Croseye systems are designed to deflect missiles equipped with radar target seekers by reemitting the radar signal from two antennas in opposite phase and with nearly equal amplitude. The combined signal will produce a false target appaently located outside the antenna system that can deflect missiles from ships and aircraft using onboard antennas. Practical tests have demonstrated the validity of the crosseye concept, but it is also necessary to determine thelimits of operation under variable external conditions. In this report the basic requirements of crosseye jamming are summarized in terms of a geometrical model that allows one to study the effect of disturbances without going into unnecessary details. This is important because the success of crosseye jamming depends strongly on the required deflection. The process can be affected by scattering from the terrain, since the method is sensitive to phase shifts. It can be shown that in a reciprocal system scattering afects all signals in the same manner so that phase errors cancel. In a non-reciprocal system scattering far away from the propagation path may affect the performance. This effect is of particular interest to modern crosseye systems which are often designed to use a single receiver. In this case the radar signal is stored in a digital memory and retransmitted by two or more antennas. However, as shown in this report this method can make the system sensitive to scattering since phase cancellation is no more assured.