Investigation of the frequency correlation between radiation patterns of unintentional emitters for large frequency bands

The determination of a radiation pattern for an unintentional emitter is very time-consuming. Therefore, approaches are needed to reduce the costs of such measurements. In previous research, stochastic approaches have been developed to describe the distribution of the directivity and to predict the maximum directivity for continuous wave signals. However, if the radiation pattern needs to be known for a large frequency band, the characteristics of the emitter vary with the frequency. In this paper, the radiation patterns of unintentional emitters are examined for a large frequency band. Based on a simulation model, the similarity of the radiation patterns at different frequencies is determined by calculating the correlation coefficient. It is shown that radiation patterns of close frequencies are correlated up to a correlation distance which is dependent on the electrical size of the emitter.