Total intensity surface brightness as a function of the beam size (3″–100″) for the mock radio halos R1a (top), R2 (middle), and R6 (bottom). For each radio halo, the surface brightness is calculated within a circle of 3r_e in radius. The solid thin green line shows the average brightness, while the shaded region shows the maximum and minimum brightness fluctuations. The simulated surface brightness is compared with the sensitivity of wide band instruments (SKA Phase-1, SKA Phase-2, JVLA) to explore their potential in detecting the total intensity emission of halos at different radio power. The sensitivity refers to the 3-σ limit.