CDNE is a type of coupling decoupling network used for an alternative technique to measure radiated emission from lighting equipment in accordance with the CISPR 15 (EN55015) standard.
It avoids the need for emission measurements at open test sites. This method was established in CISPR 15 Edition 9 as an acceptable alternative to a traditional OATS test configuration which required antennas and calibrated test sites. It is specified for the frequency range from 30 MHz to 300 MHz. The CDNE method and the associated limits up to 300 MHz can only be applied to EUTs with clock frequencies below or equal to 30 MHz. In such a case, the product is considered to meet the requirements between 300 MHz and 1000 MHz.
Compared to CDNs, CDNEs are considerably more stringently specified, with reduced common mode (CM) impedance tolerance and additional parameters for CM phase tolerance and differential mode impedance equal to 100 Ω. At least 20 dB for longitudinal conversion loss shall prevent symmetrical voltage affecting measurement results.
CISPR 15 edition 9 also specifies that the mains cable to the EUT must be terminated with a CDNE located on the reference ground plane for the measurement method OATS, SAC or FAR.
Unlike CDNs, CDNEs are not suitable for immunity measurements
Tekbox TBCDNE-M2 is designed for EUTs that do not have a PE (earth) connection. Tekbox offers the TBCDNE-M3 model for measuring EUTs with PE, neutral and line connections.