The purpose of this test method is to verify the shielding efficiency of shielding elements in connection with EMC design of enclosures for electronic equipment and apparatus.
The test method can be used on objects from microscopic items to large cabinets, which may be connected to a cable. The test method makes use of a simple shielded room without absorbing material. In this method the reflections in the room, which are a problem in other test methods, are utilized to simplify the measuring process.
The test method is based on a comparison between the electrical field strengths in a certain position of the test room for two objects, the reference object and the test object. The reference object is an object which is identical with the test object except that it has no electromagnetic shield, i.e. no attenuation.
The position of the reference object and the test object in the test room is arbitrarily chosen, but the position is fixed during the two field strength measurements.