The next generation Navy radar systems will require shared active phased array antennas (PAA). PAAs offer may advantages including steering without physical movement, accurate beam pointing, increased scan flexibility in two dimensions, precise PAA element phase and amplitude control to obtain low sidelobes, and reduced power consumption and weight. The complexity associated with controlling the many thousand array elements, while handling the broad bandwidth required of a shared antenna, makes the marriage of photonics and microwave radar attractive - especially when true-time-delay (TTD) is required for wide bandwidth and large scan angle steering. Our analysis has shown, however, that despite the attractiveness of utilizing photonics, the excessive complexity and cost and in some cases performance limitations of current photonic beamformer approaches will limit their acceptance in deployed systems. The novel TTD photonic beamformer proposed here offers a high performance but lower complexity and cost photonic TTD system using a novel combination of commercially available wavelength division multiplexing (WDM) components which we call WDM Delay Broadcasting TTD. In this approach fixed delays are encoded with wavelength and broadcast to all of the antenna subarrays. Our approach uses a simple tunable optical filter at the antenna element to decode the delay.
Keywords: Phased Array Antenna Photonic Radar True-Time-Delay Fiber Optic Acousto-Optic Aotf
