EMI Testing：A Comprehensive Guide to Evaluating EMI Test Receiver Performance

In recent years, the issue of Electromagnetic Interference (EMI) has gained more and more attention. There are two forms of EMI, namely conducted interference and radiated interference. Conducted interference refers to the signal from one electrical network being coupled (interfered) into another electrical network through conductive medium. Radiated interference refers to a signal in one system being coupled (interfered) into another electrical network or electronic device by space. As such, high speed PCB systems design, high frequency signal wires, IC pins, connectors, etc., all can be radiation interference sources which have antenna characteristics and thus affect the normal performance of others systems or devices.

EMI testing is a test that is used to detect the strength of the radiated interference produced by the equipment under test (EUT/ DUT). It is constituted by two parts: RE testing and CE testing. RE testing is used to detect the radiations energy of the EUT whilst CE testing is used to measure the response of the EUT to external signals.

EMI (Electromagnetic Interference) refers to the phenomena that signals in one system or electronic device are unintentionally coupled into another system or electronic device via space or conductive medium, and this received signal will affect the performance of the interfered system. In the lighting industry, EMI testing not only meets the certification standards of different countries, but has also become a necessary test for lighting equipment. For EMI interference testing equipment, a three-loop antenna and an EMI test receiver are generally used internationally. The three-loop antenna is mainly used to convert the low-frequency magnetic-field components in the X, Y, and Z axes into radio-frequency signals, which are then transmitted via a co-axial cable wire to the EMI receiver and finally analyzed and processed by software to detect the interference level.

In addition, within the frequency range of 9KHz-300MHz, CDN (Coupling Decoupling Network) is also used in EMI testing, whereby RF signals are isolated for sampling and impedance matching, and power is provided for testing devices. CDN terminal voltage method is mainly based on CISPR-15 standard to test the interference signals generated by lamps and lighting devices, and the final conclusion is provided by the analysis and limit of EMI test software. This approach covers the frequency range from 9KHz-300MHz and addresses the emerging LED lighting industry. For the LED lighting industry, a scan frequency of 30MHz to 300MHz is specifically required in CE certification, and thus CDN is more accurate and effective when it comes to improving the safety and reliability of lighting devices.

The test of electronic appliance quality also applies to lighting devices. Take, for instance, FCC certification in the US and CE certification in the EU which both require LED lighting devices to comply with EMI interference test items. Conducted interference test frequencies are from 0.15MHz to 30MHz while radiated interference test is from 30MHz to 1GHz; for CE certification, conducted interference test frequencies are from 9KHz to 30MHz and radiated interference test is from 30KHz to 300MHz. For EMI testing from 9KHz to 30MHz, antenna, EMI test receivers, and CISPR15, EN55015, GB17743 standards can be utilized; for the low-frequency magnetic field that may be produced by lighting apparatuses, three-loop antenna measurement for radiated interference can be based on CISPR116-1-4; and another approach is the LISN testing method which is an internationally accepted testing method composed of EMI checker, man-made power grid, LISN and test software. For EMI testing from 9KHz to 300MHz, CDN is used, which involves an EMI test receiver, CDN and attenuators making up a testing system to test the conducted interference generated by lamps and lighting devices under normal operation.

EMI has a great impact on our society, and thus it should be avoided for electromagnetic radiation pollution and is accurately defined as an endeavor for better electromagnetic compatibility enhancement. The International Organization CISPR (COMITÉ INTERNATIONAL SPECIALIRADIO INTRUSION) has defined a number of electromagnetic compatibility standards to make sure that the secure use of electronic and electrical systems in our society is ensured. In Europe, the European Standard Committee (ESC) issued standards such as EN55015 and EN55022 that standardize the electromagnetic compatibility restrictions and other requirements of single electronic products to reduce the social issues due to electromagnetic interference.

Therefore, EMI control and management, be it for governmental agencies, scientific teams or electronic/electrical manufactures, should be taken responsibly to eliminate electromagnetic pollution, and a full understanding of CISRP-16 standards and its related requirements, reasonable design and assembly of products, optimization of product structures, and use of corresponding testing methods and EMI testing equipment should be achieved to elevate the electromagnetic interference performance of products, ensuring the steadiness of the social order and maintaining a healthy social environment.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

Our main products are Goniophotometer, Integrating Sphere, Spectroradiometer, Surge Generator, ESD Simulator Guns, EMI Receiver, EMC Test Equipment, Electrical Safety Tester, Environmental Chamber, Temperature Chamber, Climate Chamber, Thermal Chamber, Salt Spray Test, Dust Test Chamber, Waterproof Test, RoHS Test (EDXRF), Glow Wire Test and Needle Flame Test.

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