This part of IEC 62153 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@ the upper frequency is limited by the properties of the baluns. The procedure to measure the coupling attenuation aC is based on the procedure to measure the screening attenuation aS according to IEC 62153-4-5.