aperture the source aperture has a first port for receiving a planar wavefront signal and a second port for providing a substantially cylindrical wavefront signal the parabolic reflector is positioned within the horn to receive the cylindrical wavefront signal transforming it to a substantially planar wavefront signal at a predefined location the output aperture is positioned at the predefined location and outputs the substantially planar wavefront signal corrugations are adjacently placed at both sides of the output aperture to optimize the antenna beam pattern application_number US 8149598 A description fig3 a illustrates one embodiment of the present invention consisting of a parabolic rectangular horn antenna the parabolic antenna 300 includes a source aperture 320 a parabolic reflector 340 and an output plate 360 having an output aperture 362 during signal transmission a signal is feed into the source aperture 320 located at a focal point 345 of the parabolic reflector 340 the source aperture 320 perturbs the phase of the signal transforming the signal 39 s planar wavefront into substantially a cylindrical wavefront as the signal propagates into the horn as the signal 39 s cylindrical wavefront reaches the parabolic reflector 340 the parabolic shape of the reflector 340 transforms the signal 39 s cylindrical wavefront into a substantially planar wavefront when the signal arrives at the output aperture 362 the wavefront of the signal is returned to a substantially planar wavefront the parabolic shape of the reflector 340 returns the source or received signal to its substantially planar wavefront without requiring a long horn length a large.