Variation of BEL amplitudes (A_BEL) with different continuum amplitudes (A_conti) and orbital eccentricities (e) of BBHs with M_•• = 10⁹ M_⊙ at ω = 0°. The two left columns show A_BEL as a function of A_conti (left panel) and e (middle-left panel) for the case when only the secondary BH is active (q_L = 1 : 0), and the two right columns show A_BEL vs. A_conti (middle-right panel) and A_BEL vs. e (right panel) for the case when both the BHs are active with q_L = 1 : 1. In each panel, the points connected by lines of the same color show results of a fixed mass ratio, and the four different mass ratios q_M = 0.1, 0.3, 0.5, and 0.7 are colored in blue, green, violet, and red, respectively. Each group of four points with different q_M but the same e are linked by gray lines.