Demonstration of a wide-band fiber-optic nulling system for array antennas

A novel technique for forming and steering squint-free wide-band nulls in the far-field pattern of an ultrawide-band array antenna is presented. The nulling system relies upon a fiber-optic dispersive prism tapped delay-line microwave filter to generate the appropriate nulling waveform. The null-forming architecture was integrated with a wide-band fiberoptic dispersive prism true-time-delay transmit beamformer for demonstration in an anechoic chamber. Measurements show null depths on the order of 15 dB over the 4-18-GHz bandwidth of the system for various steering angles, The demonstrated architecture may be used for simultaneous wide-band beamforming, sidelobe reduction, and jammer suppression.