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High-Power Water-Cooled RF Load

고출력 마이크로파 수냉식 RF Load 설계

  • Heo, Ye-Rim (Department of Electronic Convergence Engineering, Kwangwoon University) ;
  • Lee, Cheol-Eon (Department of Electronic Convergence Engineering, Kwangwoon University) ;
  • Park, Su-Yeon (Department of Electronic Convergence Engineering, Kwangwoon University) ;
  • Kang, Ju-Yeong (Department of Electronic Convergence Engineering, Kwangwoon University) ;
  • Choi, Jin Joo (Department of Electronic Convergence Engineering, Kwangwoon University)
  • 허예림 (광운대학교 전자융합공학과) ;
  • 이철언 (광운대학교 전자융합공학과) ;
  • 박수연 (광운대학교 전자융합공학과) ;
  • ;
  • 최진주 (광운대학교 전자융합공학과)
  • Received : 2019.05.24
  • Accepted : 2019.06.20
  • Published : 2019.06.30

Abstract

This paper presents the design of a water-cooled radio-frequency(RF) load with simple structure, for use in the ultrahigh-frequency (UHF) band. After establishing a formula to obtain the physical properties that affect RF matching, we measure the permittivity and $tan{\delta}$(Loss tangent) of tap water. Because the temperature of tap water increases upon applying high power, we measure the permittivity and $tan{\delta}$ for all changes in the temperature of tap water. In order to reduce the length of the water-load, molybdate with high $tan{\delta}$ is mixed with tap water. The loss tangent of the mixture is found to be approximately 26 times higher than that of tap water. Finally, we manufacture a water-cooled RF load and measure its characteristics. A reflection coefficient of -19 dB and bandwidth of 15 % is obtained at 460 MHz.

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그림 2. 수돗물의 온도에 따른 유전율과 tanδ Fig. 2. Permittivity and loss tangent of changed tap water temperature.

JJPHCH_2019_v30n6_445_f0002.png 이미지

그림 3. Molybdate 농도에 따른 혼합물의 유전율과 Fig. 3. Permittivity and loss tangent of changed molybdate’s concentration.

JJPHCH_2019_v30n6_445_f0003.png 이미지

그림 4. 혼합물의 온도에 따른 유전율과 tanδ Fig. 4. Permittivity and tanδ of changed molybdate mixture temperature.

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그림 5. Water-load의 초기 디자인 모델 Fig. 5. Early design of water-load.

JJPHCH_2019_v30n6_445_f0005.png 이미지

그림 6. 초창기 모델의 시뮬레이션 결과 Fig. 6. Simulation results of early design.

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그림 7. Water-cooled RF load의 CAD 도면 Fig. 7. CAD layout of water-cooled RF load.

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그림 8. 오링의 유무에 따른 water-load의 S11 Fig. 8. S11 of water-load with/without O-ring.

JJPHCH_2019_v30n6_445_f0008.png 이미지

그림 9. 실제 제작된 수냉식 RF load Fig. 9. Manufactured water-cooled RF load.

JJPHCH_2019_v30n6_445_f0009.png 이미지

그림 10. 제작된 수냉식 RF load의 S11 Fig. 10. S11 of manufactured water-cooled RF load.

JJPHCH_2019_v30n6_445_f0010.png 이미지

그림 11. Transformer 길이 변화에 따른 수냉식 RF load의 반사계수 특성 Fig. 11. S11 of water-load based on change of length of transformer.

JJPHCH_2019_v30n6_445_f0011.png 이미지

그림 12. 혼합물과 수돗물을 넣었을 때의 특성 비교 그래프 Fig. 12. Comparison of the characteristics of a mixture and tap water.

JJPHCH_2019_v30n6_445_f0012.png 이미지

그림 1. (a) 측정 배치도, (b) 등가 회로 Fig. 1. (a) The layout of probe measurement, (b) equivalent circuit.

표 1. 4개의 기준 물질 및 물질의 유전율 Table 1. 4 reference materials and permittivity.

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표 2. Gauss Seidel 기법을 이용하여 구한 미지수 값 Table 2. Coefficients obtained from Gauss Seidel technique.

JJPHCH_2019_v30n6_445_t0002.png 이미지

Acknowledgement

Supported by : U.S Office of Naval Research, 광운대학교

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