ISSN: 2229-6948(ONLINE) DOI: 10.21917/ijct.2013.0095 ICTACT JOURNAL ON COMMUNICATION TECHNOLOGY, MARCH 2013, VOLUME: 04, ISSUE: 01 BANDWIDTH AND GAIN ENHANCEMENT OF MULTIBAND FRACTAL ANTENNA BASED ON THE SIERPINSKI CARPET GEOMETRY Maas Raja Jea 1, B.B. Magaraj 2 ad Debasis Mishra 3 Departmet of Electroics ad Telecommuicatio Egieerig, Veer Suredra Sai Uiversity of Techology, Idia E-mail: 1 maas.syergy@gmail.com, 2 bbmagarajuce@yahoo.com ad 3 debasisuce@gmail.com Abstract I this paper, we have achieved a compact multibad fractal atea based o Sierpiski carpet geometry. The simulatio of the proposed atea is doe by CST Microwave Studio EM simulatio software. The Sierpiski carpet fractal atea proves that it is capable to create multibad frequecies. There are four resoat frequecies appeared at 0.85 GHz, 1.83 GHz, 2.13 GHz ad 2.68 GHz. Simulated results idicates that the retur loss is better tha 15 db, the is less tha 1.3,the directivity is greater tha 6dBi & the gai is more tha 6dB i each bad. So this fractal atea ca be suitable for fixed microwave & aviatio applicatios. Keywords: Fractal Atea, Sierpiski Carpet, CST, IFS, Multibad 1. INTRODUCTION Ateas are regarded as the largest compoets of itegrated, coformal & low-profile wireless commuicatio systems. Therefore, it is desired for the atea miiaturizatio i achievig a optimal desig for wireless commuicatios [3]. It is well kow that the dimesio of the atea is a fuctio of its operatig wavelegth (), i.e., if the atea s size is less, it becomes iefficiet because its radiatio resistace, gai, directivity ad badwidth are isolvet. Fractal geometry provides a pleasat solutio for this problem o accout of its two major characteristics: self-similarity ad space fillig. So, fractal theories have become a pioeerig approach for desigig & characterizig widebad ad multibad ateas [3], [1]. A Fractal is a repeated geerated structure havig a fractioal dimesio which provides wide flexibility i atea desig & aalysis. Fractal atea egieerig is the field, which utilizes fractal geometries with IFS for atea desig. Presetly, it has become oe of the buddig fields of atea egieerig due to its advatages over covetioal atea desig. Most of the fractal geometries have the followig characteristic features: ifiite complexity ad detail, fractioal dimesio self-similarity, space fillig & idepedet [1]. These importat characteristic features of fractals ca be utilized i atea desig to achieve the followig advatages: Miiaturizatio: We kow that a atea radiates efficietly oly whe its size is a correspodig fractio of the wavelegth of operatio. Therefore size of the ateas will be very large that operate at very low frequecies. The beefit of fractal atea is that usig fractioal dimesio of the fractals provides ateas that are electrically very log but physically small [2]. Multibad/widebad ateas: We kow that a atea must have o characteristic size or it must have may characteristic sizes to operate over multiple frequecies simultaeously to be idepedet. Due to the self-similarity & space fillig property of fractals there are multiple copies of the geometry i a fractal object ad hece they ca be utilized for multibad/widebad ateas [3], [4]. Better efficiecy: Fractal geometry have sharp corers ad edges that cause rapid chages i the directio of curret ad ca be used to icrease the radiatio parameters. So fractals are efficiet radiators of electromagetic eergy that ca be used desigig ateas with better efficiecy. Now-a-days, the advacemet of wireless commuicatio systems led to the developmet of several wireless commuicatio applicatios icludig compact atea desig. To icorporate more tha oe commuicatio service i a wireless system device, multibad ateas should be used. Multibad atea provides solutio to the space problem comparative to the traditioal way of usig differet ateas for differet bads [7]. 2. ANTENNA DESIGN The Sierpiski carpet is a determiistic fractal that is a geeralizatio of the Cator set preseted over two dimesios. This fractal is build startig with a square i the plae, subdividig it ito ie smaller cogruet squares droppig the ope cetral oe, the subdividig the eight remaiig squares ito ie smaller cogruet squares i each of which the ope cetral oe is dropped [4]. This process is cotiued ifiitely ofte obtaiig a limitig cofiguratio which ca be see as a geeralizatio of the Cator set. The desigs up to three iteratio are proposed i this paper that as show i Fig.1. (a) Iteratio 0 (b) Iteratio 0 (c) Iteratio 2 (d) Iteratio 3 Fig.1. The multiple iteratio stages of the proposed Sierpiski Carpet Fractal atea 669
MANAS RANJAN JENA et. al.: BANDWIDTH AND GAIN ENHANCEMENT OF MULTIBAND FRACTAL ANTENNA BASED ON THE SIERPINSKI CARPET GEOMETRY Let s cosider that N be the umber of black boxes, L is the scale factor for legth of a side of gree boxes, A is the scale factor for fractioal area of black boxes after the th iteratio. N = 8 (1) 1 L (2) 3 A 2 L N 8 9 The proposed multibad atea is preseted i Fig.1. Here we have used Probe Feed techique for the desiged atea. The total legth ad width of groud plae is 70 mm each as it is Square Carpet Atea. The legth ad width of probe feed carpet patch are 63 mm each. We have used FR4 with r = 4.4 as a material for substrate ad PEC as a coductig material for probe. We have started the atea desig process with Sierpiski Carpet Plaar Moopole Atea. I the first iteratio, the first basic square patch is segmeted ito ie cogruet squares by takig scale factor 1 3 ad the middle square is detached from it. For secod iteratio segmets are doe o edurig eight squares ad the detachig their respective middle squares. For further iteratios, the same procedure is used with same scale factor. By usig this method we have desiged three iteratios as show i Fig.1. (3) Fig.2(b). Variatio of with Fig.2(c). 3D Radiatio patter () at = 3.288 GHz 3. RESULTS AND DISCUSSIONS CST Microwave Studio EM simulator software is used for desig ad simulatio. Results like Reflectio coefficiet (retur loss),, 3D radiatio patters are simulated. Simulatio results of multiple iteratios are summarized i Table.1, Table.2, Table.3 ad Table.4. Simulated Results of Iteratio 0 Fig.2(d). 3D Radiatio patter () at = 3.288 GHz Table.1. Simulatio results of Iteratio 0 Gai 1.264-16.19 1.36 6.043 1.550 Simulated Results of Iteratio 1 Fig.2(a). Variatio of simulated reflectio coefficiet (S11) with Fig.3(a). Variatio of simulated reflectio coefficiet (S11) with 670
ISSN: 2229-6948(ONLINE) ICTACT JOURNAL ON COMMUNICATION TECHNOLOGY, MARCH 2013, VOLUME: 04, ISSUE: 01 Fig.3(b). Variatio of with Fig.3(f). 3D Radiatio patter (Gai) at = 3.536 GHz Fig.3(c). 3D Radiatio patter () at = 3.288 GHz Fig.3(g). 3D Radiatio patter () at = 4.56 GHz Fig.3(d). 3D Radiatio patter (Gai) at = 3.288 GHz Fig.3(h). 3D Radiatio patter (Gai) at = 4.56 GHz Table.2. Simulatio results of Iteratio 1 Gai 3.288-15.5 1.336 9.602 9.393 3.536-17 1.3 5.956 5.629 4.56-13 1.4 9.440 9.019 Simulated Results of Iteratio 2 Fig.3(e). 3D Radiatio patter () at = 3.536 GHz Fig.4(a). Variatio of simulated reflectio coefficiet (S11) with 671
MANAS RANJAN JENA et. al.: BANDWIDTH AND GAIN ENHANCEMENT OF MULTIBAND FRACTAL ANTENNA BASED ON THE SIERPINSKI CARPET GEOMETRY Fig.4(b). Variatio of with Fig.4(f). 3D Radiatio patter (Gai) at = 4.71 GHz Table.3. Simulatio results of Iteratio 2 Gai 4.54-19.43 1.22 9.262 7.524 4.71-11.6 1.72 3.961 0.5709 Simulated Results of Iteratio 3 Fig.4(c). 3D Radiatio patter () at = 4.54 GHz Fig.5(a). Variatio of simulated reflectio coefficiet (S11) with Fig.4(d). 3D Radiatio patter (Gai) at = 4.54 GHz Fig.5(b). Variatio of with Fig.4(e). 3D Radiatio patter () at = 4.71 GHz Fig.5(c). 3D Radiatio patter () at = 4.544 GHz 672
ISSN: 2229-6948(ONLINE) ICTACT JOURNAL ON COMMUNICATION TECHNOLOGY, MARCH 2013, VOLUME: 04, ISSUE: 01 Fig.5(d). 3D Radiatio patter (Gai) at = 4.544 GHz Fig.5(e). 3D Radiatio patter () at = 4.706 GHz Fig.5(f). 3D Radiatio patter (Gai) at = 4.706 GHz Table.4. Simulatio results of Iteratio 3 Gai 4.544-38.53 1.036 9.359 7.417 4.706-17.47 1.21 4.491 1.252 With the above simulated results aalysis of ad Retur Loss measuremets, the desigs shows multibad characteristics at various operatig frequecies with multiple iteratios. For the First iteratio we get of 1.336 at 6.48GHz as show i Fig.3(a) ad Fig.3(b). To miimize the towards ideal coditio we go for secod ad third iteratio. For secod iteratio the three bads obtaied are 4.44 4.55 GHz, 8.15 8.4 GHz ad 10.8 11.24 GHz as observed from Fig.4(a) ad Fig.4(b), ad for third iteratio as 4.32 4.44 GHz, 8.12 8.4 GHz ad 10.8 11.20 GHz, ca be observed from Fig.5(a) ad Fig.5(b). Comparig plots for desigs of all iteratios oly secod ad third iteratio desigs achieve desired results at frequecies of 4.4 GHz ad 8.2 GHZ ad 11GHz ad acts as multibad ateas. BW Calculatio a) For 0 th iteratio f c = 1.264 GHz, f L = 1.196 GHz & f H = 1.356 GHz =1% fc b) For 1 st iteratio For 1 st bad f c = 3.288 GHz, f L = 3.224 GHz & f H = 3.338 GHz = 3.46% fc For 2 d bad f c = 3.536 GHz, f L = 3.507 GHz & f H = 3.567 GHz = 1.69% fc For 3 rd bad f c = 4.56 GHz, f L = 4.523 GHz & f H = 4.589 GHz = 1.44% fc c) For 2 d iteratio For 1 st bad f c = 4.54 GHz, f L = 4.504 GHz & f H = 4.593 GHz = 1.96% fc For 2 d bad f c = 4.71 GHz, f L = 4.67 GHz & f H = 4.74 GHz = 1.48% fc d) For 3 rd iteratio For 1 st bad f c = 4.544 GHz, f L = 4.502 GHz & f H = 4.596 GHz = 2.09% fc For 2 d bad f c = 4.706 GHz, f L = 4.64 GHz & f H = 4.76 GHz = 2.54% fc Table.5. Compariso of differet major parameters for multiple iteratios Parameters 0 th iteratio Retur loss -16.19 1.356 1 st iteratio -15.5-17.12-13.14 1.336 1.3 2 d iteratio -19.43-11.6 1.22 1.72 3 rd iteratio -38.53-17.47 1.036 1.21 673
MANAS RANJAN JENA et. al.: BANDWIDTH AND GAIN ENHANCEMENT OF MULTIBAND FRACTAL ANTENNA BASED ON THE SIERPINSKI CARPET GEOMETRY 6.043 Gai 1.550 Presece of multibad BW ehacemet 1.4 9.602 5.956 9.440 9.393 5.629 9.019 9.262 3.961 7.524 0.570 9.359 4.491 7.417 1.252 Nil Yes(3) Yes(2) Yes(2) 0.1% 3.46% 1.69% 1.44% 1.96% 1.48% 2.09% 2.54% Size reductio 33.3% 44.4% 52.1% 4. CONCLUSION A multibad fractal atea based o Sierpiski carpet geometry is desiged & simulated. The proposed Fractal atea results are compared with a simple rectagular patch of 63mm 63mm dimesio. The simulated results show that retur loss is more tha -15 db, is less tha 1.3, directivity is more tha 6 dbi, ad gai is more tha 6 db. Multibad property is achieved with multiple iteratios. Gai is ehaced with multiple iteratios. Badwidth ehacemets for multiple iteratios are compared. Atea size is reduced by usig fractal shapes with multiple iteratios. So the desiged atea ca be proposed for the fixed microwave & aviatio applicatios. ACKNOWLEDGEMENT The authors sicerely thak to the Vice Chacellor & the Head of the Departmet of Electroics ad Telecommuicatio Egieerig, Veer Suredra Sai Uiversity of Techology, Burla for costat ecouragemet ad support. REFERENCES [1] Balais ad Costatie, Atea theory-aalysis ad Desig, Joh Wiley & Sos Ltd, Reprited 2008. [2] B. B. Madelbrot, The Fractal Geometry of Nature Sa Fracisco, CA: Freema, 1983. [3] Philip Felber, Fractal Ateas-A Literature Study, Illiois Istitute of Techology, 2000. [4] R. M. Crowover, Itroductio to Fractals & Chaos, Bosto, MA: Joes & Bartlett, 1995. [5] Noorsaliza Bt Abdullah Microstrip Sierpiski Carpet Atea Desig, M.E. diss., Departmet of Electroics & Telecommuicatios, Uiversiti Tekologi Malaysia, 2005. [6] J. P. Giavittorio ad Y. Rahmat-Samii, Fractal Atea:A ovel atea miiaturizatio techique ad applicatio, IEEE Atea ad Propagatio Magazie, Vol. 44, No. 1, pp. 20-36, 2002. [7] Best S. R, O the Sigificace of Self-Similar Fractal Geometry i Determiig the Multibad Behaviour of Sierpiski Gasket Atea, IEEE Ateas ad Wireless Propagatio Letters, Vol. 1, No. 1, pp. 22-25, 2002. [8] D. H. Werer, P. L. Werer, ad K. H. Church, Geetically egieered multi-bad fractal ateas, Electroics Letters, Vol. 37, No. 19, pp. 1150 1151, 2001. [9] D. H. Werer ad S. Gaguly, A overview of fractal atea egieerig research, IEEE Ateas ad Propagatio Magazie, Vol. 45, No. 1, pp. 38-57, 2003. [10] N. Cohe, Fractal Atea Applicatio i Wireless Telecommuicatios, Professioal Program Proceedigs of Electroics Idustries Forum of New Eglad, pp. 43-49, 1997. 674