ANALYSIS OF SHIELDED-ROOM ERROR FOR SCREENED ROOMS AND ITS APPLICATION TO LOW-FREQUENCY EMISSION MEASUREMENTS FROM ELECTRICALLY SMALL SOURCES

Screened rooms are an alternative to open area test sites for radiativ e emission measurements. The cost of screened anechoic rooms by compar ison is considerable, especially for low-frequency operation. The pape r considers the use of screened rooms operated below resonance in obta ining low-frequency emission measurements from electrically-small sour ces. The screened room is modelled as a lossless rectangular cavity us ing a rapidly convergent Green's function formulation. This is used to establish the shielded-room error for electric and magnetic current s ources and examine the main coupling mechanisms between the source and observation point in a screened room. Emission measurements are prese nted for a self-contained electrically-small test source. Comparison w ith open-air measurements and emission measurements from a TEM cell sh ow agreement to within +/- 5dB.