An aperture phase compensation technique for off-axis beam synthesis in parabolic reflector antennas

An aperture phase compensation technique is described which utilizes an orthogonal beam-forming matrix to apply discrete phase correction to the unwanted aperture phase error terms. The technique utilizes the existence of the two-dimensional Fourier transform relationship between the electric field distribution in the aperture and that in the focal plane region. The phase error components present in the aperture of the antenna when the primary feed is displaced from the focus are identified, and a set of discrete corrections is applied to the aperture phase. The technique is investigated for both singly and doubly curved parabolic reflector antennas using linear and planar arrays coupled to one-dimensional and two-dimensional orthogonal beam-forming matrices respectively. The application of the technique is here confined to offset configurations.