Comparison of anechoic and reverberation chamber coupling data as a function of directivity pattern

Abstract

This paper extends previous work on comparing data from anechoic and reverberation chamber tests. Since the test electromagnetic environment in the two techniques are different, one-to-one comparisons of equipment responses are difficult. Responses in both anechoic and reverberation tests depend on equipment directivity but in different ways. The expected results also have different dependencies on variations in test conditions (e.g., the number of aspect angles in an anechoic chamber test and the number of samples/tuner positions in a reverberation chamber test). However, as shown in the previous work, results from typical tests in both chambers yield comparable error biases. The error bias is defined as the ratio of a measured response for specific test conditions to the true maximum response. The paper compares the expected error bias and uncertainty in the coupling as a function of the apparent directivity for both test techniques. The apparent directivity (both magnitude and pattern) of equipment responses is derived from measured anechoic chamber data. Measured error biases and uncertainties are presented for typical anechoic chamber tests (four aspect angles, two polarizations) and typical reverberation chamber tests (12 tuner positions) for specified field equivalency conditions. This work extends the Part I analysis by including data from two additional instrumented test articles. The analysis utilizes an extensive data base from both anechoic and reverberation chamber tests. These tests measured the transfer function from an external field to an internal probe at a fixed location over the frequency range 0.5 to 18 GHz in both anechoic and reverberation chambers.