IEC 62153-4-9:20 18+A1:2020适用于金属通信电缆。它规定了确定屏蔽平衡电缆耦合衰减aC的测试方法。由于同心外管，测量与圆周上的不规则性和外部电磁场无关。宽动态和频率范围可用于使用正常仪器测试超屏蔽电缆，从低频到外部电路中定义的横波极限（约4 GHz）。然而，当使用巴伦时，上限频率受到巴伦特性的限制。可以根据IEC 62153-4-4使用标准试管程序（分别使用标准测试头）或使用开放试管（开放测试头）程序进行测量。 本文描述的测量耦合衰减aC的过程基于根据IEC 62153-4-4.这第二版取消并取代了2008年出版的第一版。本版构成技术修订版。与上一版相比，此版本包括以下重大技术变更: -两种测试程序，开放头部和标准头部程序； -分别用巴伦或多端口混合模式VNA进行测量； -频率范围扩展至2GHz及以上。 该合并版本由第二版（2018年）及其修正案1（2020年）组成。因此，除本出版物外，无需下令修订。

IEC 62153-4-9:2018+A1:2020 applies to metallic communication cables. It specifies a test method for determining the coupling attenuation aC of screened balanced cables. Due to the concentric outer tube, measurements are independent of irregularities on the circumference and external electromagnetic fields. A wide dynamic and frequency range can be applied to test even super screened cables with normal instrumentation from low frequencies up to the limit of defined transversal waves in the outer circuit at approximately 4 GHz. However, when using a balun, the upper frequency is limited by the properties of the balun. Measurements can be performed with standard tube procedure (respectively with standard test head) according to IEC 62153-4-4 or with open tube (open test head) procedure.
The procedure described herein to measure the coupling attenuation aC is based on the procedure to measure the screening attenuation aS according to IEC 62153-4-4. This second edition cancels and replaces the first edition published in 2008. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
– two test procedures, open head and standard head procedure;
– measuring with balun or with multiport respectively mixed mode VNA;
– extension of frequency range up to and above 2 GHz.
This consolidated version consists of the second edition (2018) and its amendment 1 (2020). Therefore, no need to order amendment in addition to this publication.