Anechoic chamber performance characterization using Spherical Near-Field Imaging techniques

Characterizing the electromagnetic performance of anechoic chambers, particularly large anechoic chambers, can be complex and time consuming. Two measurement techniques commonly used for chamber characterization include free space VSWR and quiet zone probing. The data produced by these chamber evaluation techniques is generally not sufficient to fully characterize the entire chamber. This paper presents a characterization technique utilizing spherical near-field imaging which provides data sufficient to determine the level and direction of signals reflected from all anechoic chamber surfaces and fixtures which enter the quiet zone, and to determine the extraneous signal level within a specified quiet zone volume. The basis of the measurement technique is described and typical chamber test results are discussed.