Additive-manufactured hexagonal waveguide for Ku-band monopulse comparator
- 발행기관 서강대학교 일반대학원
- 지도교수 Jinho Jeong
- 발행년도 2026
- 학위수여년월 2026. 2
- 학위명 석사
- 학과 및 전공 일반대학원 전자공학과
- 실제URI http://www.dcollection.net/handler/sogang/000000082867
- UCI I804:11029-000000082867
- 본문언어 영어
- 저작권 논문은 저작권에 의해 보호받습니다.
초록(요약문)
In this study, a hexagonal waveguide (HWG) structure suitable for high-frequency waveguide implementation is newly proposed using metal additive manufacturing, i.e., a 3D printing process. Since the proposed HWG has a non-standard cross section that differs from conventional rectangular waveguides, its electromagnetic characteristics cannot be directly derived using existing theoretical formulations. Accordingly, the cutoff frequency, single-mode operating bandwidth, propagation constant, and characteristic impedance (𝑍𝑇𝐸10) of the proposed HWG are analyzed in detail. Under identical conditions, these characteristics are compared with those of a standard rectangular waveguide (RWG), specifically the WR-62 RWG, to quantitatively evaluate the impact of cross-sectional geometry on wave propagation behavior. Based on these analytical results, a transition structure was designed to achieve efficient mode conversion and low reflection loss between the RWG and the HWG. Furthermore, a Ku-band Magic-T employing the proposed HWG was fabricated using a 3D printing process to verify the practical applicability of the proposed cross-sectional structure to RF devices. The designed structures were first evaluated through electromagnetic simulations using full-wave analysis tools, and subsequently validated experimentally through measurements using a vector network analyzer. Both simulation and measurement results indicate that the proposed transition structure achieves excellent impedance matching and power transmission characteristics, exhibiting a reflection loss greater than 24 dB and an insertion loss below 0.1 dB over the Ku-band operating range. In the case of the HWG-based Magic-T, a reflection loss greater than 15 dB, an insertion loss below 0.31 dB, an isolation exceeding 43 dB between output ports, and an isolation exceeding 20 dB between input ports were obtained. These results confirm that the proposed HWG, along with the associated transition structure and Magic-T, can be effectively utilized as a feeding network for 3D- printed waveguide modules. In addition, a monopulse comparator employing the proposed HWG-based Magic-T as a core building block was designed, and its performance was evaluated through electromagnetic simulations. Within the operating bandwidth, the comparator achieved a reflection loss greater than 14.7 dB and an isolation exceeding 38.6 dB, demonstrating that the proposed Magic-T and HWG configuration can be effectively applied to monopulse comparator implementations.
more목차
Abstract vii
1. Introduction 1
2. Dual polarization monopulse comparator with CNC milling 5
2.1 Dual-polarized monopulse comparator Block diagram 5
2.2 Fabrication and limits 7
3. Hexagonal waveguide: Structure and electromagnetic characteristics 10
3.1 RF components fabricated by 3D printing 10
3.2 3D printing techniques and design guideline 13
3.3 Surface roughness modeling and Hall Huray simulation 17
3.4 Hexagonal waveguide 21
3.5 Electromagnetic characteristics of hexagonal waveguide 22
3.6 Cross-polarization characteristics of hexagonal waveguide 29
3.7 Bandwidth comparison with WR-62 waveguide 31
3.8 Impedance matching Iris in the hexagonal waveguide 33
4. Magic-T: Design and implementation 42
4.1 Hexagonal waveguide magic-T 42
4.2 Hexagonal waveguide to WR-62 waveguide transition 50
4.3 Prototype verification using FDM 3D printing 53
4.4 Measurement 57
4.5 Comparison 64
5. Monopulse comparator: Design 67
5.1 Reverse type magic-T 67
5.2 Hexagonal waveguide monopulse comparator 72
5.3 Simulation result 75
6. Conclusion 77
Reference 79
