A Comparative Study on Spatial Uniformity Metrics for Reverberation Chambers

Reverberation chambers are well-known for their time-efficient and flexible testing functionality. Spatial uniformity is a key characteristic of the chamber influencing measurement uncertainty. Depending on the target parameter and application, the conventional uniformity assessment method may not fully capture the effects within the chamber. Thus, the capability of the enhanced backscattering constant and the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$K$</tex>-gamma factor to assess uniformity is investigated at millimeter-wave frequencies. Using the standard deviation of power transfer function as a reference and demonstrating its correlation with other parameters shows that the enhanced backscattering constant could be applied for uniformity assessments. Moreover, the practical importance of each parameter in its relevant application is highlighted, leading to effective methods for assessing uniformity and validating chambers for Over-the-Air tests. Given its high sensitivity to chamber configuration and antenna positioning, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$K$</tex>-gamma factor can complement the conventional power transfer function method, delivering additional insights and practical improvements in measurement setups.