A SIMPLIFIED RELATIONSHIP BETWEEN SURFACE TRANSFER IMPEDANCE AND MODE STIRRED CHAMBER SHIELDING EFFECTIVENESS OF CABLES AND CONNECTORS

.The relationship between surface transfer impedance and stirred mode chamber shielding effectiveness proposed by Eicher and Boillot has been simplified. This simplified relationship was used to compare the measured stirred mode chamber shielding effectiveness of nine shielding artifacts with the shielding effectiveness of the same samples calculated from transfer impedance measurements made at lower frequencies or obtained by calculation. For samples with colocated apertures, the relationship predicted the mode stirred shielding effectiveness reasonably well. When the apertures were distributed over a finite length, the relationship predicted mode stirred shielding effectiveness’ that were 7 to 10 dB less than those that were measured. This suggests that different relationships must be used for single or colocated apertures and distributed apertures. Above 7 to 10 GHz, the measured stirred mode shielding effectiveness decreases faster than 20 dB/decade. This is probably due to circumferential resonances or resonances within the cable. .