本計畫研究以鎳銅鋅鐵氧體(Ni0.5-0.5xCuxZn0.5-0.5x)Fe2O4為電磁吸波材料主體，當與Epoxy結合為複合材料試片，且假設在背面貼附有金屬板的條件下，探討如何進一步提昇其吸波能力及降低反射損失的方法，其中包含改變鐵氧體中銅莫耳比例x、合成煆燒溫度，另外摻雜CNF藉以增加介電損失，在頻率2~18 GHz之間量測複合材料試片的磁損和介電損耗能力，在以5 GHz為中心頻率的應用條件下，探討可以得到最低反射損失的最佳製作參數與試片厚度範圍。在鎳銅鋅鐵氧體吸波能力實驗中，結果顯示設定較高的銅莫耳比例與煆燒溫度，其粉體會有較高的測量密度，而只有於2~8 GHz之間會有較高的導磁係數虛部，表示鎳銅鋅鐵氧體在低頻範圍才具有較佳的磁損能力，而其介電損耗在全頻段均偏低。當只有摻雜鎳銅鋅鐵氧體至Epoxy製成試片，如粉體煆燒溫度為1000℃，x = 0.3，試片厚度為6.1mm時，計算出來的反射損失為-22.2dB，-20dB頻寬為1.36GHz。其次增加CNF，製成(Ni0.35Cu0.3Zn0.35)Fe2O4/CNF/ Epoxy試片，實驗結果顯示可以在10 GHz以上提昇介電損耗能力，且隨著CNF的摻雜量增加而增加；在整體試片於5 GHz應用上，計算結果顯示，當CNF摻雜量為0.5 wt%，試片厚度為5.3mm時，反射損失降低為-25.7dB，而-20dB頻寬略增為1.4GHz，因此少量摻雜CNF可以使試片在較薄的厚度下獲得改善的反射損失，但增加CNF摻雜量可以使試片厚度更薄，但有提高反射損失的缺點。

This research uses NiCuZn ferrite (Ni0.5-0.5xCuxZn0.5-0.5x) Fe2O4 as the main electromagnetic absorbing material, when combined with Epoxy to form a composite test piece. It is assumed that there is a metal attached to the back of the absorbing material, exploring how to improve its absorbing ability and reduce reflection loss. The method includes changing the Cu mole ratio x in the NiCuZn ferrite, the sintering temperature, and doping CNF to increase the dielectric loss.
In the experiment of the absorbing ability of NiCuZn ferrite, the results show that setting a higher Cu mole ratio and sintering temperature will result in a higher measurement density of the powder. When the NiCuZn ferrite/Epoxy test piece is only doped NiCuZn ferrite, and the powder sintering temperature is 1000℃, x = 0.3, the thickness of the test piece is 6.1mm, the calculated reflection loss is -22.2dB, and the -20dB bandwidth is 1.36GHz. Additionally, CNF is added to make (Ni0.35Cu0.3Zn0.35)Fe2O4/CNF/Epoxy test piece. The calculation results demonstrate that when the CNF doping amount is 0.5 wt% and the thickness of the test piece is 5.3mm, the reflection loss is reduced to -25.7dB, and the -20dB bandwidth is slightly increased to 1.4GHz. Therefore, a small amount of doping CNF can improve the reflection loss of the test piece at a thinner thickness and increasing the amount of CNF doping can make the thickness of the test piece thinner.

[1] V. Tarateeraseth, K. Y. See, F. G. Canavero, and R. W.-Y. Chang, "Systematic electromagnetic interference filter design based on information from in-circuit impedance measurements," IEEE Trans. Electromagn. Compat., vol. 52, no. 3, pp. 588-598, 2010.
[2] 李宗哲, "金屬複合奈米粒子於電磁波吸收之研究," 博士論文, 化學工程學系, 國立成功大學, 2007.
[3] A. R. Bueno, M. L. Gregori, and M. C. Nóbrega, "Microwave-absorbing properties of Ni0. 50–xZn0. 50− xMe2xFe2O4 (Me= Cu, Mn, Mg) ferrite–wax composite in X-band frequencies," J. Magn. Magn. Mater., vol. 320, no. 6, pp. 864-870, 2008.
[4] B. Quan et al., "A permittivity regulating strategy to achieve high-performance electromagnetic wave absorbers with compatibility of impedance matching and energy conservation," New J. Chem., vol. 41, no. 3, pp. 1259-1266, 2017.
[5] X. Zhou et al., "Microwave sintering carbon nanotube/Ni0. 5Zn0. 5Fe2O4 composites and their electromagnetic performance," J. Eur. Ceram. Soc., vol. 33, no. 11, pp. 2119-2126, 2013.
[6] F. Nanni, P. Travaglia, and M. Valentini, "Effect of carbon nanofibres dispersion on the microwave absorbing properties of CNF/epoxy composites," Compos. Sci. Technol., vol. 69, no. 3-4, pp. 485-490, 2009.
[7] Y. Kotsuka, Electromagnetic Wave Absorbers: Detailed Theories and Applications. John Wiley & Sons, 2019.
[8] M. P. Reddy et al., "Effect of sintering temperature on structural and magnetic properties of NiCuZn and MgCuZn ferrites," J. Magn. Magn. Mater., vol. 322, no. 19, pp. 2819-2823, 2010.
[9] Y. Hwang, "Microwave absorbing properties of NiZn-ferrite synthesized from waste iron oxide catalyst," Mater. Lett., vol. 60, no. 27, pp. 3277-3280, 2006.
[10] K.-Y. Park, J.-H. Han, S.-B. Lee, J.-B. Kim, J.-W. Yi, and S.-K. Lee, "Fabrication and electromagnetic characteristics of microwave absorbers containing carbon nanofibers and NiFe particles," Compos. Sci. Technol., vol. 69, no. 7-8, pp. 1271-1278, 2009.
[11] R. Dosoudil, M. Ušáková, J. Franek, J. Sláma, and V. Olah, "RF electromagnetic wave absorbing properties of ferrite polymer composite materials," J. Magn. Magn. Mater., vol. 304, no. 2, pp. e755-e757, 2006.
[12] Z. Fan, G. Luo, Z. Zhang, L. Zhou, and F. Wei, "Electromagnetic and microwave absorbing properties of multi-walled carbon nanotubes/polymer composites," Mater. Sci. Eng., B, vol. 132, no. 1-2, pp. 85-89, 2006.
[13] S.-Y. Tong et al., "Design and characteristics of flexible radio-wave absorber consisted of functional NiCuZn ferrite–polymer composites," J. Alloys Compd., vol. 509, no. 5, pp. 2263-2268, 2011.
[14] D.-L. Zhao, Q. Lv, and Z.-M. Shen, "Fabrication and microwave absorbing properties of Ni–Zn spinel ferrites," J. Alloys Compd., vol. 480, no. 2, pp. 634-638, 2009.
[15] 林福昌 and 李化, 电磁兼容原理及应用. 机械工业出版社, 2009.
[16] 楊繼深, 電磁相容技術之產品研發與認證. 全華圖書股份有限公司, 2014.
[17] J. Fan, X. Zhao, X. Gao, and C. Cao, "Electric field regulating behaviour of microwave propagation in ER fluids," Journal of Physics D: Applied Physics, vol. 35, no. 1, p. 88, 2001.
[18] M. Meshram, N. K. Agrawal, B. Sinha, and P. Misra, "Characterization of M-type barium hexagonal ferrite-based wide band microwave absorber," J. Magn. Magn. Mater., vol. 271, no. 2-3, pp. 207-214, 2004.
[19] T. Maeda, S. Sugimoto, T. Kagotani, N. Tezuka, and K. Inomata, "Effect of the soft/hard exchange interaction on natural resonance frequency and electromagnetic wave absorption of the rare earth–iron–boron compounds," J. Magn. Magn. Mater., vol. 281, no. 2-3, pp. 195-205, 2004.
[20] X. Huang, J. Zhang, M. Lai, and T. Sang, "Preparation and microwave absorption mechanisms of the NiZn ferrite nanofibers," J. Alloys Compd., vol. 627, pp. 367-373, 2015.
[21] A. Nicolson and G. Ross, "Measurement of the intrinsic properties of materials by time-domain techniques," IEEE Transactions on instrumentation and measurement, vol. 19, no. 4, pp. 377-382, 1970.
[22] P. Niknejad. "Scattering Parameters." University of California, Berkeley. https://pdf4pro.com/view/eecs-242-1f4176.html.
[23] W. B. Weir, "Automatic measurement of complex dielectric constant and permeability at microwave frequencies," Proceedings of the IEEE, vol. 62, no. 1, pp. 33-36, 1974.
[24] C.-H. Peng, H.-W. Wang, S.-W. Kan, M.-Z. Shen, Y.-M. Wei, and S.-Y. Chen, "Microwave absorbing materials using Ag–NiZn ferrite core–shell nanopowders as fillers," J. Magn. Magn. Mater., vol. 284, pp. 113-119, 2004.
[25] C.-H. Peng, C.-C. Hwang, J. Wan, J.-S. Tsai, and S.-Y. Chen, "Microwave-absorbing characteristics for the composites of thermal-plastic polyurethane (TPU)-bonded NiZn-ferrites prepared by combustion synthesis method," Mater. Sci. Eng., B, vol. 117, no. 1, pp. 27-36, 2005.
[26] H. Su, H. Zhang, X. Tang, and X. Xiang, "High-permeability and high-Curie temperature NiCuZn ferrite," J. Magn. Magn. Mater., vol. 283, no. 2-3, pp. 157-163, 2004.
[27] 林國寶, "鎳鋅鐵氧體粉體電磁特性和粒徑分佈對石墨烯/Epoxy 複合吸波材料之影響," 碩士論文, 電機工程學系, 國立成功大學, 台南, 2020.
[28] G. G. Tibbetts, M. L. Lake, K. L. Strong, and B. P. Rice, "A review of the fabrication and properties of vapor-grown carbon nanofiber/polymer composites," Compos. Sci. Technol., vol. 67, no. 7-8, pp. 1709-1718, 2007.
[29] M. Jaroszewski, S. Thomas, and A. V. Rane, Advanced Materials for Electromagnetic Shielding: Fundamentals, Properties, and Applications. John Wiley & Sons, Inc, 2018.
[30] P. Journal of Applied PhysicsKarimi, M. Ostoja-Starzewski, and I. Jasiuk, "Experimental and computational study of shielding effectiveness of polycarbonate carbon nanocomposites," J. Appl. Phys., vol. 120, no. 14, p. 145103, 2016.
[31] S. Sugimoto et al., "M-type ferrite composite as a microwave absorber with wide bandwidth in the GHz range," IEEE Trans. Magn, vol. 35, no. 5, pp. 3154-3156, 1999.