加载物吸收截面和材料介电常数对混响室品质因子的影响

Influences of Absorption Cross Section of Loading Objects and Material Permittivity on Quality Factor in Reverberation Chamber

为实现混响室(RC)品质因子Q的科学评估、研究混响室腔体加载物对Q的影响,分析了腔室内能量的耗散途径。将加载物等效为一系列能够吸收反射电磁能量的球形介质,通过计算介质球吸收截面,给出了Q的表达式,并建立混响室模型对Q进行数值计算。研究了Q与加载物材料、尺寸的关系。结果表明,当频率>1.2 GHz时,Q的计算结果与实际测量结果相符;Q与加载物吸收截面成反比,与加载物介电常数及入射电磁波频率成正比。

In order to estimate the quality factor（Q） properly and to investigate the influence of loading objects of reverberation chamber（RC） on Q, we analyzed the way of energy dissipation in RC. The loading objects can be regarded as a series of spherical media which absorb and reflect electromagnetic energy. After calculating the absorption cross-section of a spherical medium, we deduced a formula of Q and built a RC model to calculate Q. In addition, we analyzed the relationship between Q and the material and size of the loading object. The results show that the calculated Q is in accordance with the measured result when the frequency is higher than 1.2 GHz. Q is proportional to the permittivity of loading objects and the frequency of the incident electromagnetic wave, and it is inversely proportional to the absorption cross-section of the loading objects.