I have considered three simple distributions. They are an increasing triangle, a rectangular distribution, and a decreasing triangle, denoted as models 1, 2, and 3 respectively. All the models are normalized to have rms field strength equal to unity.
The probability distributions of the field strength B are then
Figure 8. Colour-colour diagrams for the simple field distribution models, for D=0.1, for the set of frequencies (6, 20, 91) cm.
The parallel section of the colour-colour locus moves closer to the diagonal line as the probability distribution is biased toward lower fields. This is also true for the Gaussian field models - the probability distribution (equation 2) of an n-dimensional random field B has a factor B^n-1 which skews the distribution to higher fields in the higher dimensional cases. This dependence of the shape of the colour-colour plot on the magnetic field model is therefore a potentially useful tool for studying the magnetic field distribution in radio sources.