GB/T 39278-2020Method for measuring the shielding effectiveness of shielding enclosures having all dimensions between 0.1 m and 2 m (English PDF)

National Standard of the People's Republic of China

ICS

33.100.10

Classification

L 06

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

Contents

• 1 Scope1
• 2 Normative references1
• 3 Terms and definitions1
• 4 Preparation before measurement2
• 4:1 Background2
• 4:2 Test Plan2
• 4:3 Equipment calibration2
• 4:4 Reference level2
• 4:5 Dynamic range2
• 4:6 Personnel in the shielded enclosure3
• 4:7 Initial test of shielding effectiveness3
• 4:8 Determination of measurement results3
• 5 Measurement method selection3
• 6 Measurement method of shielding effectiveness of 0:75m~2m shielding shell4
• 6:1 Recommended measurement frequency4
• 6:2 Calculation of measurement results4
• 6:3 Preparation for measurement5
• 6:4 9kHz~30MHz frequency band measurement5
• 6:5 Measurement in frequency band above 30MHz9
• 7 Measuring method of shielding effectiveness of small physical size (< 0:75m) and electrically large shielding shell14
• 7:1 Overview14
• 7:2 Measuring equipment15
• 7:3 Confirmation of mixing chamber15
• 7:4 Measuring frequency15
• 7:5 Measuring principle of frequency stirring15
• 7:6 Selection criteria for frequency stirring bandwidth15
• 7:7 The receiving antenna in the tested shielded shell16
• 7:8 Antennas in the external mixing chamber16
• 7:9 Measuring arrangement16
• 7:10 Calculation of shielding effectiveness17
• 7:11 Calculation of the average value18
• 7:12 Calibration of coaxial cable19
• 8 Measurement uncertainty19
• 9 Test report19
• Appendix A (informative appendix) Initial test and improvement21
• Appendix C (informative appendix) Electrically small-sized shielded enclosure in mixing chamber29
• Appendix E (Normative Appendix) Internal Radiation Law36
• Appendix F (informative appendix) Other relevant information40
• Appendix G (Normative Appendix) Shielding Effectiveness Calculation Formula of 0:75m~2m Shielding Shell42
• Appendix H (Informative Appendix) Shielding Effectiveness Measurement Basis of 0:75m~2m Shielding Shell44
• Appendix I (informative appendix) Working principle of monopole antenna mounted on the wall48
• Appendix J (Normative Appendix) Impedance Mismatch Correction53
• Appendix K (informative appendix) Isolated monopole antennas used in external mixing chambers56