声学散射体对混波室独立采样点的影响

Influence of Acoustic Diffuser on Reverberation Chamber Independent Sampling Points

为研究散射体对独立采样的影响,已提出了一种利用基于声学理论的Schroeder散射体来增加低频时的独立采样点数的方法,以改善混波室在低频时的性能。通过时域有限差分(FDTD)数值仿真与实验相结合,给出了不同频率散射体加入到装有搅拌器的混波室的前后采样点功率密度的相关系数以及相应的独立采样点;分析了数值仿真与实验的结果,给出了加入散射体前后天线校准因子(ACF)随频率的变化关系。结果证明散射体能有效增加混波室在低频时的独立采样点数,为改善混波室的低频性能提供了思路。

In order to improve the performance of the reverberation chamber in relative lower frequency, a type of Schroeder diffuser based on the acoustic theory is designed and used. The correlation function of power density distribution and independent sampling points of the diffusers added to the reverberation equipped stirrers or not are measured and numerical simulated using finite-difference time-domain （FDTD） method for different frequency, respectively. The antenna calibration factor （ACF） of the reverberation chamber is tested, and is compared to the ACF of the reverberation chamber which installed diffuser to the same one which has no diffuser. The results of measurement and numerical simulation prove that the diffuser improves the number of independent sampling points at lower frequency,and the loss of the reverberation chamber is bigger which is installed with the diffuser especially at the high frequency. The Schroeder diffuser based on acoustic theory is proved to be an effective way to improve the performance of the reverberation chamber in low frequency and extend the lowest used frequency （LUF） of the reverberation chamber.