電磁波吸收材質之研究

The Development of Electromagnetic-Wave Absorption Materials

賴元泰(Yuan-Tai Lai)

指導教授 ： 王宏文

中原大學/理學院/化學研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200297

摘要

摘要
為了使陶瓷粉末能獲得較佳的均勻程度，本研究不同於一般傳統的氧化物混合法，而以化學檸檬酸法（溶膠-凝膠）製備含有摻雜物的錳鋅鐵氧磁體。 實驗大致上分為兩部分，第一部份是以 Fe , Mn , Zn ,之硝酸鹽為起始原料，使用檸檬酸來螯合所需成分之硝酸鹽水溶液中的金屬離子，再於適當的溫度下濃縮、去水進行酯化反應而獲得所需金屬離子之酯化先驅物，之後經由適當的熱處理、鍛燒後即得到所需成分之金屬氧化物粉體。之後並取依條件相同的粉體以不同的方式合成，比較其差異性。 第二部分乃將第一部份所得之粉體與熱塑性的PU（thermalplastic polyurethane）做充分的混合之後，以模具壓製成外徑為7mm , 內徑為3mm之同心圓試片，以配合網路向量儀（HP 8753ES）之量測 ( transmission line 為 coxial)。
研究以錳鋅鐵氧磁體材料為主，開發低頻之單層高導磁性、高損失鐵氧磁體吸波材料，藉由摻雜不同的金屬，及陶瓷粉末與TPU不同的混合比例，改善其四個特性參數（介電常數實部、虛部，導磁率實部、虛部）進而改變其電磁波吸收之頻段與頻寬。
並利用四個特性參數以理論( effective medium theory incorporating the invariant the Debye-Hertz potential)計算出反射損失，在改變試片厚度的情況下電磁波吸收程度之增減與頻段之改善。

關鍵字

電磁波 ； 吸收

並列摘要

Abstract
The complex permeability and permittivity of ferrite and polymer composite materials used for the electromagnetic-wave absorbers play a key role in determining the reflection or attenuation properties of the incident microwave. The complex permeability and permittivity a was investigated for ferrite-TPU composite with ferrite weight percentage varying from 66.7%-88.9%, and the ferrite doped with metal (Cr,Bi,Mg,Co,Cu )has been prepared by citrate gel route.
The complex permeability and permittivity were measured using a network analyzer HP 8753-ES. The effective complex permeability and permittivity specta in composites with various ferrite weight percentage and different dopant were calculated using the Bruggeman effective medium theory. It was found that the dopant content and ferrite-TPU ratio influences the microwave-absorbing characteristics of MnZn ferrite composite. The results show that a microwave absorber with reflection loss of about 20dB can be designed by controlling the ferrite fraction in ferrite-TPU composites and different metal doped for the frequency below 3 GHz.

Keywords : Microwave-absorbing, MnZn ferrite, composites, permittivity ε, permeability μ, reflection loss

並列關鍵字

Electromagnetic-Wave ； absorber

參考文獻

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