This standard specifies the measurement and calculation methods for the shielding effectiveness of electromagnetic shielding rooms with dimensions not less than 2.0m on each side. The test frequency range is 9kHz~18GHz. According to needs, the frequency can be extended to 50Hz and 100GHz to both ends. If the shielding room is used in a fully anechoic room or a semi-anechoic room, the shielding effectiveness test should be carried out before the absorbing material is installed.