Coherence-Distance Estimation of Non-Linear Mode-Stirring Mechanisms

One of the main sources of uncertainty when measuring antenna characteristics in a reverberation chamber is correlation. Current methods of determining correlation between mode-stirring positions, such as autocorrelation, are constant over absolute stirrer positions. This work shows that the coherence distance can vary over position using the Pearson-correlation method to determine the coherence distance of mode stirring mechanisms. From this, it will be shown that the autocorrelation method underestimates the actual coherence distance. Using this method, stirring sequences can be optimized, and thus antenna measurements inside a reverberation chamber can be improved.