Radiated emissions measurements are performed in a variety of measurement environments, the international standard being the Open-Area Test-Site (OATS). Differences between measurements made on differing OATS's can be accounted for by examining the behaviour of equipments-under-test (EUT's) considered as assemblies of elemental dipoles [1]. GTEM Cells are also commonly used and a number of workers have proposed techniques for converting measurements made in GTEM Cells to their OATS equivalents [2]. These techniques also assume that the equipment-under-test can be represented as a set of orthogonal radiating elemental dipoles. The fields that would be radiated on an OATS are computed from measurements made in the GTEM cell on this basis. In each case two effects are unaccounted for. The first is that the current conversion algorithms assume that the individual dipoles of the EUT are all in phase; this is unlikely to be the case with all but the simplest EUT structures. The second is cross-polar coupling between the EUT dipoles and the measurement antenna on the OATS; an equivalent effect also occurs in the GTEM cell. These two effects combine to increase the uncertainty in the measurement conversion process.
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