The usual enhancement devices are constructed to give a maximum monostatic echo area. This is achieved by setting up a uniform phase distribution in the effective aperture of the device independent of the angle of incidence. Bistatic echo-area enhancement may be achieved by altering this phase distribution. Gable phase distribution is considered for the rectangular aperture and is applied to the case of the triple-bounce corner reflector. Both linear radial and quadratic radial phase distributions are treated for circular apertures and applied to the Luneberg reflector and those spherical devices described by Kay.It is shown that the echo pattern may be approximated as an exponentially decaying function of the bistatic angle θ, i.e. ε−γθ. In each case the parameter γ is related to some physical parameter of the device by a design process. The validity of this design process has been verified for a triangular triple-bounce corner reflector and a Luneberg reflector.