Active echo cancellation is an efficient method for reducing the target detected probability. The radar cross section (RCS) of the target detected by radar after using the active echo cancellation method is defined as the active radar cross section (ARCS). The ARCS concept, which may be used to evaluate reflection of the target under the effect of multiple antennas, is employed to design and achieve echo cancellation. In this paper, numerical simulation for active echo cancellation using antennas is designed. The direction of the radiation source is obtained by means of dual antenna angle measurement. Active echo cancellation is implemented by adjusting the radiation power and phase of the echo cancellation antenna. By using the proposed dual antenna structure, ARCS in the direction of the object facing the radiation source and its vicinity is significantly reduced. In addition, the effect of antenna position on reflection cancellation is discussed. From these simulation results, we conclude that the proposed method is efficient in reducing the target scattering intensity. Such investigation can be extensively applied into designing active echo cancellation strategies.