A New Broadband Microstrip-to-SIW Transition Using Parallel HMSIW

Transcription

1 JOURNAL OF ELECTROMAGNETIC ENGINEERING AND SCIENCE, VOL. 12, NO. 2, 171~175, JUN ISSN (Online) ISSN (Print) A New Broadband Mirostrip-to- Transition Using Parallel HM Dae-Keun Cho Hai-Young Lee Abstrat In this work, a new mirostrip-to-substrate integrated waveguide () transition using the parallel half-mode substrate integrated waveguide (HM) is proposed. The proposed transition onsists of three setions : a mirostrip, parallel HMs, and an. By inserting the parallel HMs setion between the mirostrip setion and the setion, the proposed transition an improve the return loss harateristis of the near ut-off frequeny beause the HMs setion has a lower ut-off frequeny than the setion (8.6 GHz). The lower ut-off frequeny is ahieved through gradual eletromagneti field mode hanges for a low refletion. The measured return loss is less than 20 db in the of 9.1~16.28 GHz freqeuny range for the bak-to-bak transition. The measured insertion loss is within 1.6 db for the bak-to-bak transition. The proposed transition is expeted to play an important role in wideband iruits fed by a mirostrip. Key words: Broadband, Half-Mode Substrate Integrated Waveguide, Substrate Integrated Waveguide, Transition. Ⅰ. Introdution A substrate integrated waveguide (), onstruted with two parallel rows of via-holes in a metalized planar substrate, has beome an attrative transmission struture beause of its manufaturing simpliity and its benefits from the low prodution ost of the PCB proess, ompat size, low loss, and high quality fator. The has been presented in the form of filters, ouplers, dividers, and antennas. However, these omponents must be interonneted with planar strutures to provide the means for measuring to allow the omponents to be ompletely integrated with planar ative iruits [1], [2]. Typial transitions for the have been presented, inluding the tapered mirostrip transition, the CPW transition, and the retangular waveguide transition. The tapered mirostrip transition has been widely used; it is a very simple struture and has low loss. The performane of the transition is better when ompared to other mirostrip transitions [3]~[6] or oplanar transitions [7], [8]. However, the onventional tapered mirostrip transition is unable to over the omplete fundamental-mode bandwidth. The operating bandwidth of the ommonly begins after some frequeny band above the 's ut-off frequeny. Thus, signals oupying the near ut-off frequeny region experiene distortion due to the variation in the propagation delay for different spetral omponents of the signal [9]. This work presents a new mirostrip-to- transition using the parallel half-mode substrate integrated waveguide (HM). The proposed transition onsists of the parallel HMs setion between the mirostrip setion and the setion. The proposed transition an redue the disontinuity effet due to the apaitane effet in the HMs setion and the gradual mode mathing in the entire struture. The proposed transition has better mathing harateristis than the onventional tapered mirostrip transition in the fundamental-mode bandwidth region. Thus, the ombination of these three setions allows us to obtain broadband harateristis over the omplete fundamental-mode bandwidth. Ⅱ. Struture and Design Fig. 1 shows the proposed transition as bak-to-bak from a mirostrip line to an within the same dieletri substrate. The transition onsists of three setions: the mirostrip line setion, the parallel HMs Manusript reeived April 30, 2012 ; Revised May 30, 2012 ; Aepted June 1, (ID No J) Mirowave Appliation Laboratory, Ajou University, Suwon, Korea. Corresponding Author : Hai-Young Lee ( hylee@ajou.a.kr) This is an Open-Aess artile distributed under the terms of the Creative Commons Attribution Non-Commerial Liense ( by-n/3.0) whih permits unrestrited non-ommerial use, distribution, and reprodution in any medium, provided the original work is properly ited. Copyright The Korean Institute of Eletromagneti Engineering and Siene. All Rights Reserved. 171

2 JOURNAL OF ELECTROMAGNETIC ENGINEERING AND SCIENCE, VOL. 12, NO. 2, JUN Fig. 1. Proposed transition. setion, and the setion. The ut-off frequenies of the mode and the HMs are simply alulated as follows [2], [10]. f 1 = 2p me mp 2 np ( ) + ( ) 2 a b (1) Fig. 2. Configuration of the optimized transition(unit: mm). f HM = 4 e a r HM (2) The does not allow TM modes guidane. Therefore, single-mode bandwidth is guaranteed with the TE10 mode related to the TE 20 mode [11]. Thus, similar to the onventional retangular waveguide, the bandwidth is defined between 1.25 f and 1.9 f ( f : fundamental-mode retangular waveguide ut-off frequeny) [12]. Therefore, the proposed transition should improve the mathing harateristis between f and 2 f so that it has the omplete fundamental-mode bandwidth. By inserting the parallel HMs setion between the mirostrip setion and the setion, the proposed transition an improve the return loss harateristis of the near ut-off frequeny beause the HMs setion has a lower ut-off frequeny than the setion (8.6 GHz). This is ahieved through gradual eletromagneti field mode hanges to obtain a low refletion ( S 11< 20 db). Fig. 2 is the geometry of the optimized transition. The setion is designed to have a ut-off frequeny (8.6 GHz). For impedane mathing, the mirostrip taper onnets the mirostrip setion to the parallel HMs setion. Using formulas (1) and (2), the width of the is 12mm and the width of the HM is 6mm. The proposed transition ahieves impedane mathing and mode transformation between different transmission setions (the mirostrip, the parallel HMs, and the ). Fig. 3 shows the parallel HM- s setion. It has two HMs and via-holes between the parallel HMs. By inserting the via-holes on the parallel HMs setion, the mathing harateristis of the proposed transition are improved by the a- Fig. 3. Configuration of the parallel HM setions. Fig. 4. Simulated ut-off frequeny versus the via-hole diameter. paitane effet between the parallel HMs and the via-holes. Fig. 4 shows the simulated ut-off frequenies to the via-holes diameter in the enter of the parallel HMs setion. Using a 3D simulation tool (HFSS), the design struture is a parallel HMs struture in a bak-tobak type from the mirostrip line to the HMs. This is onfirmed by varying the diameter of the via-hole. Fig. 4 shows the simulated results of the via diameter 172

3 CHO and LEE : A NEW BROADBAND MICROSTRIP-TO- TRANSITION USING PARALLEL HM from 0 mm to 1 mm. The diameter of the via-pad is designed 0.2 mm larger than the diameter of the via-hole in the enter of the parallel HMs setion. In Fig. 4, when the diameter of the via-holes inreases, the ut-off frequeny is lowered beause of the apaitane effet. The HMs setion with the via-holes has a lower ut-off frequeny than the setion (8.6 GHz). The proposed transition mathes the mathing at a lower frequeny than 8.6 GHz. By inserting via-holes between the HMs, the parallel HMs setion with the via has a lower fundamental mode ut-off frequeny than the setion in the same width (12 mm). Thus, the proposed transition an improve the mathing harateristis beause the dispersive band moves to a lower frequeny than the original guard-band. 2-1 Gradual Mode Transformation Aurate impedane mathing and omplete mode transformation between different transmission lines are important for broadband harateristis. Thus, the transition is important to transform the eletromagneti field mode. Fig. 5 illustrates the proposed transition. It onsists of 4 setions: the mirostrip setion (A-A'), the dividing setion (B-B'), the parallel HMs setion (C- C'), and the setion (D-D'). The proposed transition an improve the mathing harateristis beause of the gradual mode mathing of the entire struture. At first, the quasi-tem mode in the mirostrip setion gradually hanges to the quasi- TE10 mode in the parallel HMs setion and the quasi- TE 10 in the parallel HMs setion gradually hanges to TE 10 in the setion. Progressive hanges in the eletromagneti field mode are ahieved through the gradual hanges to obtain a low refletion ( S 11 < 20 db). 2-2 Simulated Results The proposed transition has been optimized with a 3-D FEM simulator (HFSS), as shown in Fig. 1, where a Taoni TLY-5 is used, with e r =2.2, tan d =0.0009, thikness=0.787 mm. The onventional tapered mirostrip transition and the proposed transition are 48 mm and 49.2 mm long, respetively. Fig. 6 shows the simulated results of the onventional tapered mirostrip transition and the proposed transition. Return loss harateristis of less than 20 db are observed at the 11~18.6 GHz frequeny range (the onventional tapered mirostrip transition) and the 9.2~21.74 GHz frequeny range (the proposed transition) for the bak-to-bak transition. As simulated results, the insertion loss of the setion without the HMs setion and the transition setion is 0.06 db at 10 GHz. In the bandwidth range of the proposed transition, the simulated insertion loss of the bak-to-bak transition is within 1 db while that of the onventional tapered mirostrip is within 0.99 db. The mathing harateristis of the proposed transition are better than the onventional tapered mirostrip transition from f (8.6 GHz) to 1.25 f (10.75 GHz). Therefore, the proposed struture has good mathing harateristis from 1.06 f to 2.52 f. In the bandwidth ran- (a) Top view (b) The E-field gradation Fig. 5. The struture of the proposed transition. Fig. 6. Simulated S-parameters of the proposed transition and the onventional tapered mirostrip transition. 173

4 JOURNAL OF ELECTROMAGNETIC ENGINEERING AND SCIENCE, VOL. 12, NO. 2, JUN ge, the insertion loss is the same for the onventional tapered mirostrip transition and the proposed transition. The HM struture relies on suppression of the dominant higher-order mode TE 20. The TE 20 mode annot propagate in suh an HM struture so that the bandwidth harateristis of the proposed transition an be enhaned [11]. A return loss of better than 25 db is ahieved in the omplete fundamental-mode bandwidth (from 1.25 f to 1.9 f ). Ⅲ. Measured Results Fig. 7 shows the fabriated bak-to-bak devie of the designed mirostrip-to-hm-to- transition. The bak-to-bak transitions are measured with the vetor network analyzer (up to 20 GHz). Their lengths are approximately the same. Fig. 8 shows the measured results of the onventional tapered mirostrip transition and the (a) (b) Fig. 7. Photographs of (a) the onventional tapered mirostrip transition and (b) the proposed transition. proposed transition. A return loss of less than 20 db was been observed in the frequeny range of 0.22~14.9 GHz (the onventional tapered mirostrip transition) and 9.1~16.28 GHz (the proposed transition) for the bakto-bak transition. A return loss of less than 15 db was observed in the frequeny range of 9.24~15.38 GHz (the onventional tapered mirostrip transition) and 9.02 ~18.13 GHz (the proposed transition) for the bak-tobak transition. In the bandwidth range of the proposed transition, the measured insertion loss of the bak-tobak transition was within 1.6 db while that of the onventional tapered mirostrip was within 1.2 db. As expeted, the proposed transition was the improved return loss harateristis. Ⅳ. Conlusions A new mirostrip-to- transition using the parallel half-mode is proposed. This transition struture onsists of three parts: the mirostrip setion, the parallel HMs setion, and the setion. Due to the gradual mode mathing and the apaitane effeting in the parallel HMs setion, the proposed transition has better mathing harateristis than the onventional tapered mirostrip transition in the near ut-off frequeny of the TE 10 mode. Experimental results of the bak-to-bak transition show that the measured insertion loss is within 0.7 to 1.6 db and the 20 db-return-loss bandwidth is from 9.1 GHz to GHz (7.16 GHz). The 15 db-return-loss bandwidth is from 9.02 GHz to GHz (9.11 GHz). Thus, the proposed struture ahieves a good mathing over the omplete fundamental-mode 20 db-return-loss bandwidth (from 1.05 f to 1.9 f ). In onlusion, the proposed transition an improve the return loss harateristis better than the onventional tapered mirostrip transition. The proposed transition an over the omplete fundamental-mode bandwidth. We expet the proposed transition play an important role in the ative iruits and passive omponents based on the. This work was supported by the National Spae Laboratory (NSL) program under the Korea Siene and Engineering Foundation funded by the Ministry of Eduation, Siene and Tehnology ( ). Referenes Fig. 8. Measured S-parameters of the proposed transition and the onventional tapered mirostrip transition. [1] D. Deslandes, K. Wu, "Integrated mirostrip and retangular waveguide in planar form," IEEE Mirowa- 174

5 CHO and LEE : A NEW BROADBAND MICROSTRIP-TO- TRANSITION USING PARALLEL HM ve Wireless Compon. Lett., vol. 11, no. 2, pp , Feb [2] S. Lee, S. Jung, "Ultra-wideband CPW-to-substrate integrated waveguide transition using an elevated- CPW setion," IEEE Mirowave Wireless Compon. Lett., vol. 18, no. 11, pp , Nov [3] N. Jain, N. Kinayman, "A novel mirostrip mode to waveguide mode transformer and its appliations," IEEE MTT-S Int. Mirowave Symp. Dig., vol. 2, pp , [4] T. H. Yang, C. F. Chen, T. Y. Huang, C. L. Wang, and R. B. Wu, "A 60 GHz L TCC transition between mirostrip line and substrate integrated waveguide," Pro. APMC, vol. I, pp. 4-7, De [5] M. Abdolhamidi, A. Enayati, M. Shahabadi, and R. Faraji-Dana, "Wideband single-layer DC-deoupled Substrate Integrated Waveguide ()-to-mirostrip transition using an interdigital onfiguration," Asia- Paifi Mirowave Conferene, De [6] C. -K. Yau, T. -Y. Huang, T. -M. Shen, H. -Y. Chien, and R. -B. Wu, "Design of 30 GHz transition between mirostrip line and substrate integrated waveguide," Asia-Paifi Mirowave Conferene, De [7] D. Deslandes, K. Wu, "Integrated transition of oplanar to retangular waveguides," IEEE MTT-S Int. Mirowave Symp. Dig., pp , May [8] D. Deslandes, K. Wu, "Analysis and design of urrent probe transition from grounded oplanar to substrate integrated retangular waveguides," IEEE Trans. Mirowave Theory & Teh., vol. 53, pp , Aug [9] N. Smith, R. Abhari, "Dispersion-equalization tehniques for substrate integrated waveguide interonnets," IEEE Trans. Mirowave Theory Teh., vol. 58, no. 12, pp , De [10] Q. Lai, C. Fumeaux, W. Hong, and R. Vahldiek, "Charaterization of the propagation properties of the half-mode substrate integrated waveguide," IE- EE Trans. Mirowave. Theory Teh., vol. 57, no. 8, pp , Aug [11] Z. -Y Zhang, K. Wu, "Broadband half-mode substrate integrated waveguide (HM) Wilkinson power divider," IEEE MTT-S Int. Mirowave Symp. Dig., pp , Jun [12] D. Deslandes, "Design equations for tapered mirostrip-to-substrate integrated waveguide transitions," IEEE MTT-S Int. Mirowave Symp. Dig., pp , May Dae-Keun Cho reeived the B.S. and M.S. degree in eletronis engineering from Ajou University, Suwon, Korea, in 2011 and 2013, respetively. His urrent researh interests inlude mirowave and millimeter-wave passive iruit design, iruit and antenna design. Hai-Young Lee reeived the B.S. degree in eletronis engineering from Ajou University, Suwon, Korea, in 1980, the M.S. degree in eletrial engineering from the Korea Advaned Institute of Siene and Tehnology (KAIST), Seoul, Korea, in1982, and the Ph.D. degree in eletrial engineering from The University of Texas at Austin, in 1989.From 1982 to 1986, he was with the Ministry of National Defense, Seoul, Korea, as a senior researh engineer in the fields of eletromagneti ompatibility and wave propagation. From 1990to 1992, he was in harge of the Advaned Researh Division I (Compound Semiondutor Devies Division) at the LG Eletronis Institute of Tehnology, Seoul, Korea. In 1998, he was a Visiting Professor at the University of California at Los Angeles. He served for the President of the Korean Institute of Eletromagneti Engineering and Siene (KIEES) in 2010 and the President of the User Counil at Korea Advaned Nano Fab Center (KANC), Suwon, Korea from 2004 to Sine 1992, he has been with the Department of Eletronis Engineering, Ajou University, Suwon, Korea, as a Professor. His urrent researh interest lies in the fields of mirowave and millimeter-wave iruits design and testing, RF System-On-a-Pakage (SOP), and EMI/ EMC for power and environmental appliations. 175