도전성 섬유를 이용한 전파흡수체에 관한 연구 = A Study on EM Wave Absorbers Using Conductive Cloth

다국어 초록 (Multilingual Abstract)

In this thesis, EM wave absorbers were fabricated with MnZn, NiZn, Ba ferrites, and Sendust on the basis of very thin conductive fibers. The purpose of this research is to develop a complex EM wave absorber with superior EM wave absorption based on conductive fibers.
A conductive fiber which has shield property of 20~40 dB in GHz was used in this work. The absorption ability of EM wave absorber can be increased by using the conductive fibers, because some absorbtion and return losses can be occurred by the conductive fibers. Moreover, the conductive fibers are of light weight, thin thickness, and can be used as binders to fabricate complex EM wave absorbers, therefore it is possible to apply them to the fabrication of EM wave absorber without influencing their weight and volume. Complex EM wave absorbers were made by pasting a sheet of fiber on the backside of existing absorber using epoxy paint which is flexible and not fragile.
In this thesis, two types of fibers, (one is gold-plated with about 0.1Ω/ ㎠ surface resistance, and the other is alumina-plated with 60 Ω/ ㎠ surface resistance), are used, and some EM wave-absorbing materials with high absorption ability, such as MnZn, NiZne, Ba ferrite, and Sendust are used.
As the experimental results, the gold-plated fibers couldn't increase absorption ability but could be used as EM wave shielding materials because of their high shielding efficiency, light weight, and thin thickness (about 0.09 mm).
Comparing the EM wave absorbers composed of the alumina-plated sheet with ones fabricated without the alumina-plated sheet, the former improve the absorption abilities due to the reflection and absorption losses resulted from the alumina-plated sheet itself. Shielding efficiency of alumina-plated sheet is not better than the gold-plated sheet. However, it can be used as EM wave absorbers materials because of its average shielding efficiency of 20 dB to the EM wave absorbers in GHz band, and its thickness is 0.25 mm, weight is light as well as the gold-plated sheet.
Fabricated MnZn ferrite, Ba ferrite, NiZn ferrite, and Sendust EM wave absorbers are useful as a EM wave absorber for S-Band, Ku-Band and C-Bnad, respectively.
This thesis shows that EM wave absorber fabricated with conductive fibers can be a candidate of EM wave absorber with superior EM wave absorption ability for GHz band and do not allow permeation of unwanted EM waves.

목차 (Table of Contents)

• Nomenclatures = ⅴ
• Abstract = ⅵ
• 제 1 장 서론 = 1
• 1.1 연구 배경 및 목적 = 1
• 1.2 연구 내용 및 방법 = 3
• 제 2 장 전파흡수체의 이론 해석 = 4
• 2.1 전송선로 이론에 의한 전자파 흡수해석 = 4
• 2.1.1 평면파의 전자파 = 4
• 2.1.2 분포정수선로 = 8
• 2.1.3 전송선 이론 = 10
• 2.2 1층형 전파흡수체 = 13
• 2.2 2층형 전파흡수체 = 17
• 제 3 장 도전성 섬유의 특성 = 22
• 3.1 도전성 섬유 = 22
• 3.2 도전성 섬유의 전자파흡수원리 = 23
• 3.2.1 전자파차폐 성능 = 23
• 3.2.2 전파흡수에 관한 분석 = 25
• 제 4 장 도전성 섬유를 이용한 전파흡수체의 재료 및 제작 = 29
• 4.1 섬유시트 및 전파흡수 재료 = 29
• 4.1.1 알루미늄 도금 섬유시트의 물리적 특성 = 29
• 4.1.2 금 도금 섬유시트의 물리적 특성 = 31
• 4.1.3 표면비 저항 측정 = 34
• 4.1.4 전기전도도 측정 = 34
• 4.1.5 4단자법에 따른 면저항치의 측정 = 35
• 4.1.6 전자파차폐효율 측정 = 35
• 4.2 전파흡수체 제작 = 35
• 4.2.1 제작된 전파흡수체 구조도 = 36
• 4.2.2 전파흡수체와 에폭시 수지의 혼합비율 = 36
• 제 5 장 도전성 섬유를 이용한 전파흡수체의 측정과 특성 평가 = 37
• 5.1 전파흡수체의 전파흡수체능 측정 및 재료정수 측정 = 37
• 5.1.1 전파흡수체의 전파흡수능 측정 = 37
• 5.1.2 전파흡수체의 재료정수 측정 = 38
• 5.2 알루미늄을 도금한 섬유의 투자율과 유전율 변화 = 40
• 5.3 전파흡수체 두께 변화에 따른 전파흡수능 변화 = 41
• 5.3.1 섬유를 첨가하지 않을 때 두께 변화에 따른 전파흡수능 변화 = 41
• 5.3.2 섬유를 전파흡수체 전자파 투과면에 부착할 때 두께 변화에 = 44
• 5.3.3 섬유를 전파흡수체 중간층에 첨가할 때 전체 두께 변화에 = 48
• 5.3.4 알루미늄 도금섬유의 두께(층수) 변화에 따른 복합전파흡수체의 = 52
• 제 6 장 결론 = 55
• 참고 문헌 = 56