羰基铁/三元乙丙橡胶复合材料的吸波性能

Microwave absorption properties of carbonyl iron/EPDM composite

为了探明吸波材料的厚度、吸收剂的含量与吸波性能之间的关系,以羰基铁为吸收剂、三元乙丙橡胶为基体制备了复合橡胶吸波材料,采用矢量网络分析仪研究了在2.6-18 GHz范围内羰基铁含量和吸波材料厚度对吸波性能的影响,并利用电磁理论分析了吸波材料的吸波性能.对于3 mm吸波材料,当羰基铁体积分数为45%时,在3.5 GHz处其反射率的最小值达-21.7 dB;在羰基铁含量一定的条件下,微波吸收性能与吸波材料的厚度并不成正比关系,当厚度〈2 mm时,吸波材料的吸波效果较差;当厚度〉2 mm时,随着吸波材料厚度的增加,最大吸收峰的位置向低频移动,并且最大吸收峰的峰值和指定反射率的频率带宽也呈减小的趋势.在相同厚度下,随着羰基铁含量的增加,吸波材料在电磁波吸收峰处的反射率不断减小,而且吸波材料吸收峰的位置也向低频移动;输入阻抗与空气阻抗越接近,吸波材料的吸波性能越好.

In order to explore the relationships among the thickness of radar absorbing material （ RAM）, the volume content of absorbents in the RAM and the microwave absorption property, the radar absorbing material employed the carbonyl iron powder and ethylene-propylene-diene monomer （EPDM） as its absorbent and matrix was prepared. Effects of carbonyl iron＇ s content and RAM＇ s thickness on its microwave absorption properties in the range of 2.6 - 18 GHz were studied by a vector network analyzer. And the microwave absorption properties were analyzed using the electromagnetic theory. Results showed that the minimum refleetivity of RAM with thickness of 3 mm was -21.7 dB at 3.5 GHz when the carbonyl iron＇ s content was 45%. Microwave absorption properties were not in direct proportion to its thickness when the RAM had the same carbonyl iron＇ s volume fraction. Absorption effect of the radar absorbing material was relatively poor when the thickness was less than 2 mm. With the increase of thickness, the maximum absorption peak moved to low frequency band, its numeric value of maximum absorption peak decreased and the absorption bandwidth of the appointed reflectivity showed to be minished when the thickness was more than 2 mm. With the increase of carbonyl iron＇ s content, reflectivity of the absorption peak for the radar absorbing material continuously decreased and the absorption peak also moved to the low frequency under the same RAM＇ s thickness. And the closer to the air＇ s impedance the input impedance was, the better the microwave absorption property was.