A Cavity Filter Tuning System utilizing Coupling Matrix = 커플링 매트릭스를 이용한 캐비티 필터 자동 튜닝 알고리즘

다국어 초록 (Multilingual Abstract)

Manual tuning of RF cavity bandpass filters relies heavily on the empirical skills of expert engineers, leading to issues with low throughput and poor reproducibility. To address these challenges, this thesis presents an automatic tuning system utilizing a coupling-matrix-based linear sensitivity model. The proposed approach defines a target coupling matrix derived from a fully tuned reference filter as a golden sample. By establishing a linear relationship between the physical tuning elements and the coupling coefficients, the system analytically computes the required screw rotations. A systematic tuning algorithm is implemented to automate the process, featuring a hierarchical strategy that prioritizes the alignment of resonators before adjusting inter-resonator couplings to enhance convergence stability. The system integrates a vector network analyzer, a tuning assistant program, and a robotic manipulator within a unified framework. Experimental validation confirms that the proposed system consistently satisfies design specifications with significantly improved tuning efficiency and reproducibility compared to conventional methods. This study demonstrates that the coupling-matrix-based approach provides a robust and scalable solution suitable for mass-production environments. Key word Coupling Matrix, Cavity Filter, VNA, Automatic Tuning, Tuning Algorithm

목차 (Table of Contents)

• Abstract
• Chapter 1. Introduction 1
• Chapter 2. Coupling-Matrix Theory 3
• 2.1. Cavity Filter Model Using the Coupling Matrix 3
• 2.2. Golden-Sample Coupling Matrix of the Sixth-Order Cavity Filter 5
• 2.3. Local Linearity of Coupling Coefficients 8
• Chapter 3. Algorithms 13
• 3.1. Golden-Sample Storage Algorithm 13
• 3.2. Coupling-Matrix Variation Extraction Algorithm 15
• 3.3. Tuning Algorithms 16
• 3.3.1. Manual Tuning Algorithm 16
• 3.3.2. Semi-Automatic Tuning Algorithm 17
• 3.3.3. Automatic Tuning Algorithm 18
• Chapter 4. Experiments 19
• 4.1. Experimental Overview 19
• 4.1.1. Filter Under Test 19
• 4.1.2. Automatic Tuning Program 20
• 4.1.3. Tuning Modes 22
• 4.2. Experiments with BC Mode 24
• 4.3. Experiments with BA Mode 28
• 4.4. Experiments with 7 mm Tuning Screw Height 32
• 4.5. Experiments with 5 mm Tuning Screw Height 36
• 4.6. Improvement of Tuning-Time Efficiency in the Automatic Tuning System 40
• Chapter 5. Conclusion 45
• References 48
• Appendices 51