New technique for beam steering with fixed parabolic reflectors

A technique is described which offers the potential of achieving wide-angle beam steering with fixed parabolic reflectors. The technique involves a primary-feed device with an aperture field distribution which can be adapted to match the distorted field distributions resulting from a parabolic reflector when an off-axis plane wave is incident. To provide an adaptation without deterioration of the system signal/noise ratio, which requires only a movement of the primary feed along a given locus and an adjustment of noninteracting phase shifters, the primary feed carries out a spatial Fourier transformation of the intercepted fields. The technique has been implemented in an experimental X band antenna and beam steering of ±15 beamwidths achieved with negligible distortion of the directional pattern and less than 0.5 dB loss in gain.