Distribution of rest-frame 1.4 GHz luminosity of the Radio Sources Sample (blue circles) and the Radio-excess AGN Sample (orange diamonds) with redshift for the GOODS-N (top) and COSMOS/UltraVISTA (bottom) fields. The 5σ detection limit for the COSMOS/UltraVISTA field with σ = 2.3 μJy beam⁻¹ at 3 GHz (Smolčić et al. 2017b) is shown as a gray dashed line in the top panel and as a black solid line in the bottom panel. The 5σ detection limit for the GOODS-N field with σ = 2.2 μJy at 1.4 GHz (Owen 2018) is shown as a black solid line in the top panel and as a gray dashed line in the bottom panel. All the detection limits are calculated by Eq. (1) assuming a fixed spectral index of −0.8 (see details in Sect. 3.2).