Interference Aggregation Involving Near- to Far-Field Propagation of Disturbance and its Impact on Emission Limits for Radio Protection

To introduce the interference aggregation effect into the emission-limit-setting model, aggregate interference power arising from randomly distributed disturbance sources is studied considering the near- to far-field propagation of radiated disturbance. It is assumed that point sources are uniformly distributed in a two-dimensional model and that the distance to the victim receiver ranges from the near-field region to the far-field region. A piecewise approximation is applied to the distance attenuation curve with a corner distance that indicates the border between the near and far fields. The mean value, standard deviation, and probability density function (PDF) of the decibel-scaled aggregate interference power are theoretically and numerically analyzed at various source densities. The results show that the shape of the PDF markedly changes as the source density increases because of the mixed contribution of disturbing sources both from the near and far fields. Accordingly, the variations in the mean value and standard deviation of the aggregate interference power are strongly dependent on the distance attenuation at which major interfering sources are found. When introducing the interference aggregation effect into the emission requirements, both the distance attenuation characteristics and the estimated source density in a real environment should be carefully considered.