In this paper, the design of a compact tri-band (TB) branch line coupler (BLC) using a modified double-Lorentz (DL) composite right/left handed (CRLH) transmission line (TL) is described. By properly choosing the parameters of the DL CRLH TLs, the unit structure yields phase responses of -π/4, π/4 and -π/4 at three arbitrary operating frequencies. Employing this structure, a TB microstrip BLC operating at 0.195 GHz, 0.67 GHz and 1.465 GHz is achieved. The size of the proposed TB BLC is significantly compact, at 14.2% of the previous TB BLC when they are both designed using DL CRLH TLs for the same TB frequencies.As a result, the proposed TB BLC has a more compact size than that of the previous work by adopting new TB phase relationships. Simulated and measured results show good agreement, and the operating frequencies in all 3 bands are well attained. This proposed TB BLC is significantly compact, and has steady performances due to the reliable realization, which is very useful in practical applications.