## 2 Methods of Measurement  
According to the current EN IEC 55015:2019-11 standard, the analysis of radiated disturbances generated by lighting technology components is carried out in the frequency range of 9 kHz to 1 GHz. In the frequency band from 9 kHz to 30 MHz, the magnetic field component generated by the test object is analysed while from 30 MHz to 1 GHz, the electric field component is analysed. In addition, if the lamp is powered from the mains power supply in the band from 9 kHz to 30 MHz, the level of conducted disturbances propagated through the power supply circuits of the lamp is measured. According to the provisions of the standard, the measurement of the radio emission of the test object can be carried out on an open OATS (Open Test Area Site) testbed, in a semianechoic chamber SAC, in a fully anechoic chamber FAR, a TEM chamber, or by an indirect method using a coupling and decoupling network referred to in the standard [6] as the 'CDNE method. While the OATS/SAC, FAR, and TEM methods are similar to some extent, the CDNE method does not measure the value of the electric field strength but measures the equivalent value of the induced disturbance voltage at the terminals of the coupling/decoupling network. According to a note in the standard [6], the CDNE method can be used in the frequency range of 30 to 300 MHz alternatively to the previously used methods (SAC, FAR, and TEM). This means that if the lamp under the test obtains a positive result using the CDNE method, it can be concluded on this basis that it meets the requirements of the standard [2] in the frequency range of 30 to 300 MHz. The limitation is that this method can be used for lamps that have components in their circuits that generate clock signals of up to 30 MHz. Modern LED lamps meet this criterion, as the frequencies of the DC/DC and AC/DC converters used in LED lamps range from tens to hundreds of kilohertz. The results obtained for a selected number of LED lamps which were obtained by measuring each lamp first with the SAC method and then with the CDNE method have been compared in this paper. As previously mentioned, the CDNE method was introduced as an alternative method for testing lighting technology objects in the version of the EN 55015 standard issued in 2013. In this method, the level of the disturbance voltage generated in total on all the power supply lines of the object under test is measured during testing at the signal port of the CDN. The measured value of the disturbance signal is expressed in dB\(\mu\)V and is related to the limit curve defined in the standard [6]. The peculiarity of this method is that the measurement can be made in an unshielded room (which means that the measurement does not have to be conducted in an anechoic chamber), provided that during the tests, the level of external disturbance does not affect the measurement result. To confirm this, a disturbance measurement should be carried out before the test in the target configuration with the test object switched off. It is recommended that the level of a disturbance generated by external sources should be at least 6 dB below the permissible value. Another advantage of the CDNE method is that the test duration is considerably shorter than that of the SAC method. In the SAC method, the electrical component of the electric field strength, which is expressed in dB\(\mu\)V/m, is measured. Because the two methods measure different types of disturbance signals, they also have different permissible disturbance limits. The permissible disturbance limits measured by the SAC and CDNE methods are described in Tables 1 and 2. The permissible disturbance levels in Tables 1 and 2 represent a reference limit that cannot be exceeded by the measured values of the analysed disturbances. For both the SAC and CDNE methods, the final disturbance level is determined using a quasipeak detector. The characteristic features by which the two methods differ have been shown in Table 3.  
The main advantage of the CDNE method is the relatively low cost of the test stand.