Broadband and compact Ku-band orthomode transducer and monopulse comparator design
- 주제어 (키워드) Waveguide , orthomode transducer , monopulse comparator
- 발행기관 서강대학교 일반대학원
- 지도교수 정진호
- 발행년도 2025
- 학위수여년월 2025. 2
- 학위명 석사
- 학과 및 전공 일반대학원 전자공학과
- 실제 URI http://www.dcollection.net/handler/sogang/000000079812
- UCI I804:11029-000000079812
- 본문언어 영어
- 저작권 서강대학교 논문은 저작권 보호를 받습니다.
초록 (요약문)
This paper proposes a compact Ku-band orthomode transducer (OMT) and monopulse comparator, both realized using waveguide structures. The designed OMT utilizes a plus-shaped waveguide (P-WG) structure to achieve miniaturization and effective separation of vertical and horizontal polarization fields. The P-WG, with an impedance characteristic intermediate to the input square waveguide (S-WG) and the output rectangular waveguide (R-WG), enables broadband impedance matching through a single iris, eliminating the need for a multi-step impedance transformer. Additionally, the implementation of small-square waveguides (SS-WGs) suppresses in-band spurious resonances, further enhancing the bandwidth. Measurements of the fabricated OMT demonstrate superior performance, achieving a return loss greater than 10 dB from 13.5 to 17.5 GHz for vertical polarization and from 13.6 to 16.7 GHz for horizontal polarization, insertion loss below 0.8 dB, isolation exceeding 46 dB, and cross-polarization higher than 41 dB. The proposed monopulse comparator is designed based on a magic-T structure. The magic-T employs a two-step rectangular prism and iris structure for impedance matching, ensuring ease of fabrication and achieving excellent amplitude and phase imbalance performance. The fabricated magic-T achieves a return loss of over 15 dB from 13.9 to 15.6 GHz, with an insertion loss of less than 0.3 dB, amplitude/phase imbalance below 0.05 dB/0.5°, and isolation exceeding 45 dB. The monopulse comparator is constructed by symmetrically connecting four magic-Ts. Chamfered structures are applied to the H- plane bends to reduce reflections. The final fabricated monopulse comparator achieves a return loss greater than 13 dB across 14.1 to 16.1 GHz, with insertion loss below 0.5 dB, amplitude/phase imbalance less than 0.11 dB/1.7°, and isolation exceeding 50 dB, demonstrating superior isolation and amplitude/phase imbalance performance compared to existing designs.
more목차
1. Introduction 1
2. Ku-band orthomode transducer 5
2.1 Design of Ku-band orthomode transducer 5
2.2 Fabrication and measurement of Ku-band orthomode transducer 14
3. Ku-band monopulse comparator 24
3.1 Design of Ku-band magic-T 24
3.2 Fabrication and measurement of Ku-band magic-T 27
3.3 Design of Ku-band monopulse comparator 34
3.4 Fabrication and measurement of Ku-band monopulse comparator 36
4. Conclusion 47
Reference 48