Low Profile MIMO Diversity Antenna with Multiple Feed

Transcription

1 2011, TextRoad Publication ISSN X Jounal of Basic and Applied Scientific Reseach Low Pofile MIMO Divesity Antenna with Multiple Feed Waqas Ahmad, Muhammad Wasif Nisa, Ehsan Ullan Muni, Waqas Anwa COMSATS Institute of Infomation Technology, Wah Cantt , Pakistan. COMSATS Institute of Infomation Technology, Abbottabad,Pakistan ABSTRACT A Compact low pofile MIMO Divesity antenna system with multiple feeds with a size of 105mm*61.5mm is poposed. Multiple feeds ae used to povide maximum powe to antenna elements so that signal can popagate a long distance. The poposed antenna is achieving multiple fequencies, i.e. 2.5 GHz, 3.21 GHz, 4.22GHz, 4.68GHz, 6.5GHz, 6.74 GHz, 7 GHz and 8.35 GHz. Measued S-paametes show the isolation is db. The maximum achievable bandwidth is 1.32 GHz (1320 MHz). This antenna can be applicable at Wimax, WLAN, LTE and Satellite Bands. KEY WORDS: Multiple-input multiple-output (MIMO), multi feed, cicula-slots, divesity. 1. INTRODUCTION MULTIPLE-INPUT MULTIPLE-OUTPUT (MIMO) wieless communication systems uses multiple antenna elements at both the tansmit and eceive sides to impove capacity gain as compaed to the usual single-input single-output (SISO) systems [1]. In [2] they have designed a multiband MIMO antenna using a band stop matching cicuit. This antenna is applicable at next geneation mobile applications. At LTE band antenna has the isolation of appoximately 15 db and 20 db at the uppe bands. In [3] a compact Micostip patch antenna opeating at ti-bands is being poposed. The poposed antenna opeates at 2.7 GHz, 3.2 GHz and 5.3 GHz. The antenna has two U-shaped slots and a small gound plane in ode to have bette pefomance. The achieved etun losses ae db, db and - 19 espectively. In [4] they have pesented a single laye, feed, multi fequency, compact ectangula micostip patch antenna. In ode to educe esonant fequencies they have used the mechanism of cutting ectangula slots at the edges with adding two small cicles inside the patch in ode to impove the etun loss. By cutting the edges the antenna size has been educed to 64%. In [5] they have pesented the design of LMDS antenna. They have used apetue coupled method in ode to enlage the band of patch. They have also tied to minimize the finging ect acoss the band patch. Due to which both the antenna iciency and fequency bandwidth ae inceased. In [6] they have pesented a dual-polaized shoted bowtie antenna included with a coss dipole. The dipole is used to get same adiation pattens in ode to balance high back adiations which ae poduced due to shoted patches. The poposed antenna is designed to opeate on DCS, PCS, and 3G mobile communication systems woking between 1.71 and 2.17 GHz. In [7] a wideband plana divesity antenna fo mobile teminal is pesented. The antenna is opeate able on UMTS and WLAN bands and has coesponding bandwidth of GHz including UMTS ( GHz) and 2.4 GHz WLAN ( GHz) bands. The mutual coupling ect of the antenna has also been educed. In [8] a new appoach using diective antenna fo designing MIMO aays is pesented. The main emphasize in this wok is on educing the mutual coupling. In this wok a MIMO aay of pinted Yagi antennas with integated balun is pesented. The end-fie adiation mechanism of the Yagi is exploited to obtain a tiangula aay of thee sectoal antennas. In [9] Metamateial concepts ae used to design a novel ectangula patch antenna. The pattened metal patch and finite gound plane fom a coupled capacitive-inductive (C-L) cicuit of negative index metamateial. In ode to achieve low VSWR, high iciency, low loss and wideband a new type of antenna is used to design Meta aay. The esultant aay has moe bandwidth than oiginal patch aays, and high gain can also be obtained in a wide fequency band. *Coesponding Autho: Muhammad Wasif Nisa, COMSATS Institute of Infomation Technology, Wah Cantt , Pakistan. wasifnisa@comsats.edu.pk 1084

2 Ahmad et al., 2011 In [10] a ectangula patch antenna aay fo MIMO communications was simulated on a magnetic pemeability enhanced metamateial. The antenna pefomance was compaed with conventional aay constucted on nomal substate. The analysis was taken on the basis of degee of mutual coupling fo diffeent element spacing, achievable channel capacity, bandwidth and iciency. The esults show the aay built on the metamateial substate has significant size eduction, less mutual coupling and significant channel capacity impovement compaed to simila aays on conventional substates. 2. Antenna Design In this pape multi-feed Mimo antenna is poposed. The geomety of Mimo antenna is illustated in Figue2. The poposed antenna contains 2 antenna elements having appoximately λ/8 (7.5mm). Each antenna element is feeded with 2 feeds one fom top the othe fom the bottom. Both the antenna elements ae on common gound. The dimension of the antenna elements ae 43mm*27.6mm, dimension of substate and gound ae 105mm*61.5mm. The thickness of the substate is 1.6mm and have dielectic constant of =4.4. The antenna elements ae feeded with tansmission line of 3mm*17mm and have impedance of 50 ohms. Cicula slots have been intoduced to achieve multibands. A cicle with cossing ectangles has been intoduced in middle of each antenna element. The adius of the cental cicle is 6mm and ectangles ae of dimensions 3mm*14mm and 14mm*3mm. fou moe cicles with adius 3mm ae intoduced on the cones of each antenna element. Figue 1: Stuctue of MIMO Antenna Stuctue of antenna in figue 1 has dimension of antenna elements ae 41mm*27.6mm. The spacing between the two antenna elements in this design is λ/6. The antenna Opeates at multiband and the esults ae shown in figue 3. Figue 2: Popsed Stuctue of MIMO Antenna The width and antenna elements spacing of Antenna in Figue 1 have been changed to get the impoved esults. The width of each antenna element is inceased 2mm fom the left-side and the spacing between antenna elements is appoximately λ/8 (7.5mm). As shown in Figue 2. The esults of the poposed stuctue of Mimo antenna is shown in Figue 4. The Antenna s elements width and length ae calculated by the following fomula taken fom [5]. c 2 w 2 f 1 0 (1) 1085

3 In the fomula (l), W is the element s width, C is the velocity of light in fee space, is the elative dielectic constant, and f 0 is the opeational fequency. The ective dielectic constant of the feeding line is calculated by the fomula (2) h w (2) 2 2 Hee, h is the height of the dielectic, and w is the width of the conducto. Because the finging field ect occus aound the patch's edges, the quotient of L is needed to compensate fo fomula (3) ( 0.3)( w / h 0.264) L h(0.412) ( 0.258)( w / h 0.8) The antenna element s length and the ective length ae calculated by the fomula (4) and (5) L 2 L (4) 2 L L 2 L (5) e 3. SIMULATIONS AND RESULTS The simulated esults of fist stuctue pesented in Figue 1 ae shown in Figue 3 below. (3) Figue 3: Simulated esults of Stuctue of MIMO Antenna The simulated esults of enhanced stuctue pesented in figue 2 ae shown in figue 4 below Figue 4: Simulated esults of poposed Stuctue of MIMO Antenna The following tables show the detailed fequencies, etun loss and bandwidth of both the antennas. 1086

4 Ahmad et al., 2011 Table 1: Simulated esults of Stuctue of MIMO Antenna Feq (GHz) Bandwidth (MHz) Retun Loss (db) Table 1 shows the details about the achieved fequencies, bandwidth and etun loss of the Figue 1 of the MIMO Antenna. Following figue epesents the adiation patten of the individual fequencies. (a):2.5 GHz (b):3.21 GHz (c):4.22 GHz (d):4.68 GHz (e):6.49 GHz (f):6.74 GHz (g):7.06 GHz (h):8.35 GHz Figue 5: Radiation patten. 1087

5 In Figue 5 the adiation patten shows the Theta and Phi Patten with values of 0, 90 degees. Radiation patten most commonly efes to the diectional (angula) dependence of the stength of the adio waves fom the antenna. The adiation pattens ae plotted with espect to E-field and H-field: H-field: Theta=all values Phi= 0 90 (0= XZ-Plane, 90=YZ-Plane) E-field :(XY-Plane) Theta=90 Phi= All values Table 2: Simulated esults of poposed Stuctue of MIMO Antenna Feq (GHz) Bandwidth (MHz) Retun Loss (db) Table 2 shows the details about the achieved fequencies, bandwidth and etun loss of the Figue 2 of the MIMO Antenna which is much bette than the esults of Figue 1, hee got moe bandwidth and achieved moe fequencies. 4. Conclusion A Compact low pofile MIMO divesity antenna system with multiple feeds with a size of 105mm*61.5mm is poposed in this pape. Multiple feeds ae used to povide maximum powe to antenna elements so that signal can popagate a long distance. The poposed antenna is achieving multiple fequencies, i.e. 2.5 GHz, 3.21 GHz, 4.22GHz, 4.68GHz, 6.5GHz, 6.74 GHz, 7 GHz and 8.35 GHz. Measued S-paametes show the isolation is db. The maximum achievable bandwidth is 1.32 GHz (1320 MHz). This antenna can be applicable at Wimax, WLAN, LTE and Satellite Bands. REFERENCES [1]. G. J. Foschini and M. J. Gans, On limits of wieless communications In a fading envionment when using multiple antennas, Wieless Pesonal Commun.no. 6, pp , [2]. Min-Seok Han; Jaehoon Choi; Multiband MIMO Antenna with a Band Stop Matching Cicuit fo Next Geneation Mobile Applications IEEE Confeences Publication Yea: 2009, Page(s): 1-4 [3]. AbuTaboush, H.F.; Al-Raweshidy, H.S.; Nilavalan, R.; Tiple band double U-slots patch antenna fo WiMAX mobile applications IEEE Confeences Publication Yea: 2008, Page(s): 1-3 [4]. S. aka, I.; Saka, P.P.; Chowdhuy, S.K.; A NOVEL COMPACT, MICROSTRIP ANTENNA WITH MULTIFREQUENCY OPERATION IEEE Confeences Publication Yea: 2009, Page(s): [5]. Hyeonjin Lee; Taehong Kim; Yeongseog Lim; Wide-Band Micostip Patch Antenna Design Fo LMDS Band IEEE Confeences Publication Yea: 2000, Page(s): [6]. Ka-Ming Mak; Hang Wong; Kwai-Man Luk; A Shoted Bowtie Patch Antenna With a Coss Dipole fo Dual Polaization IEEE Jounals Volume: 6 Publication Yea: 2007, Page(s): [7]. Xuan Wang; Zhengwei Du; Ke Gong; A Compact Wideband Plana Divesity AntennaCoveing UMTS and 2.4 GHz WLAN Bands IEEE Jounals Volume: 7 Publication Yea: 2008, Page(s): [8]. Capobianco, A.D.; Pigozzo, F.M.; Boscolo, S.; Midio, M.; Sacchetto, F.; Assalini, A.; Bunetta, L.; Zambon, N.; Pupolin, S.; A Novel Compact MIMO Aay based on PlanaYagi Antennas fo Multipath Fading Channels IEEE Confeences Publication Yea: 2010, Page(s): [9]. Le-Wei Li; Ya-Nan Li; Ke Xiao; Boadband and High-Gain Metamateial Micostip Anetnna Aays IEEE Confeences Publication Yea: 2010, Page(s): 1-4 [10]. Mookiah, P.; Dandeka, K.R.; Pefomance Analysis of Metamateial Substate Based MIMO Antenna Aays IEEE Confeences Publication Yea: 2008, Page(s):