ANALYSIS AND REALIZATION OF LOW-COST DAMPED SCREENED ROOMS

Radiated emission measurements in rooms suffer the excitation of room resonances, problems in measurement repeatability and difficulties in correlating emission measurements in a screened room to those on an op en area test site occur as a result. One possible solution to this pro blem is by damping the room through the inclusion of small amounts of absorber. The effect of introducing resistive sheets in a screened roo m is examined using numerical modelling and experimental measurements, Results from the numerical model and the experimental measurements sh ow that significant broadband damping may be achieved. The numerical m odel considered the frequency range of 30-500 MHz and comparison of th e response in the room with the predicted free-space response shows th at a screened room error of +/-5dB may be achieved over a broad freque ncy range. Experimental measurements were carried out on a screened ro om for the frequency range of 30-200 MHz and these show a reduction in variations in field levels from +/-30dB down to +/-5dB.