Disclosed is a shaped horn in conjunction with a dielectric tube for enhanced aperture directivity that can achieve a near optimum efficiency. The shaped horn provides additional mode control to provide an improved off-axis cross-polarization response. The horn shape can be individually optimized for isolated horns or for horns in a feed array. The feed array environment can produce results that lead to a different optimized shape than the isolated horn. Lower off axis cross-polarization can result in improved efficiency and susceptibility to interference.