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Novel resonant structures for microwave filter applications

Novel resonant structures for microwave filter applications

신임섭 申林燮
서명 / 저자사항
Novel resonant structures for microwave filter applications / Imseob Shin
Seoul :   Graduate School, Korea University,   2016  
xiv, 81장 : 삽화, 도표 ; 26 cm
기타형태 저록
Novel Resonant Structures for Microwave Filter Applications   (DCOLL211009)000000066057  
學位論文(博士)-- 高麗大學校 大學院 : 컴퓨터·電波通信工學科, 2016. 2
0510   6YD36   300  
지도교수: 金英植  
참고문헌: 장 75-81
이용가능한 다른형태자료
PDF 파일로도 이용가능;   Requires PDF file reader(application/pdf)  
DGS , resonator , filter,,
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040 ▼a 211009 ▼c 211009 ▼d 211009
085 0 ▼a 0510 ▼2 KDCP
090 ▼a 0510 ▼b 6YD36 ▼c 300
100 1 ▼a 신임섭 ▼g 申林燮
245 1 0 ▼a Novel resonant structures for microwave filter applications / ▼d Imseob Shin
260 ▼a Seoul : ▼b Graduate School, Korea University, ▼c 2016
300 ▼a xiv, 81장 : ▼b 삽화, 도표 ; ▼c 26 cm
500 ▼a 지도교수: 金英植
502 1 ▼a 學位論文(博士)-- ▼b 高麗大學校 大學院 : ▼c 컴퓨터·電波通信工學科, ▼d 2016. 2
504 ▼a 참고문헌: 장 75-81
530 ▼a PDF 파일로도 이용가능; ▼c Requires PDF file reader(application/pdf)
653 ▼a DGS ▼a resonator ▼a filter
776 0 ▼t Novel Resonant Structures for Microwave Filter Applications ▼w (DCOLL211009)000000066057
900 1 0 ▼a Shin, Im-seob, ▼e
900 1 0 ▼a 김영식 ▼g 金英植, ▼e 지도교수
900 1 0 ▼a Kim, Young-sik, ▼e 지도교수
945 ▼a KLPA


No. 원문명 서비스
Novel resonant structures for microwave filter applications (35회 열람)
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No. 소장처 청구기호 등록번호 도서상태 반납예정일 예약 서비스
No. 1 소장처 과학도서관/학위논문서고/ 청구기호 0510 6YD36 300 등록번호 123053075 도서상태 대출가능 반납예정일 예약 서비스 B M



In this dissertation, a few novel resonant structures based on the defected ground structure (DGS) have been presented, and their applicability to microwave filter has been theoretically and experimentally verified through simulation, fabrication and experiment. Resonators/filters have played important roles in a wide variety of RF/microwave applications. Emerging and challenging applications such as the latest radars and wireless communications demand new RF/microwave resonators/filters meeting much more stringent requirements - higher performance, smaller size, lighter weight, easier fabrication, and so on. Therefore, there have been many efforts to invent, apply and improve many new resonant concepts and components in order to overcome such difficult requirements, and the forbidden bandgap (FBG) structures such as electromagnetic bandgap (EBG) structures and DGSs are one of the results of the numerous challenges and attempts. However, the FBG structures also have the intrinsic drawbacks and difficulties of application. Due to too many parameters that should be considered, a main disadvantage of the EBG structures is the difficulty in its modeling, which gives rise to the emergence of the DGS. Although the DGS consists of one single unit cell and is easier to model than the EBG structure, it also needs the help of the EM simulator for the quantitative design. Thus, in spite of a few design parameters, the DGS configuration that can be easily controlled is preferred. In addition, due to the inherent limitations derived from the ground etching, the DGS specially suffers from the low quality factor and back-radiation loss.
In summary, this work is the result of efforts to surmount these drawbacks of the conventional DGS and to devise the simple and compact resonators with higher performance as follows.
Firstly, the resonant ground structure (RGS) based on a cavity-backed DGS is presented. The substrate-filled metallic cavity (SFMC) which covers a ground-defected pattern can improve the quality factor significantly and remove the back-radiation without increasing the size. The RGSs with dumbbell-shaped and spiral-shaped defects are fabricated, measured and compared with the DGSs having the same defects respectively. The quality factor of the RGS with a spiral-shaped defect is larger than that of the DGS with the same defect by a factor of 7.4. It may be expected that the RGS has several times higher quality factor than the conventional DGS depending on the defect shape. In other words, the low quality factor and back radiation of the existing DGSs can be easily surmounted through the concept of the RGS/SFMC. Moreover, the simple design method for the compact triple-band resonator has been validated using three different resonators: defected microstrip structure (DMS), split-ring resonator (SRR), and RGS.
Secondly, the modified spiral-shaped DGS (MS-DGS) is described in detail. The conventional spiral-shaped DGS (CS-DGS) is one of the representative DGSs with the highest quality factor. The MS-DGS is made by symmetrically dividing the CS-DGS into two pieces and forming a middle lane. Therefore, the current is coupled to the ground-defected pattern at the resonant frequencies and it flows along the middle lane at the non-resonant frequencies without coupling. On the contrary, the current at all frequencies in the CS-DGS flows along the ground-defected pattern because the transversely formed defect directly impedes the current flow. As a result, in spite of the same defect size, the MS-DGS has higher quality factor than the CS-DGS by a factor of 6.04. Moreover, in case of the asymmetric MS-DGS, two asymmetric defects divided by the middle lane generate a dual-band resonance which features a similar bandwidth and high quality factor.
Thirdly, the optimum bandstop filter (BSF) using the DGS-embedded stub is presented. The proposed DGS-embedded stub resonator consists of the shunt open-circuited stub and the embedded dumbbell-shaped DGS, which is placed at the stub-connected point in a T-junction. In the frequency range where the harmonic stopband is generated by the stub, the embedded DGS prevents the current from being coupled to the stub. Therefore, the current does not recognize the stub and just flows along the main line. On the other hand, in the low frequency range, the slow-wave effect of the embedded DGS reduces the stub length. Therefore, compared with the optimum BSF using the conventional stubs, the optimum BSF using the DGS-embedded stubs has about the 50 % upper passband extension and about the 15.0 % size reduction. It is noteworthy that the DGS embedded in the stub resonator can remove the harmonic stopband, while the DGS has been conventionally used to suppress undesirable or unwanted passbands so far.
Fourthly, the compact resonant slit structure (RSS) for the rectangular waveguide BSF is presented. Though the EBG structure for the rectangular waveguide has been presented, the DGS is not feasible in the rectangular waveguide which features the non-grounded structure. However, the newly introduced RSS has many comparable characteristics as well as configuration which is reminiscent of the dumbbell-shaped DGS, and thus can be modeled as a series branch of parallel RLC resonant circuit. Depending on how to install the RSS, various responses such as narrow-band, wide-band, and dual-band can be achievable. In addition, the RSS does not have the drawbacks of the DGS such as low quality factor and back-radiation loss. Owing to the compact RSS, it is possible to implement a much smaller BSF compared with the conventional BSF based on a shunt branch series-resonant circuit. The compact rectangular waveguide BSF using the RSS is designed, fabricated and measured by the equivalent circuit-based design method.
To conclude, the research work presented here is a theoretical and experimental study on the new resonant structures based on the DGS, which could impart much flexibility in the design of future RF/microwave resonator/filter applications.


1. Introduction 1
 1.1 Overview of Defected Ground Structure 2
 1.2 Motivation and Organization of the Dissertation 7
2. Resonant Ground Structure Based on a Cavity-Backed DGS 9
 2.1 Preview 9
 2.2 Modeling and Structure Parameters 11
  2.2.1 Modeling and Equivalent Circuit 11
  2.2.2 Structure Parameters 14
 2.3 Measured Results and Discussion 17
 2.4 Compact Triple-Band Resonator using RGS 19
2.5 Concluding Remarks 24
3. Modified Spiral-Shaped DGS with Improved Performance 26
 3.1 Preview 26
 3.2	Characteristics of MS-DGS 27
 3.3	Parameter Study 30
 3.4	Asymmetric MS-DGS with Dual-Band Property 35
 3.5	Filter Design and Measurement 39
 3.6	Concluding Remarks 42
4. DGS-Embedded Stub Resonator and Its Application to Optimum BSF 43
 4.1	Preview 43
 4.2	DGS-Embedded Stub Resonator 44
 4.3	Optimum BSF with Extended Upper Passband 47
 4.4	Concluding Remarks 51
5. Resonant Ground Structure for a Rectangular Waveguide and Its Application to BSF 52
 5.1	Preview 52
 5.2	Single-Sided Resonant Slit Structure 54
  5.2.1 Configuration & Equivalent Circuit Model of SS-RSS 54
  5.2.2 Parameter Study 58
 5.3	Double-Sided Resonant Slit Structure 62
 5.4	Bandstop Filter Implementation 67
 5.5	Concluding Remarks 71
6. Conclusions 73

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