In a mobile integrated service digital broadcasting-terrestrial (ISDB-T) system, the usage of a 3-elements electrical steerable parasitic array radiator (ESPAR) antenna can be a solution to gain diversity while keeping low power consumption and compact hardware size. But, the ESPAR antenna also increases the channel estimation difficulty as the received signal from each element will interfere each others. Orthogonal matching pursuit (OMP) can become an alternative in obtaining channel information for the system with ESPAR antenna. However, the OMP technique has a drawback in huge matrix inner product in its computation. In this paper, we propose a 3-column OMP with measurement matrix strength reduction technique to reduce the complexity in the inner product computation. The propose method overall result can achieve more than 90% complexity reduction.