SMALL SIZE EDGE-FED SIERPINSKI CARPET MICROSTRIP PATCH ANTENNAS

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1 Progress In Eletromgnetis Reserh C, Vol. 3, , 28 SMALL SIZE EDGE-FED SIERPINSKI CARPET MICROSTRIP PATCH ANTENNAS W.-L. Chen nd G.-M. Wng Rdr Engineering Deprtment Missile Institute of Air Fore Engineering University Snyun County, Shnxi Provine, 7138, P. R. Chin Astrt In this pper, we present novel tehnique to redue the size of edge-fed mirostrip pth ntenn. By ething the pth s the Sierpinski rpet, the resonnt frequeny n e lowered to lower vlues, nd this property n e employed to redue the size of the onventionl pth ntenn. The mesurement results show, the pth hieved mximum 33.9% size redution y the edge-fed Sierpinski Crpet mirostrip pth ntenn (SCMPA) of the seond itertion order, nd other performnes, suh s return loss ndwidth nd rdition ptterns, were virtully unhnged. 1. INTRODUCTION Aside from using high dieletri sustrtes [1], pplying shorting tehniques [2], nd inresing the eletril length of the ntenn y optimizing the shpe [3], there re minly two tehniques to redue the size of n edge-fed mirostrip pth ntenn. One is loding the edges of the pth with indutive elements [4, 5], nd the other is inserting the pitive elements into the pth [6, 7]. Koh frtl shpes hve een pplied to the edges of the pth to redue the size of the ntenn in [8 1], nd the essene of this tehnique flls into the indutive loding t the pth edges. And until now, there hs no reporting out the pplition of frtl theory to the tehnique of pitive loding. In this pper, we propose novel tehnique to pply frtl theory into this tehnique. By ething the pth s Sierpinski rpet of different itertion orders, the simultion results show the operting frequeny of the ntenn n e lowered to lower vlues, t the sme time mintining the ndwidth, rdition ptterns omprle to tht of norml edge-fed mirostrip pth

2 196 Chen nd Wng ntenn, nd this property n e used to redue the size of the pth ntenn. The proposed method is verified y the mesurement results. 2. SMALL SIZE EDGE-FED SCMPAS 2.1. Frequeny Lowering Property of the SCMPAs The Sierpinski rpet struture hs een pplied to ntenn engineering widely [11, 12], s shown in Fig. 1, ut until now, it hs not een used to redue the size of the edge-fed mirostrip pth ntenn. w w w Figure 1. Shemtis of the edge-fed Sierpinski rpet mirostrip pth ntenns of different itertion orders. S: Zeroth itertion order, S1: First itertion order, S2: Seond itertion order. As n e seen from Fig. 1, the dropped little retngulr elements re inside the pth, thus these elements n e onsidered s pitive elements. The whole struture of S1 nd S2 re somewht like the strutures loded y pitive elements s reported in [6, 7], nd this tehnique is expeted to lower the operting frequeny. As soon s the enter operting frequeny (f =1.8 GHz) nd the sustrte prmeters (er =4.3 nd h = 1 mm) given out, the design of the SCMPA n e omplished esily. Firstly, the onventionl edge-fed mirostrip retngulr pth ntenn n e designed followed the stndrd proedures given in [2]. Their optimum dimensions hve een determined through the optimiztion proess using FEM (finite element method)-sed Ansoft HFSS version 1.. Thus the physil prmeters of the onventionl edge-fed pth ntenn n e rrived t = 6 mm, =39.2 mm, =26.8 mm, nd w =1.9 mm. Seondly, the SCMPAs of different itertion orders n e designed y dropping elements on the pth s Sierpinski rpet, whose itertion ftor is 1/3, without hnging the physil prmeters of the pth, s shown in Fig. 1. Beuse of the mnufturing tolerne, the itertion order is limited to 2.

3 Progress In Eletromgnetis Reserh C, Vol. 3, Return Loss (db) S S1 S Frequeny (GHz) Figure 2. Simulted return losses of the designed edge-fed SCMPAs. Fig. 2 shows the simulted return loss, nd Fig. 3 shows the simulted rdition ptterns, of the designed edge-fed SCMPAs of different itertion orders, respetively, using Ansoft HFSS version 1.. As expeted y the uthors, the enter operting frequeny of the designed SCMPAs of different itertion orders shifted to lower vlues s the itertion orders inresed, s shown in Fig. 2. The enter operting frequeny of the onventionl edge-fed retngulr pth ntenn is 1.8 GHz, the edge-fed SCMPA of first itertion order is 1.5 GHz, nd the edge-fed SCMPA of the seond itertion order is 1.46 GHz. As lso shown in Fig. 3, side from deresing of the ntenn gin, whih is inevitle when the ntenn size deresed, the rdition ptterns of E-plne (phi = ) nd H-plne (phi = 9 ) of the designed SCMPAs of different itertion orders re omprle to eh other. From the ove nlysis, the frequeny lowering property of the SCMPAs is shown lerly, nd this property, s pitive loding tehnique, n e used to redue the size of the pth ntenns Smll Size Edge-Fed SCMPAs nd Experiment Results We designed the smll size edge-fed SCMPAs t 1.8 GHz, using the sustrte prmeters given ove. By optimizing the physil prmeters (,, nd ) of the SCMPAs of different itertion orders to mke the resonnt frequeny entered t 1.8 GHz, the vlues of these prmeters n e rrived suessfully, whih were s shown in Fig. 4. The prototypes of the designed smll size SCMPAs of different

4 198 Chen nd Wng Gin (db) S, f=1.8ghz S1, f=1.5ghz S2, f=1.46ghz Thet (deg) () Gin (db) S, f=1.8ghz S1, f=1.5ghz S2, f=1.46ghz Thet (deg) () Figure 3. Simulted rdition ptterns. () phi = deg, () phi = 9 deg. itertion orders were frited for experimentl use, nd Fig. 5 shows the photogrph of the frited prototypes. Fig. 6 shows the simulted nd mesured return losses, nd Fig. 7 shows the simulted nd mesured rdition ptterns, of the designed SCMPAs of different itertion orders. As n e seen from Fig. 4 nd Fig. 5, when resonted t sme frequeny, the size of the pth of SCMPA with the First itertion order

5 Progress In Eletromgnetis Reserh C, Vol. 3, =49.mm =33.mm =21. 8mm w=1.9mm = 48.mm = 32.4mm =21.5mm w=1.9mm w f =1.8GHz w f =1.8GHz () S1 () S2 Figure GHz. Shemtis of designed edge-fed SCMPAs resonted t Figure 5. Photogrph of the designed edge-fed SCMPAs resonted t 1.8 GHz Return Loss (db) S S S Frequeny (GHz) () Simulted results Return Loss (db) Frequeny (GHz) () Mesured results Figure 6. Return losses of the designed smll size SCMPAs. S S1 S2 is 68.75% of the size of the pth of onventionl pth ntenn, thus hieved 31.25% size redution, nd the size of the pth of SCMPA with the seond itertion order is 66.1% of the size of the pth of the onventionl pth ntenn, thus hieved 33.9% size redution. And from these oservtions, it is expeted tht the resonnt frequeny of the SCMPAs with itertion orders higher thn the seond itertion

6 2 Chen nd Wng () S () S1 () S2 Figure 7. SCMPAs. Rdition ptterns of the designed smll size edge-fed would remin lmost onstnt. As lso n e seen from Fig. 6 nd Fig. 7, the ntenn performnes suh s the return loss ndwidth nd the rdition ptterns of the SCMPAs re virtully unhnged.

7 Progress In Eletromgnetis Reserh C, Vol. 3, CONCLUSION In this pper, sed on the pitive loding tehnique, the frequeny lowering property of the edge-fed Sierpinski rpet mirostrip ntenns is studied. As expeted y the uthors, the edge-fed Sierpinski rpet mirostrip ntenns hve lower resonnt frequenies thn the onventionl pth ntenn, nd this property n y used to redue the pth size of the ntenn. When designed the edge-fed Sierpinski rpet mirostrip ntenns of different itertion orders t the sme frequeny, for Sierpinski rpet with 1/3 itertion ftor, the size of the pth n e redued to out 33.9% of the onventionl ounterprt without degrding the ntenn performnes, suh s the return loss nd rdition ptterns. The essene of this size redution tehnique is loding pitive elements inside the pth, nd to hieve muh greter redution in ntenn size, this tehnique n e used simultneously with other size redution tehniques, suh s indutive loding, using high dieletri onstnt sustrte, shorting tehnique, et. REFERENCES 1. Lo, T. K. nd Y. Hwng, Mirostrip ntenns of very high permittivity for personl ommunitions, 1997 Asi-Pifi Mirowve Conferene, , Wong, K.-L., Compt nd Brodnd Mirostrip Antenns, 1 7, John Wiely & Sons In., Hersovii, N., M. F. Osorio, et l., Minituriztion of retngulr mirostrip pthes using geneti lgorithms, IEEE Antenns nd Wireless Propgtion Letters, Vol. 1, 94 97, Reed, S., L. Deslos, C. Terret, nd S. Toutin, Size redution of pth ntenn y mens of indutive lods, Mirowve nd Optil Tehnology Letters, Vol. 29, No. 2, 79 81, Deslos, L., Y. Mhe, S. Reed, G. Poilsne, nd S. Toutin, Pth ntenn size redution y omining indutive loding nd short-points tehnique, Mirowve nd Optil Tehnology Letters, Vol. 3, No. 6, , Deslos, L., Size redution of pth y mens of slots insertion, Mirowve nd Optil Tehnology Letters, Vol. 25, No. 2, , Leon, G., R. R. Boix, nd F. Medin, A omprison mong different redued-size resonnt mirostrip pthes, Mirowve nd Optil Tehnology Letters, Vol. 29, No. 3, , 21.

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