Method of shielding effectiveness analysis for an enclosure with an aperture

Analytical expression for the coupling coefficient of an aperture with an enclosure is obtained. This expression permits to realize a fast evaluation of shielding effectiveness by an enclosure with an aperture. Method of shielding effectiveness analysis of communications electronics equipment is developed. Its novelty is the use of an electromagnetic approach and of approach based on the obtained expression. Using the obtained expression the shielding effectiveness in location of the observation point at the beginning and middle of the SNP 339 connector enclosure is calculated in the frequency range from 10 kHz to 1 GHz. Coincidence of frequency dependencies obtained using known analytical and numerical methods with the proposed expression is shown. A study is given for a metal enclosure when there is a metallic object in its aperture without an electrical connection to the enclosure and when there is a dielectric with dielectric permittivity of high value.