Photonic-Assisted True Time Delay Beamforming With Spatial Anti-Interference Capability

Abstract

A photonic-assisted true time delay (TTD) beamforming system capable of simultaneous beam and null steering (NS) is proposed and experimentally demonstrated. The system integrates a directly modulated laser with an optical delay attenuation module to achieve TTD and NS weighting. This approach enables spatial filtering without compromising the broadband beamforming performance achieved by optical TTD. The phase adjustment for the null weighting is precalculated and converted into optical delay, while the amplitude adjustment is achieved through optical attenuation. In a proof-of-concept experiment, 5° step beam steering was achieved with an eight-element array. The system suppressed frequency-sweeping interference with a NS depth of 30 dB and over 1 GHz suppression bandwidth at 10 GHz. The null region enhancement (NRE) technique improves the robustness of the system in spatial anti-interference capabilities. The spatialfrequency response shows stable main beam gain across varying frequencies while null regions are formed. The proposed scheme addresses the issue of interference from sidelobe leakage in TTD beamforming and shows promise in meeting the spatial anti-interference requirements of future wideband radar and wireless communication systems.