Look-up plot with which to estimate the average value of B_⊥ along a LOS, ⟨B_⊥⟩, for a given frequency ν and brightness temperature spectral index β assuming the CRe spectrum by Orlando (2018). Black and white isocontours show specific values of ⟨B_⊥⟩ with labels in μG. Yellow symbols indicate estimates of ⟨B_⊥⟩ obtained from the values of in the frequency ranges 115−189 MHz, 467−672 MHz, and 833−1200 MHz (labelled as , , and , respectively)at a common resolution of 6.7′ for the different POSs of the two simulation snapshots (circles: POS yz in the strongfield case; squares: POS yz in the weak field case; diamonds: POS xy and zx in the weak field case; triangles: POS xy and zx in the strong field case). Rectangles at the bottom of the plot show the frequency ranges of the low and high band antenna of LOFAR (LBA and HBA, respectively), the low and mid frequency bands of SKA (SKA1-Low and SKA1-Mid, respectively), and SKA pathfinders and precursors: the Hydrogen Epoch of Reionisation Array (HERA); the Murchison Widefield Array (MWA); the Karoo Array Telescope (MeerKAT); and the Australian SKA Pathfinder (ASKAP).