The conventional, and widely-used, approach to elevation beam spoiling is to apply quadrature phase weighting vertically across the AESA elements. While this does, indeed, spread the beam, the resulting radiation pattern has excessive amplitude variations (more than 3 dB) and very large sidelobes. To improve this performance, we adapt a method presented over 20 years ago by Kinsey to calculate phase weights that steer power from each radiating element towards a desired direction. By using a set of desired directions that define a uniform range of angles, a broadened beam is produced. Since the method steers power element by element, it has the side benefit of correctly accounting for variations in element power due to amplitude weights or taper. We therefore choose to add a small amplitude taper to reduce amplitude variations across the broadened beam, and to suppress sidelobes outside of the main beam.
The addition of a modest 22 dB Taylor taper, spread by non-quadratic phase weights that are calculated with Kinsey’s method, produces a 20 degree main beam with just ±0.5 dB maximum amplitude ripple. The first one-way sidelobe is nearly 25 dB down, with additional sidelobe suppression provided by the receive beams. The presentation will include details of the design approach applied to the squared-off elliptical AESA found in the notional APAR Requirements document, with plots of the resulting beam performance.