Distribution of 3 GHz effective radius (in kpc) as a function of redshift and colour-coded by M_⋆ (stars). Size measurements are taken from median stacked 3 GHz images of non-detections. Upper limits are given for unresolved stacks and correspond to the angular 3 GHz beam size (0.75″, grey dashed line). We observe a clear increase of R_e with galaxy M_⋆. The bins at M_⋆ > 10^10.5 M_⊙ with resolved emission are fitted with a power-law redshift trend, which yields R_e ∝ (1 + z)^{−0.18 ± 0.07} (orange solid line). A comparison study by Jiménez-Andrade et al. (2019) is shown (blue solid line) for 3 GHz detected SFGs at similar M_⋆ in COSMOS, obtaining R_e ∝ (1 + z)^{−0.26 ± 0.08}.