Problems with stirred immunity measurements in a reverberation chamber: Corrections to DO-160G section 20.6

When DO-160G, Environmental Conditions and Test Procedures for Airborne Equipment [1], Section 20.6, was modified in 2010 to simplify electromagnetic susceptibility measurements in a reverberation chamber and switch from a stepped paddle (mode-stepped or mode-tuned) to a continuously moving paddle (mode-stirred), an error was introduced which overestimates the test level by approximately 1.4 to 3 dB, and possibly more (the error should increase with exposure frequency). We offer a possible explanation for the cause of the error, and suggest several possible ways to give a more accurate estimate of the exposure field.