Scintillation bandwidth versus the observing frequency in log-log scale. Filled symbols designate our LOFAR measurements presented in this paper, and open symbols are previously published values collated from literature and given (with references) in the table in Appendix A. The black dashed lines with a slope of α show the best fit to the Δv_d values across our LOFAR observing band. The gray dashed line corresponds to the Kolmogorov spectrum with α = 4.4, which is only plotted in case the best-fit line is inconsistent with the Kolmogorov spectrum.