Normalised radio flux density as a function of normalised frequency for our PSR sample, comprising (from top to bottom) 15 objects reported in K17, 25 in J18, 10 in K21, and 13 in S22. Each PSR within the subsamples is colour-coded individually. The solid lines represent the fitted models, with parameters listed in Table A.1, and the black asterisk indicates the characteristic frequency, ν_*. This normalisation process highlights the similar exponential drop-off in the spectra associated with ν_∗ values, arranging PSR spectra in increasing order based on the slope of their emission.