Emission of Electrically Small Radiating Sources from Tests Inside a TEM Cell

Currently there is considerable interest in developing a method to measure the radiated EM emissions and EM susceptibility of electronic equipment. Rectangular coaxial TEM cells developed at NBS for this purpose have been found to be quite satisfactory in establishing standard test field environment for such measurements. One must have a method to obtain the free space radiation characteristics of a test object from measurements taken inside such a cell. To do this we may consider a typical equipment under test (EUT) to consist of an electrically small box housing low frequency AC circuits. The current carrying conductors in each AC circuit may be replaced by equivalent electric/ magnetic dipoles with appropriate phases, and all such dipoles may be combined into a system consisting of three orthogonal electric and three orthogonal magnetic dipoles each excited with arbitrary phase.