Compact Microstrip UWB Bandpass Filter with Two Band-Notches for UWB Applications

Transcription

1 Progress In Eletromagnetis Researh Letters, Vol. 45, 25 30, 2014 Compat Mirostrip UWB Bandpass Filter with Two Band-Nothes for UWB Appliations Huaxia Peng 1, 2, Yufeng Luo 1, *, and Junding Zhao 3 Abstrat A new mirostrip ultra-wideband (UWB) bandpass filter (BPF) with dual sharply rejeted nothed bands based on E-shaped resonator is proposed in this paper. The basi UWB BPF is designed using two mirostrip interdigital oupled lines and one retangular path multiple-mode resonator (MMR). Then, to ahieve dual band-nothed performane, the proposed dual-mode E-shaped resonator is investigated and oupled to the retangular path multiple-mode resonator of the basi UWB BPF. To validate the design theory, a mirostrip UWB BPF with two noth-bands entered at the frequenies of 5.8 GHz and 8.0 GHz, respetively, is designed and fabriated. Both simulation and experimental results are provided with good agreement. 1. INTRODUCTION In 2002, the U.S. Federal Communiations Commission (FCC) authorized the unliensed use of ultrawideband (UWB, from 3.1 to 10.6 GHz) for a variety of appliations, suh as indoor and hand-held systems [1]. UWB BPFs, as one of the essential omponents of the UWB systems, have gained muh attention in reent years. There are many methods presented to design UWB bandpass filters [2 10]. For instane, multiple-mode resonator (MMR) [2, 3], defeted mirostrip struture (DMS) [4], defeted ground struture (DGS) [5, 6], multilayer oupled struture [7, 8], and the asaded low-pass/high-pass filters [9, 10] have been widely used to ahieve UWB harateristis. However, the existing wireless networks suh as 5.8 GHz WLAN signals and some 8.0 GHz satellite ommuniation systems signals an interfere with UWB systems, thus ompat UWB BPFs with multiple nothed bands are emergently required to rejet these interfering signals [11 21]. To ahieve a nothed band, a pair of radial impedane resonators are used in [11], and a stepped impedane resonator is employed in [12, 13]. On the other side, the embedding open-iruited stub is introdued in [14 16], and the wave s anellation theory is proposed in [17, 18] to blok unwanted existing radio signals. However, these methods an only ahieve one nothed band. Thus, a oupled simplified omposite right/left-handed resonator is used in [19], and a novel E-shaped resonator [20, 21] to get two nothed bands. However, these two designed methods are all that dual-mode resonator is oupled to the main transmission line of the initial UWB BPF to ahieve dual notehed bands. Additionally, double openiruit stubs are embedded into broadside-oupled stepped impedane resonators on middle layer in [22], and folded stepped impedane resonators are vertially-oupled to the seond layer in [23], two nothed bands an also be introdued into an UWB BPF. However, they are based on a multilayer struture and hardly ompatible with the existing mirowave-integrated iruit. In this paper, we present a new mirostrip ultra-wideband (UWB) bandpass filter (BPF) with dual sharply rejeted nothed bands based on E-shaped resonator is proposed in this paper. The Reeived 15 January 2014, Aepted 7 February 2014, Sheduled 13 February 2014 * Corresponding author: Yufeng Luo (yufengluo528@gmail.om). 1 Shool of Mehanial and Eletrial Engineering, Nanhang University, Nanhang , China. 2 Shool of Eletrial and Information Engineering, Hunan University of Tehnology (HUT), Zhuzhou , China. 3 Ministerial Key Laboratory of JGMT, Nanjing University of Siene and Tehnology (NUST), Nanjing , China.

2 26 Peng, Luo, and Zhao design proedures are as following: the basi mirostrip UWB BPF is designed using two mirostrip interdigital oupled lines and one retangular path multiple-mode resonator (MMR). Then, two bandnothed performane are ahieved by oupling the dual-mode E-shaped resonator to the retangular path multiple-mode resonator of the basi UWB BPF. The dual-nothed bands an be easily generated and realized by ontrolling the loations of even-odd modes resonane frequeny of the dual-mode stepped impedane resonator. Finally, the proposed filter is designed, fabriated and measured. Good agreement between measured and simulated results is ahieved. 2. DESIGN OF UWB BPF WITH NOTCHED BANDS Figure 1 shows the layout and equivalent iruit network of the designed UWB BPF with dual sharply rejeted nothed bands. Figure 1(a) omprises of two mirostrip interdigital oupled lines and one retangular path mutiple-mode resonator (MMR) embedded an E-shaped resonator. By forming quarter-wavelength parallel oupled lines and employing a retangular path MMR in the input and output ports, six transmission poles are introdued in the UWB passband to help the onstituted filter ahieve deeper rejetion skirts and wider bandwidths. The equivalent iruit network of the proposed filter is shown in Figure 1(b). The interdigital oupled lines an be equaled as two single transmission lines at two sides and a J-inverter suseptane in the middle. The E-shaped resonator oupled to the retangular path MMR setion of the basi UWB BPF an be modeled as two shunt series resonant branhes. l 2 w 1 w 0 l 1 d 1 d 2 (a) J J 50 Ω MMR 50 Ω -90 o -90 o L 2 L 1 C 1 C 2 (b) Figure 1. Layout and equivalent iruit network of the UWB BPF with dual nothed bands. (a) Layout. (b) Equivalent iruit network. To realize band-nothed harateristis, we introdue an E-shaped resonator into the basi UWB BPF. It should be mentioned that the E-shaped resonator an be equivalent to two shunt-onneted series resonane iruit when plaed next to the mirostrip line, i.e., it an result in dual band-nothed performane. This struture is simple and flexible for bloking undesired narrow band radio signals that may appear in UWB band. The introdued E-shaped resonator is omposed of a stepped impedane hairpin resonator with entrally loaded a short-ended stub. Figure 2 shows the layout of the E-shaped resonator oupled to the mirostrip line and its orresponding equivalent iruit. Sine the E-shaped struture is symmetrial to the A-A plane, the resonane properties of E-shaped resonator an be analyzed by the even-odd modes analysis method. Under mode exitation, the resonator eletrial field

3 Progress In Eletromagnetis Researh Letters, Vol. 45, distribution of the resonator exhibits either an even or an odd mode distribution property as shown in Figure 3. For the odd mode ondition, the eletrial fields exhibit an anti-symmetri distribution along the A-A axis and there is no eletrial field on the short-end stub as shown in Figure 3(a). While for the even mode, the eletrial fields exhibit a symmetri distribution along the A-A axis and the eletrial fields distribute on both the open-end and the short-end stubs of the resonator as shown in Figure 3(b). Thus, based on the eletrial field distribution property, the even-odd modes resonane w e1 A l e3 w e2 L 1 r e l e2 L 2 w egap Input l e1 Output C 1 C 2 A' Figure 2. Layout and equivalent iruit of the oupled E-shaped resonator. A A A' (a) A' (b) Figure 3. Eletrial field distribution of the E-shaped resonator. (a) Odd mode. (b) Even mode S (db) S (db) l e1+l e2 =7.4 mm l e1+l e2 =7.7 mm l e1+l e2= 8.0 mm Frequeny (GHz) (a) -25 l e3 =1.4 mm -30 l e3 =1.1 mm l e3 =0.8 mm Frequeny (GHz) (b) Figure 4. Simulated S-parameters of the oupled E-shaped resonator for various dimensions. (a) l e1 + l e2. (b) l e3.

4 28 Peng, Luo, and Zhao frequenies an be expressed as: f noth-even = f noth-odd = λ noth-even εeff = λ noth-odd εeff = 4(l e1 + l e2 + l e3 ) ε eff (1) 4(l e1 + l e2 ) ε eff (2) where λ noth is the wavelength of the enter frequeny of the nothed band, f noth is the enter frequeny of the nothed band, ε eff is the effetive dieletri onstant, and is the light speed in free spae. The frequeny harateristis of the oupled E-shaped resonator with various dimensions are investigated to validate the dual-mode resonant property as shown in Figure 4. It an be seen that the frequeny loations of the two noth-bands move down simultaneously as inrease the dimensions of l e1, l e2. This is beause the eletrial fields distribute on these two areas for both the even and the odd modes. When we derease l e3, only the frequeny loation of lower noth-band moves up. This is beause there is no eletrial fields distribute on the area of l e3 for the odd mode. Therefore, by appropriately adjusting the resonator dimensions, dual nothed bands an be ahieved at desired frequenies. 3. EXPERIMENTAL RESULTS The UWB BPF has been designed on substrate Rogers RT/duroid 5880 with a dieletri onstant of 2.2, thikness of 1.0 mm, and loss tangent of The strutural parameters for the optimal UWB BPF iruit are seleted as follows: (as illustrated in Figures 1 and 2): l 1 = 7.0 mm, l 2 = 8.4 mm, w 0 = 3.0 mm, w 1 = 0.5 mm, d 1 = 0.1 mm, d 2 = 0.5 mm, l e1 = 2.4 mm, l e2 = 5.6 mm, l e3 = 1.5 mm, w e1 = 0.4 mm, w e2 = 0.8 mm, w egap = 0.1 mm, and r e = 0.2 mm. Finally, the fabriated UWB BPF is measured with an Agilent N5244A vetor network analyzer. Simulated and measured sattering parameters are desribed in Figure 5 with good agreement. Referring to Figure 5, the fabriated UWB BPF has a passband from 3.0 to 10.3 GHz and the upper-stopband with 10 db attenuation is up to 16 GHz. The return loss is under 15 db over most part of the passband. For the two highly rejeted nothed bands, the measured results show that a better 15 db insertion loss at 5.8 and 8.0 GHz with the respetive 3 db FBW of 5.9% and 4.2% are ahieved. It should be mentioned that the UWB BPF is built up with good insertion loss and return loss for ahieving additional six transmission poles in the entire passband. The deviations of the measurements from the simulations are expeted mainly due to the refletions from the onnetors and the finite substrate. Figure 6 shows the photograph of the fabriated UWB BPF with dual sharply rejeted nothed bands. The overall size is about mm S-parameters (db) Sim. S 11 Sim. S 21 Mea. S 11 Mea. S Frequeny (GHz) Figure 5. Simulated and measured S-parameters of the designed UWB BPF with dual nothed bands. Figure 6. Photograph of the fabriated UWB BPF with dual nothed bands.

5 Progress In Eletromagnetis Researh Letters, Vol. 45, CONCLUSION A new mirostrip UWB BPF with dual highly rejeted nothed bands has been proposed in this letter. The basi UWB BPF is designed using two mirostrip interdigital oupled lines and one retangular path MMR. Then, dual-mode E-shaped resonator is investigated and oupled to the retangular path multiple-mode resonator of the basi UWB BPF to ahieved two nothed bands. The two nothed bands an be easily generated and realized by ontrolling the even-odd modes frequeny loations of the E-shaped resonator. For demonstration, a mirostrip UWB BPF is designed, simulated, and measured. Good agreement between the predited and measured results is obtained. Therefore, the proposed filter is very useful for modern UWB wireless ommuniation systems owing to its marked properties of simple topology, ompat size, and exellent performane. ACKNOWLEDGMENT This work was supported by the National Natural Siene Foundation of China under Grant No , the Jiangxi provine ground plan of siene and tehnology for insitution of higher eduation No. KJLD12050, the Jiangxi provine Siene and tehnology supporting projet No BBE50116, the Jiangxi provine Natural Siene Foundation of China under Grant No BAB206021, Sientifi Researh Fund of Jiangxi provine Nos and and 12748, Sienti Researh Fund of Hunan Provinial Eduation Department under Grant No. 13C022, and the Hunan Provine Nature Siene Foundation of China under Grant No. 14JJ2118. REFERENCES 1. FCC, Revision of Part 15, the Commission s rules regarding to ultra-wide-band transmission system, First Note and Order Federal Communiation Commission, ET-Doket , Zhu, H. and Q.-X. Chu, Compat ultra-wideband (UWB) bandpass filter using dual-stub-loaded resonator (DSLR), IEEE Mirow. Wireless Compon. Lett., Vol. 23, No. 10, , Qiang, L., Y.-J. Zhao, Q. Sun, W. Zhao, and B. Liu, A ompat UWB HMSIW bandpass filter based on omplementary split-ring resonators, Progress In Eletromagnetis Researh, Vol. 11, , Fallahzadeh, S. and M. Tayarani, A new mirostrip UWB bandpass filter using defeted mirostrip strutures, Journal of Eletromagneti Waves and Appliations, Vol. 4, No. 7, , Shobeyri, M. and M.-H. Vadjed-Samiei, Compat ultra-wideband bandpass filter with defeted ground struture, Progress In Eletromagnetis Researh, Vol. 4, 25 31, Naghshvarian-Jahromi, M. and M. Tayarani, Miniature planar UWB bandpass filters with irular slots in ground, Progress In Eletromagnetis Researh, Vol. 3, 87 93, Pakiaraj, D., K.-J. Vinoy, and A.-T. Kalghatgi, Analysis and design of two layered ultra wide band filter, Journal of Eletromagneti Waves and Appliations, Vol. 23, Nos. 8 9, , Wang, H., L. Zhu, and W. Menzel, Ultra-wideband bandpass filter with hybrid mirostrip/cpw struture, IEEE Mirow. Wireless Compon. Lett., Vol. 15, No. 12, , Comez-Garia, R. and J.-I. Alonso, Systemati method for the exat synthesis of ultra-wideband filtering responses using high-pass and low-pass setions, IEEE Trans. Mirow. Theory Teh., Vol. 54, No. 10, , Hao, Z.-C. and J.-S. Hong, UWB bandpass filter using asaded miniature high-pass and lowpass filters with multilayer liquid rystal polymer tehnology, IEEE Trans. Mirow. Theory Teh., Vol. 58, No. 4, , Xu, J., W. Wu, W. Kang, and C. Miao, Compat UWB bandpass filter with a nothed band using radial stub loaded resonator, IEEE Mirow. Wireless Compon. Lett., Vol. 22, No. 7, , 2012.

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