz nd J. H. Correi, "Desin nd Anlysis of 6 GHz Chip Antenn on Glss Sustrtes for Intertion with RF/Wireless Mirosystems", IEEE proeedin, 3. [4] Wi. Sn-Hyuk, "Widend mirostrip pth ntenn with U- shped prsiti", IEEE Trns Antenns Prop., 55(4):96-9, 7. [5] D. M. Pozr nd D.H. Shuert, Mirostrip Antenns, the Anlysis nd Desin of Mirostrip Antenns nd Arrys, New ork : IEEE Press, 995. [6] M. Ari, Boukli-hene. N, Bendimerd. F. T. & Cmiio. E, "Desin of Dul Bnd Rin Printed M. Fwzi Bendhmne ws orn in Aleri in 976. He otined his mister deree from the Aou Bekr Belkid University, (Tlemen) Aleri, in. M. Fwzi Bendhmne is interested to the followin topis: study of the hrteristis of mirostrip ntenns, theories of lorithmi nd prormmin, optimiztion lorithms, study of the nonliner systems. M. Fwzi Bendhmne urrently is mster ssistnt t the University of Tlemen nd dotorte student in the sme university under the supervision of Pr. F. Trik Bendimerd workin on the study of the ouplin etween mirostrip ntenns. Mehdji Ari ws orn in 978 in Sidi Bel Aès, Aleri. He reeived the Mister nd dotorte diploms in 4 nd 8 from Aou Bekr Belkïd University, Tlemen, Aleri. He is Reserher within the Teleommunitions ortory. His min field of reserh is entered on the nlysis, synthesis of multind ntenn nd ntenns rrys desin. F. Trik Bendimerd ws orn in 959 in Sidi Bel Aès, Aleri. He reeived the Stte Enineer diplom in 983 from Orn Sienes nd Tehnoloies University, Aleri nd the Dotorte Deree from Nie Sophi Antiplois University, Frne, in 989. He is professor nd the Diretor of the Teleommunitions ortory. His min re of reserh is the mirowve tehniques nd rdition nd he is responsile of the ntenn setion. Noureddine Boukli-Hene ws orn in 959 in Tlemen, Aleri. He reeived the Diplome d Etudes Approfondies in mirowve enineerin (DEA Communitions Optiques et Miroondes) nd the Dotorte deree (prepred t the Centre Ntionl d Etudes Sptiles, Toulouse, Frne) in eletril enineerin from imoes University, Frne, in 98 nd 985 respetively. Reently, he is eturer t the University of Tlemen. His reserh interests inlude, mon others, mirostrip ntenns nd mirowve iruits.