Effects of Increasing Number of Disturbance Sources on the Setting of Emission Limits

The effects of increasing the number of electromagnetic disturbance sources on the emission limits for radio protection are studied from two different viewpoints: with and without considering the aggregation of disturbance from multiple sources. It is assumed in a 2-D model that sources are randomly located following a uniform distribution, except for the area within a protection distance from a victim receiver, and that disturbance is attenuated by independent statistical factors. Limit values are estimated at various source densities by using probability distributions of the received disturbance power. The results indicate that limits derived by the conventional method tend to underestimate the interference risk as the source density increases even if the aggregation effect is not considered. To reduce the risk, the limits should be estimated on the basis of the strongest disturbance, which is not necessarily from the nearest source. The reduction of protection distance is also worth considering. When the aggregation is taken into account, the difference between the probability distribution of disturbance power from the nearest source and the total disturbance power should be carefully estimated when setting limits, particularly in the case of a high source density and a low propagation loss.