Research on a guideline of stirrer installation in reverberation chamber

This paper presents a guideline for determining an adequate position and orientation of a stirrer. A stirrer is used to improve a uniform electric field on a working volume inside a reverberation chamber (RC). An efficient stirrer is expected to change boundary conditions and field characteristics such as magnitude and direction, so as to improve the uniform electric field. To determine an adequate installation location of a stirrer, we have analyzed efficiency of two kinds of stirrers with different shapes, and measured field uniformities. Efficiency of each stirrer has been investigated in terms of the number of independent samples that the stirrers can provide, and E field strengths and powers in the working volume measured in order to investigate the field uniformity. Measurement results show that the field uniformity and the stirrer efficiency are deteriorated by STD 0.8 dB and 20% point, respectively, when the stirrer is located less than λLUF/4 close to any chamber wall and in a parallel orientation with the wall. Hence, it is recommended that a stirrer should be installed in a position > λLUF for the field uniformity and < 2λLUF for a large working volume, and in an orientation to avoid a parallel angle with the ceiling or any wall.