3D RFID Simulation and Design - Factory Automation

Transcription

1 3D RFID Simulation and Dein - Factory Automation x 3D RFID Simulation and Dein - Factory Automation Wei Liu and Min Mao Won * Sinaore Intitute of Manufacturin Technoloy Sinaore 71 Nanyan Drive, Sinaore Introduction The chater addree the roblem by reentin an analytical model for a 3-dimenional inle folded loo antenna with detection coverae in ace. Baed on the antenna theory, the inductance and imedance of the loo antenna i invetiated. Dein iue includin antenna tooloy, read rane, ta orientation, roximity of metal and other antenna are addreed to determine roer antenna for otimal erformance. The rooed dein i verified by field ditribution meaurement and imlemented a a RFID reader antenna for a mart helf alication. 1.1 RFID Sytem Radio Frequency Identification (RFID) i an automatic identification technoloy that tranmit the identity of an object wirelely uin radio wave. It i evolvin a a major technoloy enabler for item trackin and inventory manaement [1]. The reat aeal of RFID technoloy i that it allow information to be tored and read without requirin either contact or a line of iht between the ta and the reader [2]. Becaue uch technoloy conveniently diene with manual countin of item, it reatly reduce man-made error and thu imrove the accuracy of information. The RFID ytem conit of reader (alo known a interroator), ta (alo known a tranonder), and an information manain hot comuter [4] hown in Fiure 1. In a tyical communication equence, the reader emit a continuou radio frequency (RF) carrier ine wave. When a ta enter the RF field of the reader, the ta receive enery from the field. The ta i comoed of an antenna coil and a ilicon chi that include baic modulation circuitry and nonvolatile memory. When the RF field ae throuh an antenna coil, there i an AC voltae enerated acro the coil. Thi voltae i rectified to reult in DC voltae for the device oeration. The ta become functional when the DC voltae reache a certain level. After the ta ha received ufficient enery, it modulate the carrier inal accordin to the data tored on the ta. Finally, the information i relayed to a hot comuter.

2 314 Factory Automation Fi. 1. RFID ytem 1.2 RFID Smart Shelf Sytem A art of an inventory manaement in the context of factory, the RFID mart helf ytem i extremely ueful for trackin of material. By mountin a RFID reader antenna on each helf and by lacin a aive RFID ta with a unique erial number at each item, it would be oible to detect the reence of the individual item baed on the unique erial number aociated to it. Uer can then query the databae to determine the current location of the deired item. Such a RFID mart helf ytem will hel to enable a fat, accurate and reliable inventorycheckin and eliminate the need for manual tocktakin. Further, the information extracted from the item movement can be ued to tudy uae attern and detect miin item quickly. The mot common RFID mart helf alication i baed on the hih frequency (HF) band, which ha an A one of RFID alication, the mart helf ytem can be ueful in maintainin the factory inventory in real time. The ytem i baed on the inductive coulin at 13.56MHz. The read and write rane at thi frequency i uually not more than 1.5m, and mot aroriate for the bookhelf. Alication Alication Alication Databae Middleware Reader A D C Fi. 2. RFID mart helf ytem Senor Fi. 2. illutrate the comonent of a RFID mart helf ytem. The middleware in the hot manae the reader and iue command. The reader and ta communicate via RF inal.

3 3D RFID Simulation and Dein - Factory Automation 315 The ta receive and modifie the carrier inal enerated throuh the reader antenna. The reader receive the modulated inal from the antenna and return to the middleware. The alication read data from the middleware B, tore in the databae and udate the uer interface within the alication (Fiure 2). Another feature i aociated with the built-in enor for detectin book movement and thu eliminatin the need of contant manual monitorin on the alication. The enor i owered from the enery harveted from the radio wave of a reader. It i interated with RFID ytem throuh Analo Diital Converter (ADC). Fiure 7 how the ytem imlementation. In order for the RFID ytem to oerate effectively, the antenna lay a very crucial role. The dein of the antenna determine the amount of coulin effect, which in turn determine the communication between the reader and the ta. If the antenna of the reader and the ta are not deined correctly, inductive coulin will not occur and the deired ta will not be activated and the whole RFID alication to fail. Amon variou RFID frequency band for item level trackin, the mot widely ued frequency i MHz in the hih frequency (HF) band. Coniderin the fact that the wavelenth i roortional to the antenna dimenion, deinin electrically mall antenna in thi frequency with a wavelenth of meter i a very challenin tak. To overcome thi limitation, a ractical and olid RFID reader antenna i rooed with aroriate dimenion a a ractical and cheaer alternative [3]. A coer wire inle loo antenna wa choen for it ductility, olidity and erformance. Mot of the commercially available RFID mart helf ytem can only detect object (containin RFID ta) effectively in the two-dimenional (2D) field. Thi require the reader antenna and ta antenna to be in arallel lane. If they were in other orientation, the reader antenna may not be able to detect the reence of the ta antenna and thi will reatly reduce the readability. Thi retrict the way taed item can be laced on the helf and require multile antenna to cover a three dimenional reion. The efficiency and erformance of the antenna are reatly deendent on it dein tooloy. The tructure mut be deined uch that it can deliver maximum amount of enery to the deired detination in order to achieve efficient antenna erformance. The chater i divided into four art. Part one ive a brief dicuion on RFID technoloy and oint out the dein limitation for further imrovement. Part two decribe the RFID oeratin rincile and antenna dein. Part three detail the dein methodoloy of the reader antenna. Part four conclude the aer and rooe future reearch. 2. Antenna Dein The RFID reader oerate in the HF band at 13.56MHz and the reader antenna utilize the manetic field to tranfer ower to the battery-le ta durin readin and writin oeration. The aociated electrical field i not ued. The reader exect an antenna to be tuned to a center frequency of 13.56MHz and have an50 imedance. For otimum erformance, the reader matchin hould have a Voltae Standin Wave Ratio (VSWR) ratio of le than 1.2.

4 316 Factory Automation 2.1 Dein Guide Of all the antenna that can be ued to excite a manetic field, loo antenna are recommended a the mot uitable for eneratin the manetic field that i required to tranfer enery to the HF aive ta. But a number of iue have to be taken into conideration before the dein of an antenna can bein Proximity of Metal The reence of metal cloe to an antenna will reduce it erformance to ome extent. A the antenna i laced cloe to metal late,, the metal will detune the arameter and alo enerate eddy current to cancel the EM wave enerated by reader [14]. A a reult, the read ditance will dro. To overcome thi, the antenna mut be laced a certain amount of ditance from the metal Quality Factor The erformance of an antenna i related with it Quality (Q) factor. In eneral, the hiher the Q, the hiher the ower outut for a articular ized antenna. However, the bandwidth i inverely roortional to the Q [15]. Hence, there hould be a maximum value of Q. In the tet bed, ince the ta oerate with a data rate of 70 khz, the reader antenna circuit need a bandwidth of at leat twice of the data rate. Therefore, it need: The Q can be can be determined by: B khz (1) min 140 Thu, the maximum attainable Q i obtained from formula (2), Q f 0 (2) B Q max 13.56MHz 96.8 (3) 140KHz Preence of Other Antenna The reence of other antenna will alter the way a ytem erform becaue of coulin between the antenna. In thi tet bed where there are multile helve tandin toether, each embedded with one antenna, there would be interference amon thee cloely laced antenna. 2.2 Tooloy Determination The arameter of the loo antenna that can be choen are hae, dimenion, number of turn and wire diameter. Thee will be dicued in the followin ection and will lead to a dein methodoloy.

5 3D RFID Simulation and Dein - Factory Automation Shae A novel 3-dimenional folded rectanular loo antenna i rooed to enerate a manetic field of at leat certain trenth within interroation reion. Fiure 3 illutrate the chematic of deined antenna tooloy. The feed-oint i located at the bae where the electrical current enter and leave the antenna. The two folded art of the antenna hel to enhance the manetic field to detect ta lace in different orientation. After enterin the feed-oint, the current branche into two identical tream which flow throuh the ret art of the antenna and meet at the exit oint. Since the current flowin throuh two arallel folded art are in the ame direction, the mutual inductance i oitive. Therefore, the manetic field in x direction i trenthened. Z Y X Fi. 2. Antenna tooloy Number of Turn For readin a loner raner, one way i to achieve a larer B field. Thi can be done by increain the number of amere-turn ( NI ). However, there are drawback to thi otion a the more turn the antenna i, the le ortable and more exenive the reader become. The conequence of increain ( NI ) i a larer inductance in the reader antenna circuit that increae a the quare of the number of turn. A hih inductance load reult in lare amount of reflected ower (back EMF) a well a a lare imedance that varie inificantly. Therefore, it i imortant to kee ( NI ) a mall a oible while achievin the minimum B field needed for the deired read rane. For a loo antenna, fed by a voltae ource, dicardin the mall ohm and radiation reitance with reect to formula i deduced: L, the followin V V V L NL N 1 NL (4) N 1 where N = number of turn I = flowin current L = inductance of a loo of the ame ize with only one turn N 1

6 318 Factory Automation Hence, to maximize the manetic field trenth B, we need to maximize NLN 1, which mean N 1 and keein LN 1 mall Wire Diameter Fiure 4 illutrate the tructure of loo antenna tooloy. Fi. 4. Inductance of rectanular loo If reader antenna i made of a rectanular loo comoed of a thin wire, it inductance can be calculated by the followin formula [16] 2A 2A L0 4lb ln la ln 2 a lc ( la lb ) ( nh ) a( lb lc ) a( la lc ) (5) Where the unit are all in cm a = radiu of wire l c = A = a b l l l 2 2 a b l Hence, uin a wire with a lare diameter hel to reduce L. 2.3 Imedance Matchin Since the reader antenna i deined for a mart helf alication, the dimenion mut fit the mechanical contraint of the bookhelf (100cm*30cm*40cm). The manetic field created by the antenna i ued to ower the ta aociated with the book within the bookhelf and the amount of enery induced in each ta i roortional to the trenth of the manetic field ain throuh the ta loo. The larer the reader antenna loo i, the more current carryin art add a contribution to the manetic field. If the loo become too lare, however, thee contribution become very weak due to the lare ditance from the current carryin art to the ta. Furthermore, if the total wire lenth of the loo become a coniderable art of the wavelenth of 22.12m, the tandin wave will caue multile

7 3D RFID Simulation and Dein - Factory Automation 319 reonance and decreae the total field [3, 11]. Hence, the antenna dimenion i determined exerimentally to rovide the ufficient manetic field Maximum Power Theorem The antenna and the enerator can be rereented by an equivalent circuit [17] a hown in Fiure 5. The imedance of the antenna i where Z A = R = A X = A Z A RA jx A (6) antenna imedance at terminal a-b (ohm) antenna reitance at terminal a-b (ohm) antenna reactance at terminal a-b (ohm) In eneral the reitive art of (6) conit of two comonent; that i where R r = R = L radiation reitance of the antenna lo reitance of the antenna RA Rr RL (7) Fi. 5. Antenna equivalent circuit To find the amount of ower delivered tor for radiation and the amount diiated in a heat ( by r 2 I R L ), we firt need to find the current develoed within the loo which i iven 2 I V V V Z Z Z ( R R R ) j( X X ) t A r L A ( A) R L (8)

8 320 Factory Automation and it manitude by I V ( R R R ) ( X X ) r L A wherev i the eak enerator voltae. The ower delivered to the antenna for radiation i iven by V R r Pr I Rr ( ) 2 2 A 2 2 ( Rr RL R ) ( X A X ) and the diiated a heat by (9) (10) V R L PL I RL ( ) 2 2 W 2 2 ( Rr RL R ) ( X A X ) (11) The remainin ower i diiated a heat on the internal reitance R of the enerator, and it i iven by 2 V R P ( ) 2 2 W 2 ( Rr RL R ) ( X A X ) The maximum ower delivered to the antenna occur when we have conjuate matchin; that i when (12) For thi cae Rr RL R (13) X X (14) A 2 2 V R V Rr R L P Pr PL ( Rr RL ) 8 ( Rr RL ) The ower ulied by the enerator durin conjuate matchin i * 1 * 1 V V 1 P V I V 2 2 2( Rr RL ) 4 ( Rr RL ) 2 (15) (16)

9 3D RFID Simulation and Dein - Factory Automation 321 Of the ower that i rovided by the enerator, half i diiated a heat in the internal reitance ( R ) of the enerator and the other half i delivered to the antenna. Thi only haen when conjuate matchin i alied Two-Comonent Matchin Network Fiure 6 dilay the antenna imedance, which i1.585 j119.74( ) at 13.56MHz. In order to achieve maximum ower tranfer, it i required to match the imedance of the load to that of the ource (50 ). Thi i accomlihed by incororatin additional aive network connected in between ource and load. Fi. 6. Antenna imedance without matchin network The two-comonent network [18], alo know a L-tye due to the element arranement, i ued to tranform the load imedance ( Z load ) to the deired inut imedance ( Z in ). The comonent are alternatively connected in erie and hunt confiuration, a hown in Fiure 7, which deict eiht oible arranement of caacitor and inductor. Fi. 7. Eiht oible confiuration of the two-comonent matchin network

10 322 Factory Automation There are two broad aroache in deinin a matchin network. To derive the value of the element analytically To rely on the Smith Chart a a rahical dein tool The firt aroach yield very recie reult. Alternatively, the econd aroach i more intuitive, eaier to verify, and fater for an initial dein, ince it doe not require comlicated comutation. Both aroache are alied a a cro-checkin Analytical Aroach Fi. 8. L-tye matchin network dein A hown in Fiure 8, the mall loo antenna i rimarily inductive and it can be rereented by a lumed element equivalent circuit [17]. where R r = R = ac L Z R jx ( R R ) jx (17) radiation reitance in in in r ac L AC reitance of loo conductor X = inductive reactance = L0 The caacitor, C C are ued to tune the antenna imedance to be 50 for maximum ower efficiency. Thi i accomlihed by chooin, C C accordin to 1 ( jx ) 50 ( ) j 1 X R jx in in 1 ( jx ) 50 ( ) jr X X in in X ( R jx ) in in (18) (19)

11 3D RFID Simulation and Dein - Factory Automation 323 X ( R jx )( X X jr ) ( jx ) 50 ( ) in in in in 2 2 ( X X in ) Rin X R j( X X X X X R ) ( jx ) 50 ( ) in in in in 2 2 ( X X in) Rin (20) (21) The real art i X R ( X X ) R 2 in in in (22) The imainary art cancel out X X X X X R in in in 2 2 ( X X in) Rin X (23) Given R 1.585, X , it i calculated that X 670.7, X 145.8, which in ic 17.5 F, C 80.5F. in Grahical Aroach The Smith Chart i ued for raid and relatively recie dein of the matchin circuit. The aeal of thi aroach i that it comlexity remain almot the ame indeendent of the number of comonent in the network. Moreover, the arameter choice and it value ainment can be intantaneouly dilayed at art of the Smith Chart on the comuter creen. Fiure 9 illutrate the te of L-tye matchin network dein by uin the Smith Chart a a rahical tool. The initial data oint Z i1.585 j L. Since the firt comonent i a hunt caacitorc, the total imedance of thi arallel combination i oitioned omewhere on the circle of contant conductance in reen color that ae throuh the oint Z. Next, the econd caacitor C i added in erie with the arallel combination L of Z andc. The reultin imedance will move alon the circle of contant reitance in L red color. For maximum ower ain it i required that an outut imedance of the matchin network connected to the antenna to be equal to the comlex conjuate of the tranmitter imedance. Thi circle ha to a throuh the center of the Smith Chart which i 50.

12 324 Factory Automation 1. Z L 3. Serie Caacitor C 2. Shunt Caacitor C Fi. 9. Matchin network dein with Smith Chart The interection of two circle in the Smith Chart determine the imedance formed by the hunt connection of antenna and caacitor. Readin from the Smith Chart, it i found that thi imedance i aroximately ZLC 49.4 j The correondin admittance i YLC j The admittance of antenna i YL j Therefore, the ucetance of the hunt caacitor i jb Y Y j 3 LC L The reactance of the erie caacitor i jx 50 Z j Finally, the actual value arec 17.5 F, C 80.5F. The reult of both analytical and rahical aroache were found to correlate quite well. LC 3. Antenna Methodoloy Develoment The 3-dimenional inle-loo antenna i built uin coated coer wire a hown in Fiure 10. The diameter of electrical wire i exreed a the American Wire Gaue (AWG) number. The aue number i inverely roortional to diameter, and the diameter i

13 3D RFID Simulation and Dein - Factory Automation 325 rouhly doubled every ix wire aue. Since there i no coated wire for AWG 1-7, AWG 8 i the bet choice available with laret diameter. The antenna i then attached to a iece of foam bae to ive the antenna riidity and mechanical uort. Without the foam bae, the tructure of the antenna may not be uniform throuhout the tetin roce (bendin of wire etc) and thi will have an undeirable imact on the inductance of the antenna and in turn may caue the antenna to be unreliable. Foam i choen a it i a non-metallic material therefore it will not have any manetic effect on the antenna. The feed oint i made in the middle of the antenna and it will be ued to rovide interface with the RFID reader/writer. Fi. 3. Prototye of RFID reader antenna The theoretical derivation rovide a ood uide to imlement the matchin network. In ractice, a variable caacitor with a lare rane e..12 i ued to achieve the 80 F deired rane. Once the matchin ha been achieved, it i removed and meaured and a larer fixed caacitor i ued, toether with a maller variable caacitor, to allow for fine turnin. Fiure 11 how the actual L-tye matchin network where the erie branch conit of one fixed caacitor of 5 F with one variable caacitor of 311F and the hunt branch i comoed of two arallel caacitor of 47 F each with one variable caacitor of311f a well. Fi. 4. L-tye matchin network

14 326 Factory Automation 3.1 Antenna Meaurement The antenna erformance i aeed by meaurin followin arameter Return Lo and SWR After the antenna i connected to the matchin circuit and fine tuned and matched to 50 ohm, we meaured the imendence and SWR value of the antenna. Fiure 12 dilay the imedance i around 50. And the antenna ha a return lo i dB and SWR i a how in Fiure 13. Fi. 12. Antenna imedance with matchin network Fi. 13. Antenna SWR Both reult indicate that maximum amount of enery are tranmitted to the antenna and thi will enure that data lo are reduced to the minimum.

15 3D RFID Simulation and Dein - Factory Automation Quality Factor The Q factor rereent the amount of AC reitance of a ytem at reonance and it can be determined by meaurin the 3-dB bandwidth of the antenna near field reone, frequency wee between 13 MHz and 14 MHz. Fiure 14 dilay the meaurement of Q factor. At 13.56MHz labeled by marker 2, the antenna exhibit the reonance. At 13.46MHz and 13.66MHz, the lower and uer -3dB oint are found and recorded. The three frequencie can be ued in the formula (2): f Q f 2 f 1 (24) The Q value i maller than the uer limit Fi. 14. Q factor meaurement Field Ditribution Meaurement The antenna model mut be able to roduce an electromanetic field havin a manitude of at leat an interroation threhold of a ta for the entire interroation reion. The manetic field trenth of the loo antenna at a ecified ditance determine the readin rane of an RFID ytem with rior elected RFID reader and ta. The troner the manetic field, the larer the detection rane. Strenth of the meaured field i rereented by the induced voltae. The ta utilized in the exeriment i activated only when the induced voltae i reater than 200mV. Manetic field intenity of the loo antenna i meaured at varyin tet oint [19]. The meaurement i conducted by uin ocillocoe a hown in Fiure 15.

16 328 Factory Automation Ocillocoe Fi. 15. Setu for field ditribution meaurement Fiure 16 how that at the mid cro ection x = 44 cm of the antenna, the field ditribution in X-direction varie inificantly with the z coordinate. The loo antenna enerate tron manetic field in the reion cloer to the antenna (z 20 cm), while the field decreae a ditance from the antenna increae. The antenna i able to detect the ta within 30 cm heiht of the antenna. Fi. 16. Manetic field ditribution in x direction Fiure 17 reent that acro the mid lane y = 20 cm of the antenna, the manetic field in Y-direction lihtly achieve the eak value at both ede of and lihtly dro in the middle of the antenna for the ame heiht. A ditance from the antenna increae, the field decreae. There i a black reion between x = 33 cm and x = 55 cm a z 15 cm.

17 3D RFID Simulation and Dein - Factory Automation 329 Fi. 17. Manetic Fieldditribution in y direction Fiure 18 illutrate the manetic field ditribution in Z-direction acro the lane z = 18 cm above the antenna. The antenna roduce tron manetic field at both ede. There i a black reion in the middle of the antenna. Fi. 18. Three-dimenional field ditribution in z direction

18 330 Factory Automation Antenna Read Ditance Fiure 19 illutrate the manetic field intenity in x direction meaured by movin the ta alon three different line, tartin from oint (y = 10, z = 5), (y = 10, z = 15), (y = 10, z = 25). Thee three line are rereentative of all oition where the book are laced vertically. The manetic field intenity i tron at both ide but dro raidly a movin toward the center. In the middle of the antenna, the field become tron aain. Fi. 19. Manetic field intenity alon different line in x direction Fiure 20 how the manetic field intenity in y direction meaured by movin the ta alon three different line, tartin from oint (x = 22, z = 15), (x = 44, z = 15), (x = 66, z = 15). Thee three line are rereentative of tyical oition where book are laced erendicularly. The two line in the uer reion of the diaram differ in the trace of the line in the lower reion. Fi. 20. Manetic field intenity alon different line in y direction

19 3D RFID Simulation and Dein - Factory Automation 331 Fiure 21 reent the manetic field intenity in z direction meaured by movin the ta alon three different line, tartin from oint (x = 22, y = 10), (x = 44, z = 10), (x = 66, z = 10). Thee three line are rereentative of tyical oition where book are laced horizontally. The further away from the antenna, the weaker the field become. Fi. 21. Manetic field intenity alon different line in z direction Variou Orientation The reult from the above ection were then ued to develo a rototye for RFID book helf alication. The rototye wa able to detect book in a number of different orientation within the 3D reion with a rane of 44 cm from the vertical antenna a hown in Fiure 22. Fi. 22. rototye of mart book helf

20 332 Factory Automation 4. Concluion Thi chater ha reented and invetiated loo antenna and enor circuit for HF RFID mart helf alication. The iue includin ta orientation, read rane, roximity of metal and other antenna are aroached durin the antenna dein. A 3-dimenional hae of inle turn loo antenna i rooed. The otimum antenna ize wa determined a a trade-off between the manetic field trenth and mechanical contraint. The antenna model ha been uccefully ued to confiure an HF RFID mart helf rototye. The erformance tet ha hown that the antenna i caable of achievin the deired reult. The further reearch followin thi roject would involve interatin more than one bookhelf into the mart helf alication. 5. Reference [1] J. Landt, "The hitory of RFID," Potential, IEEE, vol. 24,. 8-11, [2] R. Want, RFID Exlained: A Primer on Radio Frequency Identification Technoloie: Moran & Clayool Publiher, [3] D. Miron, Small Antenna Dein: Newne, [4] K. Finkenzeller, RFID Handbook: Fundamental and Alication in Contactle Smart Card and Identification, 2nd ed. New York: Wiley, [5] V. Chawla and H. Don Sam, "An overview of aive RFID," Communication Maazine, IEEE, vol. 45, , [6] F. Fuchini, C. Pieranti, F. Paolazzi, and G. Falciaecca, "On the Efficiency of Load Modulation in RFID Sytem Oeratin in Real Environment," Antenna and Wirele Proaation Letter, IEEE, vol. 7, , [7] H. K. Ryu and J. M. Woo, "Miniaturiation of rectanular loo antenna uin meander line for RFID ta," Electronic Letter, vol. 43, , [8] S. C. Q. Chen and V. Thoma, "Otimization of inductive RFID technoloy," in Electronic and the Environment, Proceedin of the 2001 IEEE International Symoium on, 2001, [9] J. Nummela, L. Ukkonen, L. Sydanheimo, and M. Kivikoki, "13,56 MHz RFID antenna for cell hone interated reader," in Antenna and Proaation Society International Symoium, 2007 IEEE, 2007, [10] T. Intrument, "HF Antenna Dein Note Technical Alication Reort," , Setember [11] W. Aert, E. De Mulder, B. Preneel, G. A. E. Vandenboch, and I. Verbauwhede, "Deendence of RFID Reader Antenna Dein on Read Out Ditance," Antenna and Proaation, IEEE Tranaction on, vol. 56, , [12] C. Klaf, A. Mioni, G. Hofer, G. Holwe, and W. Karl, "Imrovement in Oerational Ditance in aive HF RFID Tranonder Sytem," in RFID, 2008 IEEE International Conference on, 2008, [13] D. C. Yate, A. S. Holme, and A. J. Burdett, "Otimal tranmiion frequency for ultralow-ower hort-rane radio link," Circuit and Sytem I: Reular Paer, IEEE Tranaction on, vol. 51, , 2004.

21 3D RFID Simulation and Dein - Factory Automation 333 [14] Q. Xianmin and C. Zhi Nin, "Proximity Effect of Metallic Environment on Hih Frequency RFID Reader Antenna: Study and Alication," Antenna and Proaation, IEEE Tranaction on, vol. 55, , [15] S. R. Bet, "A dicuion on the quality factor of imedance matched electrically mall wire antenna," Antenna and Proaation, IEEE Tranaction on, vol. 53, , [16] Y. Lee and P. Sorrell, "AN680: MicroID MHz RFID Sytem Dein Guide," Microchi Technoloy Inc., [17] C. A. Balani, Antenna Theory: Analyi and Dein, 3rd ed. Hoboken, N.J.: Wiley- Intercience, [18] R. Ludwi, P. Bretchko, and G. Bodanov, RF Circuit Dein: Theory and Alication, 2nd ed.: Prentice Hall, [19] A. Cai, Q. Xianmin, C. Zhi Nin, and L. Boon Ken, "Performance aement of rinted RFID reader antenna," in Antenna and Proaation Society International Symoium, 2007 IEEE, 2007, [20] Noax, "Exeriment #52 SWR Meter," QST, May [21] C. Bowick, RF Circuit Dein. Burlinton, MA: Newne, 1997.

22 334 Factory Automation

23 Factory Automation Edited by Javier Silvetre-Blane ISBN Hard cover, 602 ae Publiher InTech Publihed online 01, March, 2010 Publihed in rint edition March, 2010 Factory automation ha evolved inificantly in the lat few decade, and i today a comlex, interdicilinary, cientific area. In thi book a election of aer on toic related to factory automation i reented, coverin a broad ectrum, o that the reader may become familiar with the variou field, and alo tudy them in more deth where required. Within variou chater in thi book, ecial attention i iven to ditributed alication and their ue of network, ince it i one of the mot relevant ubject in the evolution of factory automation. Different Medium Acce Control and network are analyzed, while Ethernet and Wirele network are looked at in more detail, ince they are amon the hottet toic in recent reearch. Another imortant ubject i everythin concernin the increae in the comlexity of factory automation, and the need for flexibility and interoerability. Finally the ue of multi-aent ytem, advanced control, formal method, or the alication in thi field of RFID, are additional examle of the idea and diciline that exert around the world have analyzed in their work. How to reference In order to correctly reference thi cholarly work, feel free to coy and ate the followin: Wei Liu and Min Mao Won (2010). 3D RFID Simulation and Dein - Factory Automation, Factory Automation, Javier Silvetre-Blane (Ed.), ISBN: , InTech, Available from: htt:///book/factory-automation/3d-rfid-imulation-and-dein-factory-automation InTech Euroe Univerity Camu STeP Ri Slavka Krautzeka 83/A Rijeka, Croatia Phone: +385 (51) Fax: +385 (51) InTech China Unit 405, Office Block, Hotel Equatorial Shanhai No.65, Yan An Road (Wet), Shanhai, , China Phone: Fax: