The impulse response of AMO is described by a saddle in the output midpoint domain. The shape of the saddle depends on the offset vector of the input data and on the output offset vector ,where the unit vectors and point respectively in the in-line direction and the cross-line direction. The analytical expression of the AMO saddle, as given in Appendix A, is,
The surface represented by equation amo_surf.eq is a skewed saddle; its shape is controlled by the values of the absolute offsets h1 and h2, and by the azimuth rotation . The spatial extent of the operator has a maximum for rotation of 90 degrees and vanishes when offsets and azimuth rotation tend to zero. Figure impulse-big shows the surface of the AMO impulse response when t1 is equal to 1 s, h1 is equal to 2 km, h2 is equal to 1.8 km, is equal to zero degrees, and is equal to 30 degrees.