EMI Prediction of Multiple Radiators

A new method is developed to predict the scaling of the electromagnetic interference from a large system if similar subsystems are added. The method gives the predicted emission from multiple radiators as well as the level of certainty of the estimation. The proposed statistical approach is based on the phased array antenna theory and Monte Carlo simulation for a router with several line cards ( N ) and optical modules inserted. To validate the method, a large router with 498 optical modules with an unwanted radiation at 10.31 GHz was investigated in two different cases: the same frequency and different frequency per radiating subsystem. Several statistical experiments were performed for the proposed problem. The effect of phase and amplitude variations over the radiators is reported in this paper. The method is useful when it is not practical to assemble extraordinary amounts of identical hardware in a product installation. The results indicate the existence of a 10 log N (dB) tendency for the maximum electric field emission in a system radiating at the same frequency with random phase distribution over the radiators. For different frequency subsystems, the slope of the maximum electric field emission is lower than the 10 log N (dB) formula.