Synthetic aperture focusing based on planar waves also known as coherent plane wave compounding (CPWC) was introduced to reduce the diffraction spreading effect of ultrasound at depths (Song et al. US Patent 6736780, 2004). CPWC has been widely used in shear wave elasticity imaging due to its capability of ultrafast frame rate (Montaldo, et al. IEEE TUFFC, vol. 56, 2009). However, CPWC based on unfocused (plane waves) or defocused Tx beams has an inherent limitation in imaging wider field of view (FOV) due to the use of sampling angle in transmitting steered ultrasound wave. The sampling angle causes an unwanted side-lobe artifact if the sampling interval of angle is not small enough to cancel the artifact.