Conducted radio frequency (RF) immunity refers to an electronic or electrical systems ability to function while receiving RF stress in the environment that the systems will function. There are a variety of methods and standards that prescribe how and when testing for this is done. The four main methods of testing are, direct injection, coupling decoupling networks (CDNs), electromagnetic (EM) clamps, and bulk current injection (BCI) probes. CDNs are often the preferred method given its easily reproducible and limits external factors. Below you will find a breakout of common conducted RF standards and associated frequencies.
Test Methods
Below you will find a diagram explaining all three of the major types of current injection methods. Keep in mind the below diagrams are using the Teseq NSG 4070 platform with associated accessories. Individual generators and setups can vary depending upon compliance to selected standards.
RF systems, which include a combination of required components, often used in this conducted immunity standard. The systems include several key components for testing to IEC 61000-4-6 often including amplifier, power meter, signal generator, dual directional coupler, sensors and screen interface usually accompanied by software. The NSG 4070 comes in several different wattage variations including 110 watt, 80 watt, and 60 watt with associated power meters and signal generator built in. Given the different test levels and evaluation of testing environment, often times external amplifiers can be used in place of the built in the amplifier. (additional dual directional coupler and associated equipment required). The below picture are the most common systems made by Teseq and EM Test.
CDN
The preferred method of testing for this standard is coupler decouple networks (CDNs). This is because it fits it is easily reproducible and offers protection of the AE. There is also a given contingency that if the CDNs are not available on the market, then other injection methods maybe used. There are seven different variations depending upon the type of cable being used, CDN-S1, CDN-M1/-M2/-M3, CDN-AF2, CDN-T2, CDN-T4, CDN-AF8, and CDN-T8. These are presented in diagrams 6.2.2.2, 6.2.2.4, 6.2.2.3, and 6.2.2.5.
EM Clamps
Another common method for testing conducted RF immunity is the electromagnetic (EM) clamp. For this standard it specifies operating frequencies from .15MHz-80MHz however, often times they cover up to 1GHz for added testing capabilities. These are ideal as they allow for a variety of different types of cable and are readily available on the market, both for purchases and rentals. Below you will find two common EM Clamps that can be used with a variety of systems. The EM101 clamp also includes a decoupling clamp that can be used to help protect the remaining equipment connected to the EUT.