EMC, also known as electromagnetic Interference (EMI) has become a major issue in many applications. By definition, the equipment has to be designed such that

  1. The generation of electromagnetic interference is limited to such an extend that the proper operation of this equipment is not affected,
  2. The equipment has to have a reasonable resistance against electromagnetic interference so that the proper operation is not affected.

To satisfy these requirements, equipment manufacturers must use connectors with sufficient shielding properties.  This applies also to the connecting cables. Connectors must have conductive housings (metal) to which the cable shield can be terminated. In case of cylindrical connectors, the cable shield must be carefully connected to the connector to provide a 360° shielding. Generally, good shielding performance is achieved when the braided shielding of the cable is firmly connected to the conductive connector housing. Plastic connectors without metal sleeves have no possibility to terminate to the cable shield. In addition, it is important that the mated connector pair has a secure galvanic connection between the plug and receptacle housing.  It is also necessary that the panel-mounted receptacle has a good galvanic connection between the metal receptacle housing and the metal panel surface. The shielding attenuation is measured in decibel (dB) and is frequency-dependent. Good shielding provides a high attenuation values over a large frequency range (MHz).

Attenuation (dB) vs. Frequency (MHz) curve for Series 423 connectors