You've not really provided much information, but an EMC test is looking for vulnerabilities of the victim circuit relative to radiated susceptibility, so the source needs to have an antenna to properly radiate its EM signal against the victim.
This site is not for tutorials; I would suggest using Wikipedia and other internet resources for that.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!
The test equipment connects a Wide frequency Signal Generator, Amplifier, antenna, sends energy through the airwaves ... energy arrives at victim. This Energy moves electrons at the victims equipment and causes the victims equipment to malfunction.
Usually, victim needs to shield the equipment.
Most equipment is an accidental antenna, with poor antenna efficiency.
Most people never realize the equipment leaks energy out or can leak in side their equipment.
In a properly sealed set of electronics, the equipment is a very very inefficient antenna.
The purpose of the EMC tests is to find out where equipment is acting like an antenna, then seal that area (usually using metal shielding), then redo the EMC tests until the level of energy received does not affect the equipment. Two type tests;
1) How much energy leaks out of your equipment (you run your equipment, and use an external antenna to measure the amount of energy that leaks out of your antenna).
2) How much energy when sent into the equipment bothers it (they put a calibrated amount of energy into your equipment from a calibrated antenna at a distance of 1 meter or 3 meters, then have that antenna move around (to represent real life where the offending antenna can be oriented in many directions) and see if your equipment malfunctions when running certain tests.
