Quadruplet, (Q-factor),. (coaxial cavity resonator) (combline).,,, 198 [5] [11]. (coupling coefficient) (topology) (duplexer) (multiplexer) (Electric

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1 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. 215 Nov.; 26(11), ISSN (Print) ISSN X (Online) Quadruplet Compact Cascaded Quadruplet Bandpass Filter Using Modified Coaxial Cavity Resonator with Q-Factor Improvement 장건호 왕욱광 이보람 박남신 Geon-Ho Jang Xu-Guang Wang Bo-Ram Lee Nam-Shin Park 요약,. Γ %, 35 %., 4.. Abstract This paper presents a novel modified coaxial cavity resonator and its application to bandpass filters with compact size and improved quality factor(q-factor). The proposed resonator is made up of Γ-shape or curved four inner conductive posts within a single cavity, which provides quadruplet to realize bandpass filter. No metallic walls inside the cavity are required, and thus the utilization efficiency of the cavity space is improved. As a result, the unloaded Q can be approximately 15 % higher in comparison to the conventional coaxial resonator, or more than 35 % volume saving can be achieved while maintaining the similar Q-factor value with the conventional designs. In addition, due to the multiple cross-coupling occurring within the cavity, including the source-to-load coupling, four flexible transmission zeros can be created to realize different filtering functions. Simulations as well as experimental results of four- and eight-pole filters are presented to validate this attractive design concept. Good agreement between measured and computed results is obtained. Key words: Coaxial Cavity Resonator, Q-Factor, Bandpass Filter, Miniaturization. 서론,. [1],[2], [3],[4]. ( ) (RF R&D Center, KMW Inc.) Manuscript received July 7, 215 ; Revised November 13, 215 ; Accepted November 19, 215. (ID No S) Corresponding Author: Geon-Ho Jang ( ghjang@kmw.co.kr) 966 c Copyright The Korean Institute of Electromagnetic Engineering and Science. All Rights Reserved.

2 Quadruplet, (Q-factor),. (coaxial cavity resonator) (combline).,,, 198 [5] [11]. (coupling coefficient) (topology) (duplexer) (multiplexer) (Electric or Magnetic coupling) (mixed coupling) [12],[13]., (In-line) (cross-coupling) [14],[15]. SIW(Substrate Integrated Waveguide) 4 (conductive post) (tunable) [16],[17]. 4 (fundamental) 2 (degenerate), (actuator)., 4, (filter order). 4 SCRP(Strongly-Coupled Resonator Pairs) Evanescent [18]. SCRP 4, 3 triplet(ct: Cascaded triplet),. quadruplet(cq: Cascaded quadruplet). 1 (cavity) 4 Γ-,. (coupling window), 15 %., 35 %. 4,,, 4. CST MWS,.. 변형된 Quadruplet 동축공동공진기 1(a)., (tuning screw). (metallic bar). 2-1 공진기의구성및특성 1(b), (c) Γ-. (metallic wall), 9 4 Γ-. d, Γ- h L. 2 g, c (chamfer). 2 d=5.35 mm, B=38 mm, H=16 mm, L=14.2 mm, T=4 mm, h=13.35 mm, W=6 967

3 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 26, no. 11, Nov 한 방향의 자계분포를 가진다. 모드 4는 가장 높은 주파 수(3,772 MHz)로 4개의 포스트가 서로 독립된 자계분포 를 가지며, 마치 도체 벽이 존재하는 일반 동축 공동 공진 기의 배열과 유사하다. (a) (a) Mode 1 (b) (b) Mode 2 (c) 일반 동축 공동 공진기 여파기와 제안된 Γ형 공진기의 (b) 사시도, (c) 상면도 그림 1. (a) (c) Mode 3 Fig. 1. (a) Conventional coaxial cavity resonator and proposed Γ-shape resonator and its (b) perspective and (c) top view. 일 경우, Eigen mode 모 의실험한 결과 전계 자계 분포를 나타낸 것이다. 그림 와 같이 모드 은 가장 낮은 주파수(1,941 MHz)를 가 지며 개 포스트들의 자계분포가 모두 동일한 방향이며 자계 루프를 형성해 하나의 큰 동축 공동 공진기가 존재 하는 것과 같다. 모드 2와 3은 서로 직교된 축퇴모드로 동 일한 주파수(3,36 MHz)를 가지며, 2개의 포스트에 동일 mm, r=3 mm, g=2.5 mm, c=2.8 mm, 1(a), 1,4 968 (d) Mode 4 모의실험 전자계 분포 그림 2. Eigen mode Fig. 2. E-/H-field distributions of the Eigen mode simulation.

4 Quadruplet Resonant frequency(ghz) Unloaded Q-factor Distance d(mm) Mode 1 Mode 2 Mode 3 Mode 4 Average (a) d (a) Resonant frequency when the d varies Distance d(mm) Mode 1 Mode 2 Mode 3 Mode 4 Average (b) d (b) Unloaded Q-factor when the d varies 그림 3. d Fig. 3. Characteristic of the proposed resonator when the distance d varies. d 3,, ( 1) [16],[18]. 3 d 4,., d 4 quadruplet. Γ- 4 pole. 2-2 무부하품질계수 4 (equivalent resonant space).,.. V, A, S (skin depth)., 4 (V) (A)., 1,,.,. 3(b), d,, 4., 1. Eigen mode σ= , 5, GHz 2,867,. 4-pole 23,14 mm 3 ( =1.5 mm)., 4 3, %. 3,381 (1) 969

5 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 26, no. 11, Nov 표 1. Table 1. Comparison of unloaded Q-factor between the conventional and proposed resonators. 그림 4. Fig. 4. Proposed curved type coaxial cavity resonator. 4-pole 3,976(7,744 4) mm 3, 34 %.,,. 4 Γ- 9 y(θ)=d cos(θ), z(θ)=rh sin(θ)., [19]. 3,5 33,856 mm 3, 23,14 mm 3 46 %. Γ-, d r Rh, 4 h1 h4.. 다단 Quadruplet 대역통과여파기의설계 3-1 결합모델, d [16]. (transversal array). d Conventional resonator Proposed Γ-shape resonator Proposed curved type resonator Volume(mm 3 ) 5, mm mm 16 mm 7, mm 22 mm 16 mm 8, mm 23 mm 16 mm 23,14 38 mm 38 mm 16 mm 23,14 38 mm 38 mm 16 mm Resonant mode(mhz) Unloaded Q-factor 2,564 2,867 2,54 3,396 2,561 3,559 Mode 1 : 2,481 Mode 2 : 2,63 Mode 3 : 2,64 Mode 4 : 2,537 Average : 2,556 Mode 1 : 2,422 Mode 2 : 2,679 Mode 3 : 2,682 Mode 4 : 2,528 Average : 2,577 3,13 3,411 3,48 3,63 3,381 3,428 3,78 3,717 3,38 3,576 4, 4 quadruplet. 5 (Fully canonical coupling model) [2].,.,. 97

6 Quadruplet 그림 5. Fig. 5. Fully canonical coupling model. 3-2 결합계수 (direct tapping). 6(a), Ph,., d., d,.. (2) (L) 13.9 mm, 14 mm, 14.1 mm. 6(b), d,. d L,, 1(a) g c,.,, External Q Coupling coefficient k Ph (mm) (a) (a) External quality factor 그림 6. Fig. 6. Coupling coefficient.. L=14.1mm L=14mm L=13.9mm Distance d(mm) (b) (b) Inter-post coupling coefficient 3-3 곡선형공진기를이용한대역통과여파기 7. AA, (coupling iris).,.,,,. 971

7 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 26, no. 11, Nov [7],[21] (+). 2 1, M 14 그림 7. quadruplet Fig. 7. Proposed curved type quadruplet bandpass filter. 표 2. Table 2. The sign of couplings in examples. M S1 M 12 M 23 M 34 M 4L Ex Ex Ex M 13 M 24 M 14 M S4 M 1L M SL Ex Ex Ex Triplet,, [13]. 6 (M S4 = M 1L, M 13 =M 24, M 14, M SL ) 4. ( ). (metallic pin), M S1 =M 4L, M S4 =M 1L, M SL (+). M 12 =M 34, M 23, M 13 =M 24, M 14 M 11 =M 44, M 22 =M 33 (self resonance). 3. 2,6 MHz, 14 MHz, 18 db. S-parameter (db) S-parameters (db) S-parameter (db) Frequency (GHz) (a) Example 1 S11 CM S21 CM S11 EM S21 EM Frequency (MHz) (b) Example 2 S11 CM S21 CM S11 EM S21 EM Frequency (MHz) (c) Example 3 S11 CM S21 CM S11 EM S21 EM 그림 8. 3 Fig. 8. Coupling matrix(cm) and 3D EM simulated response of the designed example filters. 972

8 Quadruplet 표 3. 1 Table 3. Coupling matrix of example 1. S L S L 표 4. 2 Table 4. Coupling matrix of example 2. S L S L S-parameter (db) (a) (a) Asymmetric filer Frequency (GHz) (b) (b) Frequency response S11 S21 표 5. 3 Table 5. Coupling matrix of example 3. S L S L 표 6. Table 5. Coupling matrix of the asymmetric filter. S L S L S21 (db) S21 (db) -1 M 13 = M 13 = M = Frequency (GHz) (c) M 13 S 21 (c) Frequency response when M 13 varies -1 M 24 =.53-2 M 24 =.73-3 M = Frequency (GHz) (d) M 13 S 21 (d) Frequency response when M 13 varies 그림 9. Fig. 9. Proposed asymmetric filter. 973

9 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 26, no. 11, Nov ( ). 3 2, 2 M , 8..,,. 9(a). 1 3, 2 4, M 13 ( ), M 24 (+). 6 3, 9(b), (c). 1 quadruplet. 2,593 MHz, 196 MHz. AA-AA, 7. 8, 4 pole stage 3, 1(b) (coupling bar). 표 7. 8 CQ ( : mm) Table 3. The parameters of proposed CQ filter(unit: mm) Bx By H h 1 h 2 h 3 h Rh d r g 13 g 24 wl cbl cbw cbh ccl ccr cg 1 =cg 2 =cg 3 =cg S-parameter (db) -2-4 (a) quadruplet (a) CQ asymmetric curved type filter -6 S11 w/o coupling bar -8 S11 w/o coupling bar S11 w coupling bar S21 w coupling bar Frequency (MHz) (b) (b) Frequency response 그림 1. quadruplet Fig. 1. CQ asymmetric curved type filter.. 제작및측정결과 11., 3 μm. Agilent VNA E571B. 11(b),.5 db, 2 db., 11(a). 11(c) 974

10 품질계수가 향상된 변형된 동축 공동 공진기를 이용한 다단 Quadruplet 대역통과 여파기 용하여 동일한 성능을 가진 일반 여파기 대비 35 % 이상 의 소형화를 달성할 수 있다. 또한, 조절 가능한 다수의 전송영점을 통해 차단대역의 감쇄특성이 향상되었으며, 그 위치에 따라 다양한 주파수 응답을 가질 수 있음을 보 였다. 본 논문에서 제안한 공진기와 여파기의 설계법은 소형화가 요구되는 무선 이동통신 기지국 시스템에 적용 될 수 있을 것으로 기대된다. 제작된 여파기 (a) (a) Fabrication References S-parameter (db) -2 [1] C. Wang, K. A. Zaki, "Dielectric resonators and filters", -4 IEEE Microw. Mag., vol. 8, no. 5, pp , Oct S11 Simulation S21 Simulation S11 Measurement S21 Measurement [2] S. J. Fiedziuszko, I. C. Hunter, T. Itoh, Y. Kobayashi, T. Nishikawa, S. N. Stitzer, and K. Wakino, "Dielectric ma28 terials, devices, and circuits", IEEE Trans. Microw. Th- Frequency (MHz) 주파수 응답 측정결과 eory Techn., vol. 5, no. 3, pp , Mar. 22. (b) (b) Measured frequency response [3] M. Memarian, R. R. Mansour, "Quad-mode and dualmode dielectric resonator filters", IEEE Trans. Microw. S-parameter (db) -2-4 Theory Techn., vol. 57, no. 12, pp , Dec [4] -6 S11 Conventional S21 Conventional S11 Proposed S21 Proposed Frequency (MHz) 주파수 응답 비교 (c) (c) Comparison of frequency response 제작과 측정 비교과 그림 11. Fig. 11. Test and comparison of fabricated filters. 보이고 있다. 장건호, 박남신, 김병철, 이돈용, 원정희, 왕욱광, "원 통형 삼중모드 유전체 공진기를 이용한 대역 통과 여 파기의 설계", 한국전자파학회논문지 26(1), pp. 3-38, 215년 1월. [5] G. L. Matthaei, "Comb-line band-pass filters of narrow or moderate bandwidth", Microw. J., vol. 6, pp , Aug [6] R. J. Wenzel, "Synthesis of combline and capacitively loaded interdigital bandpass filters of arbitrary bandwidth", IEEE Trans. Microw. Theory Techn., vol. MTT- Ⅴ. 결 19, no. 8, pp , Aug 론 본 논문에서는 새로운 변형된 Γ 또는 곡선형 quadruplet 공진기를 이용하여 4-/8-pole 대역통과 여파기를 설계하였다. 제안된 공진기는 일반동축 공동 공진기보다 15 % 이상의 향상된 품질계수를 가질 수 있으며, 이를 이 [7] R. J. Cameron, C. M. Kudsia, and R. R. Mansour, Microwave Filters for Communication Systems: Fundamentals, Design, and Applications, New York, NY, USA: Wiley, 27. [8] R. R. Mansour, "Filter technologies for wireless base stations", IEEE Microw. Mag., vol. 5, no. 1, pp , 975

11 THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 26, no. 11, Nov Mar. 24. [9] M. El Sabbagh, K. A. Zaki, H. W. Yao, and M. Yu, "Full-wave analysis of coupling between combline resonators and its application to combline filters with canonical configurations", IEEE Trans. Microw. Theory Techn., vol. 49, no. 12, pp , Dec. 21. [1] A. R. Harish, J. S. K. Raj, "A direct method to compute the coupling between nonidentical microwave cavities", IEEE Trans. Microw. Theory Techn., vol. 52, no. 12, pp , Dec. 24. [11] A. Morini, G. Venanzoni, and T. Rozzi, "A new adaptive prototype for the design of side-coupled coaxial filters with close correspondence to the physical structure", IEEE Trans. Microw. Theory Techn., vol. 54, no. 3, pp , Mar. 26. [12] R. J. Cameron, "Advanced filter synthesis", IEEE Microw. Mag., vol. 12, no. 6, pp , Oct [13] J. B. Thomas, "Cross-coupling in coaxial cavity filterstutorial overview", IEEE Trans. Microw. Theory Techn., vol. 51, no. 4, pp , Apr. 23. [14] H. Wang, Q. X. Chu, "An inline coaxial quasi-elliptic filter withn controllable mixed electric and magnetic coupling", IEEETrans. Microw. Theory Techn., vol. 57, no. 3, pp , Mar. 29. [15] Y. Wang, M. Yu, "True inline cross-coupled coaxial cavity filters", IEEE Trans. Microw. Theory Techn., vol. 57, no. 12, pp , Dec 29. [16] E. J. Naglich, J. Lee, H. H. Sigmarsson, D. Peroulis, and W. J. Chappell, "Intersecting parallel-plate waveguide loaded cavities for dual-mode and dual-band filters", IEEE Trans. Microw. Theory Techn., vol. 61, no. 5, pp , May 213. [17],, " ", 21(8), pp , [18] S. Bastioli, R. Snyder, "Evanescent mode filters using strongly-coupled resonator pairs", in IEEE MTT-S Int. Microw. Symp. Dig., 213. [19] Mo Hoft, S. Buerger, "Q-factor improvement of combline resonators", German Microwave Conferenece, UIm, Germany, pp Apr. 25. [2] C. Liao, C. Chang, "Design of microstrip quadruplet filters with source-load coupling", IEEE Trans. Theory Techn., vol. 53, no. 7, pp , Jul. 25. [21] S. Amari, U. Rosenberg, and J. Bornemann, "Adaptive synthesis and design of resonator filters with source/ load-multi resonator coupling", IEEE Trans. Microw. Theory Techn., vol. 5, no. 8, pp , Aug : ( ) : ( ) : ( ) [ 주관심분야 ] RF/,,, Metamaterials 26 8 : Qingdao University ( ) 28 8 : ( ) : ( ) : ( ) [ 주관심분야 ] RF/ / 976

12 Quadruplet : ( ) : ( ) : ( ) [ 주관심분야 ],,, Metamaterials : ( ) : ( ) : ( ) ( ) [ 주관심분야 ] RF/, 977