Radiated Immunity

Most electronic equipment is, in some manner, affected by electromagtic radiation. This radiation is frequently generated by such sources as cellular phones, the small hand-held radio transceivers that are ued by operating, mainenance and security personnel, fixed-station radio and television transmitters, vehicle radio transmitters, and various industrial electromagnetic sources.

The simulation and measurement of electromagnetic radiation is not adequately exact for quantitative determination of its effects on electronic equipment. That is why it is necessary to perform immunity testing on this kind of equipment. During these tests the equipment is setup in a proper manner and is switched on. All sides must be exposed to the electromagnetic radiation and the performance in all possible states must be checked during testing. This makes the test time-consuming and accurate work.

The electromagnetic environment is determined by the strength of the electromagnetic field (field strength in volts per metre). The field strength is not easily measured without sophisticated instrumentation nor is it easily calculated by classical equations and formulae because of the effect of surrounding structures or the proximity of other equipment that will distort and/or reflect the electromagnetic waves. At the electrophysics laboratories of BICON Labs radiated susceptibility tests can be performed up to 40GHz and field strength levels in access of 200V/m.

When performing the tests it is required that the EUT and possible auxiliary equipment are exercising all normal modes of operation. The test results may be classified on the basis of the operating conditions and functional specifications of the EUT, according to the following performance criteria:

• (A) Normal performance within the specification limits;
• (B) Temporary degradation or loss of function or performance which is self-recoverable;
• (C) Temporary degradation or loss of function or performance which requires operator intervention or system reset;
• (D) Temporary degradation or loss of function or performance which is not recoverable, due to damage of equipment (components) or software, or loss of data.